JP4082308B2 - Data recording / reproducing apparatus, data recording / reproducing method, program, and recording medium - Google Patents

Description

  The present invention relates to a data recording / reproducing apparatus, a data recording / reproducing method, a computer program, and a recording medium for a randomly accessible recording medium, and more particularly, to scan a magnetic head on a magnetic disk as a medium such as a hard disk. The present invention relates to a technique for a disk-type recording medium that performs data read / write operations. More specifically, the present invention relates to a technique for performing stable data recording / reproduction while shortening the access time to a desired data storage location.

JP 2000-276856 A JP 2000-278645 A

  With the development of information technology such as information processing and information communication, it has become necessary to reuse information created and edited in the past, and information storage technology has become increasingly important for this purpose. Up to now, information recording devices using various media such as magnetic tapes and magnetic disks have been developed and spread.

Among these, HDD (Hard Disk Drive) is a magnetic recording type auxiliary storage device. The HDD drive unit contains several magnetic media as recording media and is rotated at high speed by a motor. The medium is coated with a magnetic material such as iron oxide or cobalt / chromium by plating or forming a thin film.
Then, by scanning the magnetic head in the radial direction on the surface of the rotating medium, the magnetization corresponding to the data is generated on the medium, and writing or reading of the data can be performed.

  Hard disks are already widespread. For example, as a standard external storage device for a personal computer, for installing various software such as an operating system (OS) and applications necessary for starting the computer, and for saving created / edited files Hard disk is being used. Usually, the HDD is connected to the computer main body via a standard interface such as IDE (Integrated Drive Electronics) or SCSI (Small Computer System Interface), and its storage space is an operating system such as FAT (File Allocation Table). Managed by a file system that is a subsystem of

  Recently, the capacity of HDDs has been increasing. Along with this, not only as a conventional auxiliary storage device for computers but also as a hard disk recorder for storing broadcast-received AV content, the application field has expanded, and it has begun to be used for recording various content.

Here, taking the case of being used as an auxiliary storage device for a computer as an example, the physical formatting method of the hard disk and the data read / write operation to the hard disk will be considered.
A large number of “tracks” are formed concentrically on the hard disk as sections for recording data. Then, track numbers such as 0, 1,... Are assigned from the outermost periphery to the inner periphery. The greater the number of tracks on the disk surface, the greater the storage capacity of the media.

Further, each track is divided into “sectors” which are recording units. Normal data read / write operations on the disk are performed in units of sectors. Although the sector size differs for each medium, the hard disk sector is generally determined to be 512 bytes. Further, in consideration of the media usage efficiency, in order to make the recording density on each track substantially uniform, the number of sectors is increased toward the outer track having a longer circumference. This is called a “Zone Bit Recording” (zone bit recording) method.
When the zone bit recording method is adopted, the recording density on each track can be made almost uniform, but the data transfer speed for each track becomes non-uniform. The data transfer rate becomes lower as the disk moves in the inner circumferential direction.

  Also, in the case of an HDD configured by concentrically overlapping several media, it can be considered that the same numbered track of each media is arranged in a cylindrical shape, and this is called a “cylinder”. Each cylinder is assigned the same number as the track number, and cylinder 0, cylinder 1,. The plurality of heads inserted between the media always operate as one body and move between the cylinders.

  A CHS mode can be given as a method for designating (addressing) a target sector. This is a method of accessing desired data by designating PBA (Physical Block Address) on the disk in the order of C (Cylinder), H (Head), and S (Sector).

  On the other hand, in the CHS system, there is a limit to the CHS parameters that can be specified on the computer main body side that operates as a host for the HDD, and it becomes impossible to cope with an increase in capacity of the hard disk. For this reason, an LBA (Logical Block Address) mode is adopted. This expresses a cylinder number, a head number, and a sector number (CHS) by a logical serial number called LBA starting from 0.

  In the conventional HDD, in order to access the medium and read / write data, the magnetic head is first scanned on the medium in order to reach the track with the target sector. This is called a “seek” operation of the magnetic head. Next, in order to reach the target sector on the track, the medium rotates and waits until the target sector comes directly under the magnetic head. This is called “waiting for rotation”.

  As the capacity of the disk increases, the track density increases and the track width becomes extremely narrow. Therefore, in order to write and reproduce data accurately, positioning of the magnetic head requires high accuracy. Therefore, a servo technique is adopted in which the position of the magnetic head is always aligned with the center of the track. It is possible to check whether or not the magnetic head is at the center of the track by writing signals called “servo patterns” on each track at regular intervals and reading them with the magnetic head. The servo pattern is written with high accuracy in the manufacturing process of the HDD. For example, a signal for positioning the head, a cylinder number, a head number, and a servo number are written in the servo area.

Many conventional HDDs have an interface such as IDE or SCSI for connection to a computer. Then, the disk drive control from the computer main body has a basic operation of designating the LBA indicating the head sector and the number of sectors to be accessed using a command set defined by the interface.
In this case, on the HDD side, access can be made while creating from the designated head sector and creating a sequence for prefetching by predicting the sector to be accessed thereafter.

This pre-read operation is based on the premise that sectors having continuous addresses are allocated to a series of data. Normally, sectors having consecutive addresses exist in consecutive head numbers or track numbers.
When large data is continuously written on the medium, the prefetching operation at the time of reading works effectively.

  However, when fragmentation of the storage area progresses and large data is fragmented into small pieces and distributed in multiple locations, the read-ahead at the time of reading points to another data, so it works effectively. I can't. It can be said that such a phenomenon occurs because the HDD does not grasp the file structure handled by the host (computer main body or the like) side that requests data read / write.

  In addition, when the prediction is lost due to a new access request from the host side, the disk drive seeks to the track including the sector where the requested data exists, and when the tracking is completed, the target sector is not accessed. Wait for it to be possible. Here, seek time and rotation waiting time occur.

  Prefetched data is stored as long as the capacity of the data buffer allows. If the prediction is lost continuously or sporadically, the unused old data in the data buffer is discarded in order. Further, seek activation cannot be performed during this prefetching.

As described above, it can be said that seek time and rotation waiting time, time loss due to seek start delay due to invalid prefetching, and data loss due to invalid prefetching have occurred.
In a normal disk drive, in order to shorten the seek time and the rotation waiting time, the rotation speed of the disk is increased. This is because there is no regularity in the amount of data and the data structure handled on the host side such as a computer, and thus it is difficult to improve by the access method. However, the method of increasing the number of revolutions of the disk is disadvantageous in terms of power consumption and storage capacity, and causes a problem.

In many conventional external storage systems such as HDDs, error correction is performed in units of one sector (one sector is usually composed of 512 bytes). As a result, error correction can be performed for random errors occurring in each sector. Error correction cannot be performed for random errors or burst errors that exceed the correctable range. In view of this, the read error has been kept below a certain level by performing a retry operation.
However, such a retry operation needs to be read again after waiting for one rotation. This further causes a delay in data read time.
For example, in a system that handles AV content, there is a situation where high transfer speed is required, such as HD (high definition image quality) playback or special playback, and even if an uncorrectable read error occurs in a sector, time Sometimes it is not possible to retry. In such a case, at present, the process cannot be advanced without error correction, and as a result, the reproduction quality is deteriorated.

For example, the above-mentioned Patent Document 2 has information indicating the importance level of the data block to be recorded, and based on this information, retry is performed for the important data block, and no retry is performed otherwise. A technique for switching is disclosed.
Further, the above-mentioned Patent Document 1 has information indicating the importance of the data block to be recorded, and based on this information, the error correction capability is increased for the important data block, and other than the normal correction capability. A technique for performing such switching is disclosed.
These techniques function appropriately to some extent, particularly in systems that handle AV contents, but more effective techniques are required for avoiding retries and correcting errors.

Furthermore, if a disturbance such as vibration is applied during the reading of these AV contents, the occurrence of errors will be greater than when reading without a disturbance. For this reason, the number of data that cannot be corrected for errors increases, resulting in poor reproduction quality.
In particular, the occurrence of errors in a state where disturbance is applied tends to occur frequently immediately after seeking. For example, when a disturbance is applied, it takes a long time to become on-track, resulting in an error.
The error may be random or a burst. The greater the disturbance, the greater the number of sectors in which intra-sector correction for correcting random errors becomes impossible.

Another factor for the increase in the occurrence of errors during reading is aging. When reading data written in the past, it is conceivable that the SPM (spindle motor) or VCM (voice coil motor) deteriorates to show the same phenomenon.
The occurrence of an error immediately after seeking due to this disturbance naturally has an adverse effect on data quality, access time, and transfer speed, and countermeasures against such errors are also required.

