JP3326694B2 - Data access method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data access method suitably applied to, for example, an external storage device of a computer.

[0002]

2. Description of the Related Art In a data recording device such as a hard disk device, a floppy disk device, or a magneto-optical disk device, the minimum unit of data access is a data block called a sector. These data storage devices are used as an external storage device of a computer. Conventionally, a data block size per sector (hereinafter referred to as a sector size), which is a unit of the access, is used.
The mainstream was 512 bytes.

However, in recent years, with the background of increasing the capacity of data files and improving the reliability of data, it has been called for to increase the sector size.
There are media that handle data in units of bytes or about 2.5 Kbytes. Therefore, 512 bytes,
There is a strong demand for compatibility between these large-capacity sector sizes, and various proposals have been made.

[0004]

These proposals basically consist of stacking a plurality of small sectors having a small data size (for example, 512 bytes) to form a large sector having a larger size (for example, 2.5 Kbytes). The data in the small sector unit is recorded and reproduced continuously. For this reason, the protection against burst errors has been inevitably reduced for data in small sector units.

In view of the above points, the inventor of the present application has
We have proposed a new data recording method that can ensure data reliability even for data with a small sector size.
The data recording method proposed earlier, for example,
If such a servo scheme optical disk drive, utilizes the fact that it is recorded and reproduced by the smaller data size than the sector size.

Namely, the sample servo scheme optical disk (including a magneto-optical disk), as shown in FIG. 4, the staggered mark including pits 21 and 22 a pair of distributed to the left and right from the track center 20 recorded service Boeria as, along with being preformatted at predetermined intervals, data area Ad and time, are spatially separated. It referred to the area of the unit including the servo area As and the data area Ad segment, the sample servo
For square type can record and reproduce data in the segment unit.

In the invention proposed above, the user sector size is recorded and reproduced on the disk 2 in such a manner that the small sector of 512 bytes / 1 sector and the large sector of 2560 bytes / 1 sector are compatible. In hitting
For example, as shown in the recording pattern on the disk 1 in FIG.
The data is recorded and reproduced so as to form a data recording area Db for a plurality of large sectors. In this case, when writing data for one small sector to the disk 1, the data for one small sector is written. Divide into units of one segment,
The data of the divided one segment unit is recorded in discrete segments, for example, in every five segments.

An example of the invention proposed above will be described in more detail. In this case, the data formats of the small sector and the large sector are as shown in FIGS.
FIG