The present invention has been made in view of the above-described problems, and realizes the following objects as a data recording / reproducing apparatus, a data recording / reproducing method, a computer program, and a recording medium.
That is, the access time to a desired data storage location is shortened.
In addition, stable data reproduction is performed without reducing the transfer rate.
In addition, it is possible to correct errors over a wider range of random errors and burst errors, avoiding retry operations and data quality degradation, reducing transfer speed degradation, and enabling stable data reproduction. Like that.
Further, the influence of an error immediately after seeking due to disturbance is avoided, so that a decrease in transfer speed is reduced and stable data reproduction can be performed.

The data recording / reproducing apparatus of the present invention is a data recording / reproducing apparatus for a disk recording medium in which concentric tracks are formed and each track is divided into a plurality of sectors. Then, seek means for seeking the target track, data access means for accessing on the seeked track, and an error correction code for error correction of the data are generated, and data is errored based on the error correction code. Error correction means for correcting. The error correction means sets a first error correction code unit for a predetermined data amount unit, sets a second error correction code unit for a plurality of first error correction code units, and sets a plurality of error correction code units. Forming an error correction block including the first error correction code unit and the second error correction code unit added thereto, and a sector by the second error correction code is formed by the seek unit. The error correction block is generated so that it becomes the first read sector by the data access means when moving to a certain track on the disk recording medium.
In order for the sector based on the second error correction code to be the first read sector, the error correction means arranges the second error correction code at the head of at least the error correction block. Thus, the error correction block is formed. Alternatively, the error correction block is formed so that the second error correction code is arranged at least at the beginning and end of the error correction block.
The error correction means forms the error correction block so as to complete the error correction block in units of one or a plurality of tracks.
The error correction means generates an error correction code by the Reed-Solomon code method.
Further, the error correction block formed by the error correction means has an interleave structure in the first or second error correction code unit.
Further, the disk recording medium is formed at each position so that the servo areas are radial on the disk recording medium.

Further, the data access means starts the write access from the head sector that can be accessed on the track sought by the seek means, and accesses one track.
In this case, at the time of write access, the data access means allocates relative position addresses in order from the sector that started the access on the track to each sector, and at the time of read access, the data read from each sector on the track is allocated. Relocate according to the relative position address to reproduce the written data.
The error correction means forms the error correction block so that two or more error correction blocks do not exist per track and complete the error correction block in units of one or more tracks.

The data recording / reproducing method of the present invention is a seek step for seeking a target track as a data recording / reproducing method for a disk recording medium in which concentric tracks are formed and each track is divided into a plurality of sectors. And a data access step for accessing the seek track, and an error correction step for generating an error correction code for error correction of the data and for error correction of the data based on the error correction code. In the error correction step, a first error correction code unit is set for a predetermined data amount unit, a second error correction code unit is set for a plurality of first error correction code units, and a plurality of error correction code units are set. Forming an error correction block composed of the first error correction code unit and the second error correction code unit added thereto, and a sector by the second error correction code is formed in the seek step. The error correction block is generated so that it becomes the first read sector in the data access step when moving to a certain track on the disk recording medium.
In the error correction step, the error correction block is formed so that the second error correction code is arranged at least at the head of the error correction block. Alternatively, the second error correction code is arranged at the beginning and end.
In the error correction step, the error correction block is completed in units of one or a plurality of tracks.
In the error correction step, an error correction code is generated by the Reed-Solomon code method.
The error correction block formed in the error correction step has an interleave structure in the first or second error correction code unit.

In the data access step, write access is started from the head sector that has become accessible on the track sought in the seek step, and one track is accessed.
In this case, in the data access step, at the time of write access, the relative position address is assigned to each sector in order from the sector that started the access on the track, and at the time of read access, the data read from each sector on the track is allocated. Relocate according to the relative position address to reproduce the written data.
In the error correction step, the error correction block is formed so that two or more error correction blocks do not exist per track and the error correction block is completed in units of one or more tracks.

  In the program of the present invention, concentric tracks are formed, and each track is described in a computer-readable format for executing a data recording / reproducing process on a disk recording medium divided into a plurality of sectors on a computer system. This is a program for executing the steps of the data recording / reproducing method.

  In the recording medium of the present invention, a first error correction code unit is set for a predetermined data amount unit, and second error correction code units for a plurality of first error correction code units are set. An error correction block including the first error correction code unit and the second error correction code unit added thereto is formed, and the error correction block includes the second error correction code. Is set so that it becomes the first read sector when moving to a certain track by a seek operation, and the data having the structure of the error correction block is recorded on each recording track. To do.

With the above-described present invention, the above-described intended object is realized.
That is, the random error in the sector can be corrected by using the first error correction code (C1) unit, and the intra-sector error correction range can be increased by using the second error correction code (C2) unit. It is possible to correct errors that exceed or burst errors that span sectors. In other words, by setting the error correction block configuration to C1 + C2, even when retrying cannot be performed to maintain the data transfer rate higher than desired, error correction is further performed at C2 when error correction becomes impossible at C1. Therefore, a more stable system can be provided. In this way, it is possible to perform error correction even for random errors and burst errors in a wider range, and by avoiding the retry operation, stable data reproduction can be performed without reducing the transfer speed. .
Further, in the error correction block configuration, the sector (C2 sector) based on the second error correction code is set to be the first read sector when it is moved to a certain track by the seek operation. Is started from the C2 sector. That is, the sector in which errors occur most frequently due to a disturbance or the like is the C2 sector, thereby minimizing the influence of the disturbance on the data sector.
In addition, an error in the C2 sector can effectively reduce data loss due to an error even when an error occurs exceeding the set ECC correction capability. That is, even if the C2 sector is lost due to the error correction being impossible, the data sector is not damaged, and therefore it can be expected that the data sector is normal even if the error correction becomes impossible.

Further, the data access means starts a write access from the head sector that has become accessible on the track sought by the seek means, and performs an access for one track. For example, an access for one track is performed from a sector in which the magnetic head is on-track. This eliminates the waiting for rotation during writing. Also, at the time of read access, by setting one track as an access unit, the indefinite process of pre-reading can be omitted and the seek activation timing can be determined reliably.
In particular, in this case, the data access means allocates relative position addresses in order from the sector that started access on the track to each sector at the time of write access, and data read from each sector on the track at the time of read access. Can be accessed from any sector of the track by reproducing the written data by rearranging according to the relative position address.
Then, the waiting for rotation can be minimized by reading and writing from an arbitrary head position immediately after seeking. As a result, the number of seeks is minimized, and the access time is shortened. Particularly in this case as well, if an arbitrary head position immediately after seeking corresponds to the C2 sector, the influence of disturbance during read access can be minimized.
In the case of such an access method, a write / read request source (for example, a host device such as a computer connected to the HDD) does not need to be aware of the sector address on the disk. Further, by using a relative position address that requires a short data size, the storage area can be effectively used.
Also, at the time of read access, the data read from each sector on the track is rearranged according to the relative position address on the buffer memory, for example, so that the original data can be assembled regardless of the position of the sector where the access is started. However, in this case, it is appropriate to form the error correction block so that there are no two or more error correction blocks per track and to complete the error correction block in units of one or more tracks.

According to the present invention, it is possible to provide an excellent data recording / reproducing apparatus, data recording / reproducing method, program, and recording medium capable of performing efficient and stable data reproduction with redundancy by error correction codes. it can.
That is, the random error in the sector can be corrected by using the first error correction code unit, and the error exceeding the intra-sector error correction range can be corrected by using the second error correction code unit. It is possible to correct burst errors that span in between. As a result, even in a situation where a retry cannot be performed in order to keep the data transfer rate higher than desired, an error can be corrected appropriately and a more stable system can be provided. In this way, it is possible to perform error correction even for random errors and burst errors in a wider range, and by avoiding the retry operation, stable data reproduction can be performed without reducing the transfer speed. .
Further, in the error correction block configuration, the sector (C2 sector) based on the second error correction code is set to be the first read sector when it is moved to a certain track by the seek operation. Is started from the C2 sector. That is, the sector in which errors occur most frequently due to disturbance or the like is the C2 sector, so that the influence of the disturbance on the data sector can be minimized and stable data reproduction can be performed.

Furthermore, according to the present invention, one track can be set as an access unit by starting the access from the first sector which becomes accessible on the seek track and performing the write access for one track. Data write access control that does not cause a wait can be realized. That is, the data access time can be shortened.
Also in such an access method, if the head position immediately after seeking corresponds to the C2 sector, the influence of disturbance can be minimized. That is, stable reading can be performed at the time of reading access.

Hereinafter, embodiments of the present invention will be described in the following order with reference to the drawings.
1. 1. Configuration of hard disk device 2. Servo area 3. Access operation ECC configuration5. 5. ECC block setting in which the sector immediately after seek is the C2 sector Application examples

1. Hard disk unit configuration

FIG. 1 schematically shows an overall configuration of an HDD (Hard Disk Device) 10 according to an embodiment of the present invention.
As shown in the figure, the HDD 10 includes a CPU (Central Processing Unit) 11, a ROM (Read Only Memory) / RAM (Random Access Memory) 12, a disk controller 13, a buffer RAM 14, a data read / write control unit 15, and the like. , A servo controller 16 and a magnetic disk 21.

The magnetic disk 21 is composed of one or a plurality of sheets, and the recording surface is single-sided or double-sided (front and back of the disk). A head is disposed on the recording surface. FIG. 1 shows a state in which two magnetic disks 21a and 21b are arranged and two recording / reproducing heads (magnetic heads) 22a and 22b are provided correspondingly.
In other words, several magnetic disks (platters) can be concentrically overlapped in the drive unit. At that time, the same track number of each magnetic disk is arranged in a cylindrical shape (cylinder), and the same cylinder as the track number. It is specified by number.
As shown in FIG. 1, one recording / reproducing head 22 is arranged for one magnetic disk 21 when one side of the magnetic disk 21 is a recording surface.
When both surfaces are recording surfaces, two recording / reproducing heads 22 are arranged for one magnetic disk 21.

In FIG. 1, the CPU 11 executes control codes stored in the ROM / RAM 12 to comprehensively control the operation in the HDD 10.
The disk controller 13 receives a command from a host (not shown) connected via the interface 17. The CPU 11 performs this command processing, and the disk controller 13 instructs a hardware operation to the data read / write control unit 15 and the servo control unit 16 according to the command processing result.
Write data received from the host via the interface 17 and data read from the magnetic disk 21 and passed to the host are temporarily stored in the buffer RAM 14.

  The data read / write control unit 15 performs a code modulation process to create a data pattern to be actually recorded, and writes data to the magnetic disk 21 via the preamplifier 25. Conversely, the read data is taken in from the magnetic disk 21 via the preamplifier 25 and the data is demodulated.

  The servo control unit 16 synchronously drives a voice coil motor (VCM) 23 that moves an arm on which the magnetic head 22 is mounted and a spindle motor (SPM) 24 that rotates the magnetic disk 21, so that the magnetic head 22 becomes a magnetic disk. 21 is controlled to reach a predetermined range on the target track. Furthermore, control is performed to seek the head position to a predetermined position from the servo pattern on the disk.

A large number of tracks, which are sections for recording data, are formed concentrically on the magnetic disk 21. For example, the track numbers are 0, 1, 2,... From the outermost periphery of the disk 21 toward the inner periphery. Allocated. Each track is further divided into sectors, and this sector unit is the minimum unit in which data read / write operations can be performed.
The amount of data in the sector is fixed at 512 bytes, for example.
In addition to data, header information, error correction code, and the like are added to the actually recorded sector.

  As for the number of sectors per circuit, a ZBR (Zone Bit Recording) system is adopted in which the number of sectors increases as it goes to the outer track where the peripheral length becomes longer. That is, the number of sectors per track over the entire circumference of the magnetic disk 21 is not uniform, and the magnetic disk 21 is divided into a plurality of zones in the radial direction, and is set to have the same number of sectors in each zone.

FIG. 3 shows an example of the ZBR method.
In the example shown in the figure, the disk is divided into three zones, and zones 0, 1, 2 and zone numbers are given in order from the outermost periphery. Further, each zone includes a plurality of tracks.
In FIG. 3, each zone is divided by sectors. In this case (as a schematic example only), zone 0 is composed of 64 sectors, zone 1 is composed of 32 sectors, and zone 2 is composed of 16 sectors. ing. When switching zones, the number of sectors, the spindle motor 24 rotation speed is kept constant, the recording / reproducing clock is made variable, etc., the linear recording density is kept within a predetermined range, and the storage capacity per disk is increased. To be determined.

  FIG. 2 shows the internal configuration of the disk controller 13 of FIG. 1 in more detail. As shown in the figure, the disk controller 13 includes a CPU interface 31, a host controller 32, a buffer controller 33, a servo controller 34, a disk formatter 35, and an ECC controller 36. In the figure, an arrow that causes data movement is indicated by a double line.

The CPU interface 31 is an interface between the CPU 11 and the RAM / ROM 12, and notifies a command from the host or receives a command processing result from the CPU 11.
The host controller 32 communicates with a host connected via the interface 17.
The buffer controller 33 controls the exchange of data between the buffer RAM 14 and each unit in the disk controller 13.
The servo controller 34 reads the servo information from the servo pattern on the magnetic disk 21 by controlling the operations of the VCM (voice coil motor) 23 and the SPM (spindle motor) 24, and passes this information to the servo controller 15.
The disk formatter 35 performs control for writing data on the buffer RAM 14 to the magnetic disk 21 or reading data from the magnetic disk 21.
The ECC controller 36 generates and adds an ECC code from the data stored in the buffer RAM 14 at the time of writing, or performs error correction at the time of reading.
Such a disk controller 13 shown in FIG. 3 receives formatter control information and ECC control information from the CPU 11.

  By the way, as an access method of this example, an access may be performed based on a so-called LBA (Logical Block Address), or, as will be described later, an access using a relative address in units of tracks may be performed.

In the case of accessing by LBA, the formatter control information is format information for accessing the sector specified by LBA after being accessible on the sought track. This information is sent to the disk formatter 35 via the CPU interface 31, where a data formatter is generated.
The ECC control information is information for setting the ECC block configuration having the first error correction code C1 and the second error correction code C2, and for example, according to the number of sectors for each zone. When the ECC block configuration is changed, this is information for instructing the configuration. This information is sent to the ECC controller 36 via the CPU interface 31, where the ECC block configuration is set, and the buffer RAM 14 is accessed to perform predetermined ECC processing.

When accessing using a relative address in units of tracks, the formatter control information starts accessing from the first sector after it becomes accessible on the seek track, and accesses for one track. The format information is sent to the disk formatter 35 via the CPU interface 31, where a data formatter is generated.
The ECC control information is information for setting an ECC block configuration that is completed in units of tracks. For example, when the ECC block configuration is varied according to the number of sectors for each zone, the configuration is indicated. It becomes information to do. This information is sent to the ECC controller 36 via the CPU interface 31, where the ECC block configuration is set, and the buffer RAM 14 is accessed to perform predetermined ECC processing.

  The control information (formatter control information, ECC switching control information) is stored in the ROM / RAM attached to the CPU 11 in FIG. Sometimes, data may be read from the magnetic disk 21 and stored in the buffer RAM 14. In this case, control information may be sent from the buffer RAM 14 to each unit.

The HDD 10 according to the present embodiment is configured as described above. In this configuration, as described below, data access control that does not cause rotation waiting is performed, and access time is shortened and data transfer speed is reduced. Realize a fast system. In addition, by making it possible to correct errors over a wide range of random errors and burst errors, a retry operation can be avoided, a decrease in transfer speed can be reduced, and stable data reproduction can be performed. Furthermore, in the track to be accessed, the sector immediately after seeking becomes the sector of the second error correction code (C2), thereby reducing adverse effects due to disturbances and the like.

2. Servo area

FIG. 4 shows an example of the arrangement of servo areas on the magnetic disk 21.
In FIG. 4, the solid line in the radial direction indicates the servo area SRV (not the sector separation as shown in FIG. 3).
In the example shown in FIG. 4, servo areas are radially arranged on the magnetic disk 21 as indicated by 32 solid lines in the radial direction. That is, the servo area SRV is formed regardless of the zones 0, 1, and 2 that are concentric circles. That is, in any zone, 32 servo areas SRV are formed per track. Note that the 32 servo areas SRV per track is merely an example for explanation.

When one sector is given by 512 bytes, the size per sector (sector size) is small compared to the capacity between the two servo areas on the track, so that a certain servo area on the track, A plurality of sectors are arranged between the next servo areas.
The arrangement of these sectors is mainly determined for each ZBR zone. That is, when the zone is switched, the number of sectors arranged between the servo areas also differs.
When switching the zones, for the specific number of sectors, the rotational speed of the spindle motor 24 is kept constant, the recording / reproducing clock is made variable, and the linear recording density is kept within a predetermined range, so that the memory per disk is stored. Determined to increase capacity.

In the example of FIG. 4, the number of servo areas per track is 32. For example, if the number of servo areas is 96, the servo areas are arranged radially with respect to the disk. A plurality of sectors are arranged between the next servo areas.
The servo bandwidth is determined by the number of servo areas per track, the number of rotations of the disk, the servo frequency, etc., and is set according to the system requirements.

In the servo area SRV, for example, track positioning control is performed. That is, when the track trace by the magnetic head 22 passes through the servo area SRV, information on whether the track is turned on or off is obtained.
Here, it is assumed that the track position is shifted due to the addition of a disturbance such as vibration during data reading. When the track moves largely, the entire servo control is performed from the beginning. That is, the data reading is interrupted, and a necessary track is accessed again to read the data.

3. Access behavior

As described above, as an access method, an access method based on LBA and an access method using relative addresses in units of tracks are conceivable. Since the access method based on the LBA is an access method that is usually adopted in many HDDs, an access method using relative addresses in units of tracks will be described here, although detailed description is avoided.

In the case of this access method, the HDD (hard disk device) 10 accesses one track from the sector on which the magnetic head 22 is on-track. Sector numbers on the same track are not fixed and can be given by relative positions.
As a result, access can be started from any sector on one track. That is, by using one track as an access unit, it is possible to reliably determine the timing of seek activation without the need to perform processing consisting of an uncertain element such as prefetching. In addition, it is not necessary to wait for rotation by accessing from any sector of one track. As a result, the number of seeks can be minimized and the access time can be shortened.

When writing to a predetermined track, a relative position starting from the sector where access is started is given to the sector.
Further, when reading is performed, reading is performed from the sector where access is started, and the data is developed on the buffer RAM 14 based on the relative position sector number. Therefore, reading may be started from any sector.

An example of the sector format used in the track of the magnetic disk 21 to enable such an operation is schematically shown in FIG.
As shown in FIG. 5A, the sector is composed of relative position data representing the relative position of the sector on the track, a data body, and an ECC for performing error correction on the entire sector area. These are the error correction range and recording range.
By including the relative position data as a header in the error correction range, for example, even if a random error occurs in a sector, the relative position data can be recovered by error correction, thereby realizing a smooth disk access operation. be able to.
In general, a sector has an ID field for recording the address of the sector. However, since a relative position is recorded instead of an absolute position, the size of the ID field can be reduced. Accordingly, the field size that can be used for the data body in the sector increases, and the storage area is effectively used.

  When writing to a track, the sector is given a relative position starting from the sector from which access was started, ECC data is generated based on the relative position and the original recording data, and the relative position field, data field, and Record in the ECC field. Since writing is started from the sector where access is started, there is no need to wait for rotation.

  Further, when reading is performed, reading is performed from the sector where access is started on the track, and the storage position on the buffer RAM 14 is determined based on the sector position obtained by the relative position field. Therefore, even if data reading is started from an arbitrary sector, the data stored on the track is restored in the original order by rearranging the data on the buffer RAM 14 based on the relative position. Also, since reading is started from the sector where access is started, there is no need to wait for rotation.

FIG. 5B schematically shows another example of the sector format used in the track of the magnetic disk 21 in the HDD 10 according to the present embodiment.
Also in this case, as described above, the sector is composed of relative position data representing the relative position of the sector on the track, a data body, and ECC for performing error correction on the entire sector area. However, the entire error correction range is used, but unlike the example shown in FIG. 5A, the relative position field is not included in the recording range. Therefore, as the relative position field disappears, the field size usable for the data body in the sector becomes larger than in the above-described example, and the storage area is effectively used.

In this case, when writing to the track, a relative position starting from the sector where access was started is given to the sector, ECC data is generated based on the relative position and the original recording data, and only the recording data and ECC data are recorded on the sector. To record. Since writing is started from the sector where access is started, there is no need to wait for rotation.
Further, when reading is performed, reading is performed from the sector where access is started, and error correction is performed using ECC, thereby regenerating a relative position that has not been written in the sector. Based on this relative position, the storage position on the buffer RAM 14 is determined. Therefore, even if data reading is started from an arbitrary sector, the data stored on the track is restored in the buffer RAM 14 in the original order. Also, since reading is started from the sector where access is started, there is no need to wait for rotation.

An example of communication with the host at the time of data recording / reproducing according to the above sector format will be described.
An example of communication when the HDD 10 of this example performs data writing by a command from a host connected via the interface 17 is as follows.
First, the host issues a data write command to the HDD 10. In response to this, the HDD 10 responds with an address area having the minimum seek time from the current access sequence.
When the host receives a response from the HDD 10, the host transfers the data content of the designated address area size (number of bytes, number of sectors, etc.). The HDD 10 writes the received data content in units of tracks.

Here, as described above, when relative position information is allocated to each sector based on the access start position on the track at the time of writing, when a write request is made, on the host side, specific information such as the cylinder number, head number, sector number, etc. There is no need to be particularly aware of the writing location, and there is no need to indicate these.
Further, the address area notified from the HDD 10 side to the host may be a simple one such as a content number for identifying content requested to be written by the host.
On the HDD 10 side, a conversion table of each content number and a physical recording location on the disk 21 is prepared.
Since disk access is performed in units of tracks, the conversion table with content numbers is as shown in FIG. 6, for example. That is, track numbers and head numbers are registered corresponding to the content numbers.

  Note that the sector number of the CHS method is not included in the conversion table. As described above, in the configuration in which the relative position information is allocated to each sector based on the access head sector on the track at the time of writing, the data is based on the relative position information of each sector regardless of the access head sector on the track at the time of reading. Relocation is possible. For this reason, it is not necessary to specify the access start sector in the conversion table.

  This conversion table is written in the buffer RAM 14. Writing of the conversion table is performed by software executed by the disk controller 13 or the CPU 11 when write data is received from the host.

A communication example when the HDD 10 of this example reads data by a command from a host connected via the interface 17 is as follows.
The host issues a data read command to the HDD 10. The target content number is specified in the read command.
On the other hand, the HDD 10 specifies the target track from the conversion table of FIG. 6 based on the content number, and performs the seek operation of the magnetic head 22. Then, the data on the disk 21 is transferred in accordance with the sequence of the address area responded at the time of data writing.
At the time of this data read request, the host side only specifies a desired content number, and does not need to be aware of a specific write location (PBA) such as a cylinder number, a head number, or a sector number.

  As described above, the HDD 10 accesses one track from the sector in which the magnetic head 22 is on-track. By using one track as an access unit, it is possible to reliably determine the timing of seek activation without the indefinite process of prefetching. In addition, since access can be performed from any sector of the track, read / write is performed from an arbitrary head position immediately after seek, thereby eliminating the waiting for rotation. As a result, the number of seeks is minimized, and the access time is shortened.

Such a disk access operation is realized by the disk controller 13 instructing a hardware operation to the data read / write control unit 15 and the servo control unit 16 according to the command processing result by the CPU 11.

4). ECC configuration

As described above, when the HDD 10 accesses in units of one track, it is appropriate that an ECC block with one track as a basic unit is formed on the magnetic disk 21.
When an access method based on LBA is adopted, an ECC block having one track as a basic unit is not necessarily formed, but of course, one track may be used as a basic unit.
Here, an example of an ECC block based on one track will be described.

FIG. 7 shows an example of the ECC configuration with one track as a basic unit.
In the example of FIG. 7A, the magnetic disk 21 is divided into zones, and an example of the ECC block configuration in the zone n is shown. That is, as in a predetermined track TK indicated by a broken line in the zone n, one round of each track is set as a structural unit of the ECC block.
The ECC block includes C1 that performs intra-sector correction and C2 that performs inter-sector correction.
An error correction unit (ECC block constituent unit) composed of C1 + C2 has one track as a basic unit, and no two or more ECC block constituent units exist in each track.

FIG. 7B shows another example of the ECC block. Also in this case, the magnetic disk 21 is divided into zones, and an example of an ECC block is shown in the zone m. In this example, three tracks in the zone m become ECC block constituent units. This example uses an integral multiple of one track as a structural unit, and is not limited to three tracks of course.
Also in such an example, the ECC block includes C1 that performs intra-sector correction and C2 that performs inter-sector correction. An error correction unit (ECC block constituent unit) composed of C1 + C2 has one track as a basic unit, and no two or more ECC block constituent units exist in each track.

FIG. 8 shows an example of the ECC block structure of the magnetic disk 21 adopting the ECC block configuration shown in FIG.
Here, it is assumed that a Reed-Solomon code having a symbol length of 8 is used as the ECC correction code.
The effective number of sectors for one track in a certain zone of a certain magnetic disk is assumed to be 768 sectors. For example, one sector includes 4 bytes of CRC (cross check code) and a total of 48 bytes of C1 to 512 bytes of data, and is composed of 4 interleaves.

In the example of the ECC block configuration in FIG. 8, 704 sectors from sectors 0 to 703 are given as data areas, and 64 sectors from sectors 704 to 767 are given as C2 areas. C2 is composed of, for example, 4 interleaves of 16 sectors each.
With such a configuration, one ECC block has a total of 768 sectors, which is one round in this zone, and a track unit can be realized.

Consider the error correction capability in this example.
By using C1 for a random error, it is possible to correct up to 24 bytes per sector (up to 48 bytes if byte loss information is obtained).
Furthermore, for burst errors, error correction can be performed up to 32 sectors per track (up to 64 sectors using the CRC result) by using C2.

In addition, the description can be made in the same way even when a predetermined number of sectors, not in units of tracks, is an ECC block.
In this case, for example, the ECC block may be a small ECC block unit such as 192 (= 176 sector data + 16 sector C2) sectors.

Here, the circumstances of adopting the error correction block as described above will be described.
In many conventional HDD systems, error correction is performed only in units of one sector including 512-byte data and information bits.
Therefore, error correction can be performed for random errors occurring in each sector, but for random errors that exceed the correctable range, or burst errors, that is, errors that continue long beyond the sector, Error correction could not be performed.

In such a case, for example, by performing a retry operation, it is possible to make the read error below a certain level and perform error correction. However, the retry operation basically corresponds to an increase in the extra access time for one turn per time.
Here, even if the access time is shortened by the above-described track unit access, if a retry operation occurs, the access time eventually increases, resulting in a delay in data read time.
For example, when handling AV content such as HD (high-definition image quality) playback or special playback, when a high transfer speed is required, even if an uncorrectable read error occurs, there is no time to perform a retry operation in time. There is. In such a case, at present, the processing is proceeding without correcting the reading error. As a result, the reproduction quality is deteriorated.

Therefore, the ECC configuration is configured as described above to realize stable data reproduction and reduce the number of cases where error correction that causes a retry occurrence cannot be performed.
That is, in addition to the conventional C1 correction, which is an error correction in units of one sector, a C2 correction capable of correcting between sectors is added. The error correction unit (ECC block) composed of C1 + C2 is completed by, for example, a track.

  When an ECC block unit composed of C1 + C2 is completed in one round of a track, one track can be used as an access unit, and data access control without causing rotation waiting can be realized. That is, the access time to a desired data storage location can be shortened. Also, if there are no more than two ECC blocks on the same track, data access control that does not cause rotation waiting can be performed even when the ECC configuration is a unit of a plurality of tracks. Can be realized.

By the way, in the Reed-Solomon code having a symbol length of 8 shown in FIG. 8, interleaving can be applied to 512-byte data.
9 and 10 show examples in which interleaving is applied to the ECC block configuration of this example.
In FIGS. 9 and 10, interleaving is applied to sector n. One sector is divided into 4 parts by a 4-byte header, 512-byte data, and 4-byte CRC. A 12-byte ECC code C1 is added to each unit.
For example, interleave 0 is configured by adding a 12-byte parity to a 1-byte header, 128-byte data, and a 1-byte CRC. The same applies to the interleaves 2, 3, and 4.

Then, the arrangement in the sector is interleave 0 for the first, interleave 1 for the first, interleave 2 for the second, interleave 3 for the third, interleave 0 again for the fourth, and so on. Arrange in order.
A 4-byte header, 512-byte data, and then a 4-byte CRC are added, and subsequently created C1 codes are arranged in the same order.
FIG. 9 shows an interleaved decomposition, and FIG. 10 shows an arrangement when addresses 0 to 567 are allocated on the memory.

In this way, FIGS. 9 and 10 are in the same sector unit as in FIG. That is, a 4-byte header and 512-byte data are added with a 4-byte CRC and an ECC code C1 of 48 bytes in total to form one sector, which is configured as a main part of a recording sector on the magnetic disk 21.
Note that the actual recording data configuration further includes a preamble, a synchronization signal, a postamble, and the like. In addition, as another configuration example of the sector unit, there are a format that does not have a header file, a format that does not have a CRC, and the like.

  Such an interleaving configuration may be determined mainly by a hardware configuration. In a Reed-Solomon code having a symbol length of 8, the interleaving configuration is applied in the C1 direction (that is, the sector direction) as shown in FIG.

  Note that the above-described interleaving may be applied to C2 in which ECC is executed between sectors. Even in this case, the same configuration and operation can be realized by replacing the Byte of the DATA portion with the sector in FIG. 9 and expanding the Byte in the C2 direction (that is, the direction orthogonal to the sector).

In this example, one sector is 512 bytes of data, but the sector size is not limited to this. For example, even when 1024 bytes or 2048 bytes are used as one sector, the sector is the same as above. An ECC block configured between every sector and between sectors can be realized.

By the way, when the ECC block is completed in units of tracks, when the zone of the magnetic disk 21 is switched, the number of sectors per track is different. Therefore, in the configuration with the same ECC parity number, the error correction capability is large for each zone. It can be different.
In this case, by making the ECC block configuration variable for each zone, the redundancy of the error correction code can be kept within a certain range. As a result, the error correction capability has the same strength and the same over the entire circumference of the disk. can do.
For example, in the example of FIG. 3, the number of sectors per track is 64 sectors in zone 0, 32 sectors in zone 1, and 16 sectors in zone 2. The rotation speed is the same for each zone, but the operation clock is changed, and the linear recording density in each zone is within a certain range.

At this time, ECC is added with C1 for each sector. The configuration of C1 is fixed and the same. Specifically, for example, the configuration shown in FIG.
As for the configuration of C2, in zone 0, 8 out of 64 sectors are given as C2 parity, in zone 1 4 out of 32 sectors, and in zone 2 2 out of 16 sectors are C2 parity. Give as.
When configured in this way, the ratio of the number of C2 parity sectors to the number of data sectors for one round in each zone becomes constant, and the C2 correction capability can be made the same in each zone.
In an actual format, there are few cases where the value is just divisible, such as the relationship between the zone and the number of sectors. Therefore, it is only necessary to set the redundancy of the ECC portion to be within a certain range.

In this way, the ECC block is completed in units of tracks, has a C1 + C2 configuration, and further has an interleaved configuration. In addition, the ECC configuration is variable for each zone, and the redundancy of the ECC portion is controlled within a predetermined range. Error correction can be performed over a wider range of random errors and burst errors over the entire circumference of the disk, thereby realizing stable data reproduction.
In this example, the C1 portion of the ECC configuration is fixed and the C2 portion is variable to control the redundancy of the ECC portion, that is, the error correction capability, within a predetermined range. However, for example, the C1 portion may be variable for each zone and the C2 portion may be fixed to control the error correction capability within a predetermined range, or the error correction capability may be controlled comprehensively by controlling C1 and C2. You may make it control inside.

5. ECC block setting with sector immediately after seek as C2 sector

The ECC block structure is basically as described above. However, in this embodiment, as a sector arrangement on the track, the sector that starts access immediately after seeking the track is the C2 sector. ECC block configuration is set.
With respect to such an ECC block configuration, a case where the LBA access method is adopted and a case where the above-described access method using a relative address in units of tracks is described, respectively.

First, the case of the LBA access method will be described with reference to FIGS.
FIG. 11 shows the details of the sector arrangement in this example. In this case, the access unit is not limited to the track unit, and an LBA is allocated to each sector.
FIG. 11 schematically shows the sector arrangement of two tracks in the zone 1 in the middle circumference of the disk 21 having zones 0, 1, and 2 as shown in FIG. As described above, each track in zone 1 has 32 sectors.
As shown in the figure, certain two tracks (TK1, TK2) included in the zone 1 are assigned in order from “1” to “64” as LBA numbers. These “1” to “64” are numerical values for explanation, and these are actually values as LBA. LBA is a value that is continuously assigned to each sector from the outer circumference side to the inner circumference side, for example, over the entire track circumference on the disk.
In a certain track TK1 in zone 1, LBA numbers “1” to “32” are allocated to each sector. In the next track TK2, LBA numbers “33” to “64” are assigned to the sectors. In this case, the first sector “1” of the track TK1 and the first sector “33” of the track TK2 The position is shifted by the track skew determined by information such as the area.
For example, the track skew is given in units of servo frames when a plurality of servo areas arranged radially on the disk are used as a frame between the servo areas. In this way, the first sector is shifted from one track to another in consideration of the time required for track jumping and disk rotation as shown by an arrow TJ, for example, as a seek to the next track.
In other words, the access to the track TK1 is performed from the sectors “1” to “32”, and subsequently moves to the track TK2. However, as described above, the head sector is arranged with a shift by the track skew as described above. Access from sector “33” can be made with less waiting time.

The access at the time of reading according to the LBA follows from LBA “1” to “32” of the track TK1 in FIG. 11 and from LBA “33” to “64” after seeking to the track TK2.
In this example, one track has an ECC block configuration, and of the 32 sectors in one cycle of zone 1, the data sector is composed of 28 sectors and the C2 sector is composed of 4 sectors.
At this time, in FIG. 11, LBA “1” to “4” are arranged as C2 sectors in the track TK1, and further LBA “33” to “36” are arranged as C2 sectors in the next track TK2.

This corresponds to recording / reproducing by placing the C2 sector at the head of the ECC block in the ECC block configuration as shown in FIG. This is shown in FIG.
FIG. 12 shows, for example, sectors constituting an ECC block for one track (or n tracks), for example, 32 sectors for one track in zone 1 of FIG.
In this example, the LBA number from the first sector starts with “3FC”.
In this case, the first four sectors “3FC” to “3FF” are set as the C2 sector. Assuming that the LBA “1” of the track TK1 in FIG. 11 is actually “3FC”, an ECC block is formed such that the C2 sector is arranged in the first four sectors as shown in FIG. 12, and data is stored in the track TK1. By performing the writing, “1” to “4” become the C2 sector as shown in FIG.
Also in the next track TK2, an ECC block having the first four sectors as C2 sectors is formed as shown in FIG. 12, and data writing is performed, so that “33” to “36” are changed to C2 as shown in FIG. It becomes a sector.
That is, by writing data in such an ECC block according to the LBA, at the time of data reading, in each track, the ECC block of the ECC block is placed at the head position where reading starts immediately after on-track. C2 sectors can be provided.

When performing continuous reading at a high speed in reading with seeking, it may be difficult to perform recovery by retry processing even if a reading error occurs in order to maintain a predetermined transfer speed. Further, the occurrence of a read error becomes more prominent when a disturbance such as vibration is applied. The occurrence of the error occurs frequently in the vicinity of seeking and reading immediately after on-track. As this cause, for example, the positioning of the track is not sufficiently stable.
Here, when reading immediately after seeking is extremely unstable, or reading immediately after seeking under a situation where disturbance has been applied, many errors occur, resulting in a sector error more than expected, and C2 of the set ECC block Consider the case where the correction ability is exceeded.
When error correction cannot be performed, the read data is output as it is without performing processing such as error correction. On the other hand, the sector part where many errors have occurred is a sector near the start of reading.
Under such circumstances, if the C2 sector, which is a redundant sector, is arranged in the sector portion immediately after the start of reading as in this example, even if an uncorrectable error occurs, data loss due to the error is prevented. Can be reduced.

That is, when moving to a certain track by a seek operation, an error correction block is generated and written so that the first read sector of the track becomes the C2 sector, so that at the time of read access, The sector can be a C2 sector which is a redundant part.
More specifically, by forming an error correction block in which the C2 sector is arranged at least at the head of the error correction block, at the time of read access, read access is started from the C2 sector immediately after on-track.
At this time, if an error has occurred due to a disturbance or the like, many sectors having an error occur in the C2 sector portion.
Eventually, it is possible to output data with less influence on a sector including an error output without being recovered. This is because most error sectors are generated in redundant sectors. Therefore, more stable data reproduction is realized.

By the way, in the examples of FIGS. 11 and 12, a predetermined number of C2 sectors (for example, 4 out of 36 sectors) for obtaining a predetermined redundancy according to the number of sectors in the ECC block are placed at the head of the ECC block. Although they are arranged together, at least the first sector can be set as the C2 sector, so that the above-mentioned desired effect can be obtained.
For example, in FIG. 13, C2 sectors, which are four of the 36 sectors, are allocated to LBA “1” “2” “3” “32” in the track TK1, and LBA “33” “34” in the track TK2. ”,“ 35 ”and“ 64 ”. That is, this is an example in which the top 3 sectors and the end 1 sector of the ECC block are C2 sectors.
Even when the ECC block configuration is set and data is written as described above, the C2 sector having the ECC block configuration is arranged at the head position where reading is started immediately after on-track when data is read thereafter. Therefore, the same effect as described above can be obtained.
Of course, if at least the first sector (the first one to several sectors) is the C2 sector, this does not prevent the remaining C2 sector from being placed in an intermediate sector other than the head or the end.
Further, even when the actual read position immediately after the on-track is before or after the assumed LBA, the same effect can be obtained if the C2 sector is arranged at the start position where reading is started.

  Although FIG. 11 shows an example in which the ECC block configuration is a unit of one track, it is not limited to this. That is, even when the number of sectors other than the track unit is used in the ECC block configuration, similarly, when moving to a certain track by seeking, the first read sector of the track becomes the C2 sector. By doing so, more stable data reproduction is realized.

Next, the case where the above-described access method using relative addresses in units of tracks will be described with reference to FIGS.
FIG. 14 shows the details of the sector arrangement. In this case, the access unit is a track unit, and a relative address is assigned to each sector as described above.
FIG. 14 schematically shows the sector arrangement of two tracks in zone 1 as in the case of FIG. Each track in zone 1 has 32 sectors.
As shown in the figure, relative addresses “1” to “32” are allocated to certain two tracks (TK1, TK2) included in the zone 1, respectively. The relative addresses “1” to “32” are sequentially allocated at the time of write access to each track, and are not fixed to the physical sector positions on the track.
For example, the sector of the relative address “1” of the track TK1 is a sector that can first be accessed for writing after seeking the track TK.

  If writing is continuously performed on the tracks TK1 and TK2, relative addresses “1” to “32” are allocated to the sectors in the track TK1 in the zone 1, and each sector is also allocated to the next track TK2. Relative addresses “1” to “32” are allocated. In this case, the displacement of the position of the first sector “1” of the track TK1 and the first sector “1” of the track TK2 is a seek operation from the track TK1 to the TK2 ( This is a deviation from immediately after the track jump TJ) until the access is started. This does not necessarily coincide with the track skew determined by the information such as the rotational speed and the servo area described above.

The access at the time of writing according to the relative address follows from the relative address “1” to “32” of the track TK1 in FIG. 14, and after the seek to the track TK2, the relative address “1” to “32” of the track TK2. To go.
In this example, one track has an ECC block configuration, and of the 32 sectors in one cycle of zone 1, the data sector is composed of 28 sectors and the C2 sector is composed of 4 sectors.
At this time, in FIG. 14, relative addresses “1” to “4” are arranged as C2 sectors in the track TK1, and relative addresses “1” to “4” are arranged as C2 sectors in the next track TK2. .

This corresponds to recording / reproducing by placing the C2 sector at the head of the ECC block in the ECC block configuration as shown in FIG. This is shown in FIG.
FIG. 15 shows, for example, sectors constituting an ECC block for one track, and shows, for example, 32 sectors as tracks in zone 1 of FIG.
Then, as shown in the figure, the ECC block is formed so that the top four sectors with relative addresses “1” to “4” are arranged as C2 sectors. When such an ECC block configuration is performed and data is sequentially written to the tracks TK1 and TK2, for example, as shown in FIG. 14, the sectors with relative addresses “1” to “4” at the head of each track are C2 sectors. It becomes.
That is, when moving to a certain track by a seek operation, an error correction block is generated and written so that the first read sector of the track becomes the C2 sector, so that at the time of read access, The sector can be a C2 sector which is a redundant part.
More specifically, by forming the error correction block so that the C2 sector is arranged at least at the beginning of the error correction block, at the time of read access, the read access can be started from the C2 sector immediately after the on-track. it can.
As a result, it is possible to output data with less influence on a sector including an error output without being recovered. Therefore, realizing more stable data reproduction is the same as the example described with reference to FIGS.

By the way, in the case of the access method based on the relative address, even if the sector of the relative address “1” to “4” of each track is the C2 sector as shown in FIG. It is not necessarily limited to be.
Therefore, the ECC block configuration for each track is made as described above, and when data is written to a plurality of tracks by one continuous write access, during the read operation for the plurality of tracks, For each track after the second track (in this case, track TK2), it is necessary to control the operation so that the sector that is the head position where reading starts immediately after the on-track becomes the C2 sector. This point will be described.

As described above, in the case of access based on a relative address, writing / reading may be performed from any sector in one track. For writing, a relative address is allocated from a writable sector, so it can be started from any sector. At the time of reading, the read sector data for one track can be rearranged on the buffer RAM 14 according to the relative address. So you can start reading from any sector.
That is, since it can be accessed from any sector of the track, it has been described above that waiting for rotation can be eliminated by reading and writing from an arbitrary head position immediately after seeking.
This indicates that it is not always necessary to read from the sector having the relative address “1” at the time of reading.

Considering the case where the seek is first performed on the track TK1 in FIG. 14, it is only necessary to perform read access for one round from the sector regardless of the relative address of the sector which can be read after the on-track. . For example, if the head position immediately after the seek is the sector position of the relative address “15”, the relative addresses “15” “16”... “32” “1” “2”. It only has to be accessed. This eliminates the waiting for rotation.
However, for the next track TK2, it is sufficient to seek immediately after the sector "14" is read. In this case, the track TK2 is on-tracked before and after the sector "14". End up. That is, the first sector immediately after the on-track is not the C2 sector (sectors “1” to “4”). Then, the effect with respect to the above-described disturbance cannot be obtained.

Therefore, the first track waits for rotation if necessary, and <1> read access starts from the sector of relative address “1”, or <2> read access for one track. After that, when the relative address “32” is reached, seek to the next track is performed.
When the read access is started from the sector of the relative address “1” as in <1> above, for example, after seeking to the track TK1 and on-tracking, the rotation waits as much as necessary, and the relative address Reading is started when the sector of “1” is reached. Then, if the next track TK2 is sought when reading is performed for one track from the relative addresses “1” to “32”, the reading is started from the vicinity of the sector of the relative address “1” in the track TK2. . Therefore, the first sector immediately after seeking can be the C2 sector.
Further, although not shown in FIG. 14, when each track is read continuously with the tracks TK3, TK4,..., The first sector immediately after the seek can be the C2 sector.
In this case, the tracks TK3, TK4,... Are tracks on which write access has been performed by a series of continuous operations from the track TK1. In the case of the access method based on the relative address, writing may be executed from any sector immediately after seeking. However, as long as the track has been written by continuous write access, as in the tracks TK1 and TK2. The positions of the first sector “1” are shifted by the amount corresponding to the seek operation (track jump TJ). That is, if a seek operation is performed immediately after sector “32”, the next track can be read from the vicinity of sector “1”.

  In addition, when the relative address “32” is reached after the read access for one track in the above <2> is performed, for example, seek to the track TK1 and on-track Immediately after reading, one track is read without waiting for rotation. Then, after reading one track, it waits for rotation as much as necessary, and seeks to the next track TK2 when the relative address “32” is reached. In this case, in the track TK2, reading is started from the vicinity of the sector of the relative address “1”. Therefore, the first sector immediately after seeking can be the C2 sector. Since the relative addresses “1” to “32” are read from the track TK2 and seek to the next track TK3, the same applies to the track TK3.

As described above, when the access method using the relative address is adopted, read access from an arbitrary sector immediately after seeking is possible, but in this example, only the first track has the relative address “1”. Or read after one track and wait until the relative address “32” for seeking. As a result, each track after the subsequent track TK2 is read from the C2 sector immediately after seeking.
Here, the first track is the first track when a predetermined number of plural tracks are taken as one unit. For example, a predetermined number of tracks that are continuous during recording and reproduction and that have a constant track skew due to seeking are set as one unit.
By doing so, the advantage of the access method based on the relative address that eliminates the waiting for rotation at the time of reading is partly limited, but the fact that waiting for rotation is unnecessary in the write access remains unchanged. For example, when writing to the tracks TK1 and TK2 is considered, it is necessary to wait for rotation in the LBA access method when the track TK1 is on-track. In the access method using the relative address, the track TK1 is required. Writing can be started with an arbitrary sector immediately after being on-tracked as a relative address “1”.

In the example of FIGS. 14 and 15, a predetermined number of C2 sectors (for example, 4 out of 36 sectors) for obtaining a predetermined redundancy according to the number of sectors in the ECC block are used at the head of the ECC block. In this case, the expected effect described above can be obtained by setting at least the first sector as the C2 sector.
That is, for example, relative addresses “1”, “2”, “3”, and “32” may be used as the C2 sector in each track. Even when the ECC block configuration is set and data is written as described above, the C2 sector having the ECC block configuration is arranged at the head position where reading is started immediately after on-track when data is read thereafter. Therefore, the same effect as described above can be obtained.
Of course, if at least the first sector (the first one to several sectors) is the C2 sector, this does not prevent the remaining C2 sector from being placed in an intermediate sector other than the head or the end.
Further, even when the actual read position immediately after the on-track is around the assumed position, the same effect can be obtained if the C2 sector is arranged at the head position where reading is started.

  Although FIG. 14 shows an example in which the ECC block configuration is a track one-round unit, the invention is not limited to this, and the ECC block configuration may be a track n-round unit. In this case, however, the C2 sector is arranged at the head of each unit in a unit divided into sectors for one track (for example, every 32 sectors in the example of FIG. 14). That is, in the ECC block configuration, each leading sector for each number of sectors for one track is a C2 sector as shown in FIG.

  As described above, the HDD 10 according to the present embodiment forms and arranges an ECC block so that the first read sector immediately after seeking for a track, that is, a sector in which an error due to a disturbance is likely to occur is the C2 sector. Data loss can be reduced with respect to the occurrence of an error that cannot be corrected by C2, which occurs in a situation where recovery cannot be performed by a retry operation or the like, and as a result, more stable data reproduction can be performed.

This point will be described together with processing at the time of reading.
FIG. 16 shows the flow of error sector correction processing at the time of reading.
First, in step F101, data reading processing is performed. As a result, the number of sectors in a predetermined unit is read and stored in the buffer RAM 14. In the case of access using a relative address, it is necessary to perform the control <1> or <2> for the first track of the reading process.
Next, in step F102, the disk controller 13 fetches sector data in units of ECC blocks from the buffer RAM 14, and checks whether a sector error has occurred in the fetched sector. This can be determined, for example, by performing C1 correction given in one sector.
If no sector error has occurred, the C1-corrected data is returned to the buffer RAM 14. In step F106, the redundant sector portion, that is, the C2 sector is removed from the sector of the ECC block unit in the buffer RAM 14, and only the necessary data sector is extracted, thereby completing the data reading process. That is, sector data from which the C2 sector is removed in the buffer RAM 14 is output from the interface 17 via the host controller 32. In this case, the output read data is correct data with no error.

On the other hand, when the occurrence of a sector error is detected in step F102, the C2 correction process is subsequently performed in step F103.
If sector correction by C2 is possible, the process proceeds from step F104 to F105, and the read data fetched from the buffer RAM 14 is subjected to correction processing by C2 to obtain correctly corrected data. The corrected data is written into the buffer RAM 14.
Then, in step F106, the redundant sector portion, that is, the C2 sector is removed from the corrected ECC block unit data, and only the necessary data sector is extracted and output, thereby completing the data reading process. Also in this case, the output read data is correct data with no error.

However, when C2 correction is impossible in step F104, sector error correction processing is not performed. In this case, the disk controller 13 sends the data fetched from the buffer RAM 14 for error correction back to the buffer RAM 14 as it is. In step F106, the redundant sector C2 sector is removed from the uncorrected ECC block unit data, and only the necessary data sector is extracted and output, completing the data reading process. In this case, the output read data may contain an error.
However, as can be understood from the description in FIGS. 11 to 15, the sector in which an error has occurred is likely to be the C2 sector. Therefore, even if the error cannot be corrected, there is a high possibility that the error sector is deleted when the C2 sector is deleted and output in step F106. Therefore, as a whole, even if a C2 uncorrectable error occurs, data loss due to an uncorrectable error can be reduced.

6). Application examples

The present invention is not limited to the above-described example, and can be applied to various cases as follows.
Although the number of the magnetic disks 21 in the HDD 10 is two, the present invention can be applied to the case of one HDD or three or more HDDs 10. Further, the present invention can also be applied to the case where the front and back surfaces of one disk 21 are recording surfaces. Further, various configurations of the number of magnetic heads 22 are conceivable, but this does not hinder the application of the present invention.
In general, in the HDD, the disk 21 is fixedly incorporated in the apparatus, but an HDD in which the disk 21 is removable is also conceivable. The present invention can be applied to such an apparatus.
Furthermore, the present invention can also be applied to disk systems other than HDDs (optical disk recording / reproducing apparatus, magneto-optical disk recording / reproducing apparatus).

In addition, regarding the arrangement of the C2 sector, it is not always necessary to arrange the first sector of C2 in the first read sector immediately after the on-track after seeking, and the first read sector immediately after the on-track is included. By disposing the C2 sector in the periphery, the present invention can be similarly applied.
In the ECC block configuration in FIGS. 12 and 15, C2 is arranged at the head portion. However, this is not necessarily limited. Finally, after the seek, the C2 sector is located in the head read sector immediately after on-tracking. It only has to be arranged.

The program of the present invention is a program for realizing the functions of the HDD 10 described above. In particular, a process for realizing the ECC block configuration described with reference to FIGS. 11 to 15 is executed by being started up by the CPU 11 and controlling each part of the HDD 10 based on the program.
This program can be stored in advance in the ROM / RAM 12, for example. Alternatively, a form in which the data is stored in the magnetic disk 21 and loaded into the ROM / RAM 12 is also conceivable.

It is a block diagram of the whole structure of HDD of embodiment of this invention. It is a block diagram of a disk controller of the HDD of the embodiment. It is explanatory drawing which showed typically the disc format structure of embodiment. It is explanatory drawing of the servo area of the disk of embodiment. It is explanatory drawing of the error correction range of embodiment. It is explanatory drawing of the conversion table for the access of embodiment. It is explanatory drawing of the ECC block used as the track unit of embodiment. It is explanatory drawing of the ECC block structure of embodiment. It is explanatory drawing of the interleave structure of embodiment. It is explanatory drawing of the interleave structure of embodiment. It is explanatory drawing of the example of C2 sector arrangement | positioning in the LBA access system of embodiment. It is explanatory drawing of the ECC block structural example of embodiment. It is explanatory drawing of the example of other C2 sector arrangement | positioning of embodiment. It is explanatory drawing of the example of C2 sector arrangement | positioning in the relative address access system of embodiment. It is explanatory drawing of the ECC block structural example of embodiment. It is a flowchart of the process at the time of reproduction | regeneration of embodiment.

Explanation of symbols

  10 HDD (Hard Disk Device), 11 CPU, 12 ROM / RAM, 13 Disk Controller, 14 Buffer RAM, 15 Data Read / Write Control Unit, 16 Servo Control Unit, 21, 21a, 21b Magnetic Disk 22, 22a, 22b Magnetic Head

Claims (29)

A concentric track is formed, and each track is a data recording / reproducing apparatus for a disk recording medium divided into a plurality of sectors,
Seek means to seek the target track;
Data access means for accessing on the sought track;
An error correcting means for generating an error correcting code for error correcting the data and correcting the error of the data based on the error correcting code;
The error correction means sets a first error correction code unit for a predetermined data amount unit, sets a second error correction code unit for a plurality of first error correction code units, and sets a plurality of error correction code units. Forming an error correction block including the first error correction code unit and the second error correction code unit added thereto, and a sector by the second error correction code is formed by the seek unit. A data recording / reproducing apparatus for generating the error correction block so as to become a first read sector by the data access means when moving to a certain track on the disk recording medium.   2. The data recording / reproducing apparatus according to claim 1, wherein the error correction unit forms the error correction block so that the second error correction code is arranged at least at the head of the error correction block. .   2. The data recording according to claim 1, wherein the error correction means forms the error correction block so that the second error correction code is arranged at least at the beginning and end of the error correction block. Playback device.   2. The data recording / reproducing apparatus according to claim 1, wherein the error correction unit forms the error correction block so that the error correction block is completed in units of one or a plurality of tracks.   2. The data recording / reproducing apparatus according to claim 1, wherein the error correction means generates an error correction code by a Reed-Solomon code method.   2. The data recording / reproducing apparatus according to claim 1, wherein the error correction block formed by the error correction means has an interleave structure in the first or second error correction code unit. 2. The data recording / reproducing apparatus according to claim 1, wherein the disk recording medium is formed at each position so that servo areas are radial on the disk recording medium.
  2. The data access unit according to claim 1, wherein the data access unit starts a write access from the head sector that has become accessible on the track sought by the seek unit, and performs an access for one track. Data recording / reproducing device.   The data access means allocates relative position addresses to each sector in order from the sector that started the access on the track at the time of write access, and reads the data read from each sector on the track at the time of read access. The data recording / reproducing apparatus according to claim 8, wherein the written data is reproduced by rearranging according to the above.   The error correction means is characterized in that the error correction block is formed so that two or more error correction blocks do not exist per track and the error correction block is completed in units of one or more tracks. The data recording / reproducing apparatus according to claim 8. As a data recording / reproducing method for a disk recording medium in which concentric tracks are formed and each track is divided into a plurality of sectors,
Seek step to seek the desired track;
A data access step for accessing on the sought track;
An error correction step for generating an error correction code for error correction of the data and correcting the error of the data based on the error correction code; and
In the error correction step, a first error correction code unit is set for a predetermined data amount unit, a second error correction code unit is set for a plurality of first error correction code units, and a plurality of error correction code units are set. Forming an error correction block composed of the first error correction code unit and the second error correction code unit added thereto, and a sector by the second error correction code is formed in the seek step. A data recording / reproducing method, characterized in that the error correction block is generated so as to become the first read sector in the data access step when moving to a certain track on the disk recording medium.   12. The data recording / reproducing method according to claim 11, wherein in the error correction step, the error correction block is formed so that the second error correction code is arranged at least at the head of the error correction block. .   12. The data recording according to claim 11, wherein in the error correction step, the error correction block is formed so that the second error correction code is arranged at least at the beginning and end of the error correction block. Playback method.   12. The data recording / reproducing method according to claim 11, wherein in the error correction step, the error correction block is formed so that the error correction block is completed in units of one or a plurality of tracks.   12. The data recording / reproducing method according to claim 11, wherein in the error correction step, an error correction code is generated by a Reed-Solomon code method.   12. The data recording / reproducing method according to claim 11, wherein the error correction block formed in the error correction step has an interleave structure in the first or second error correction code unit.   12. The data access step according to claim 11, wherein write access is started from the head sector that has become accessible on the track sought by the seek step, and one track is accessed. Data recording and playback method.   In the above data access step, at the time of write access, the relative position address is assigned to each sector in order from the sector that started the access on the track, and at the time of read access, the data read from each sector on the track is assigned to the relative position address. The data recording / reproducing method according to claim 17, wherein the written data is reproduced by rearranging according to the above.   In the error correction step, the error correction block is formed so that there are no two or more error correction blocks per track and the error correction block is completed in units of one or more tracks. The data recording / reproducing method according to claim 17. Concentric tracks are formed, and each track is a program described in a computer-readable format for executing data recording / reproduction processing on a disk recording medium divided into a plurality of sectors on a computer system.
Seek step to seek the desired track;
A data access step for accessing on the sought track;
An error correction step for generating an error correction code for error correction of the data and correcting the error of the data based on the error correction code; and
In the error correction step, a first error correction code unit is set for a predetermined data amount unit, a second error correction code unit is set for a plurality of first error correction code units, and a plurality of error correction code units are set. Forming an error correction block composed of the first error correction code unit and the second error correction code unit added thereto, and a sector by the second error correction code is formed in the seek step. A program for generating the error correction block so that it becomes the first read sector in the data access step when moving to a certain track on the disk recording medium.   21. The program according to claim 20, wherein in the error correction step, the error correction block is formed so that the second error correction code is arranged at least at the head of the error correction block.   21. The program according to claim 20, wherein in the error correction step, the error correction block is formed so that the second error correction code is arranged at least at the beginning and end of the error correction block.   The program according to claim 20, wherein in the error correction step, the error correction block is formed so that the error correction block is completed in units of one or a plurality of tracks.   21. The program according to claim 20, wherein in the error correction step, an error correction code is generated by a Reed-Solomon code method.   21. The program according to claim 20, wherein the error correction block formed in the error correction step has an interleave structure in the first or second error correction code unit.   21. The program according to claim 20, wherein in the data access step, write access is started from the head sector that has become accessible on the track sought by the seek step, and access for one track is performed.   In the above data access step, at the time of write access, the relative position address is assigned to each sector in order from the sector that started the access on the track, and at the time of read access, the data read from each sector on the track is assigned to the relative position address. 27. The program according to claim 26, wherein the program is rearranged to reproduce the written data.   In the error correction step, the error correction block is formed so that two or more error correction blocks do not exist per track and the error correction block is completed in units of one or a plurality of tracks. Item 26. The program according to item 26. A first error correction code unit is set for a predetermined data amount unit, a second error correction code unit for a plurality of first error correction code units is set, and a plurality of the first error correction code units are set. An error correction block including a correction code unit and the second error correction code unit added thereto is formed,
The error correction block is set so that the sector by the second error correction code becomes the first read sector when it moves to a certain track by a seek operation,
A recording medium in which data having the configuration of the error correction block is recorded on each recording track.

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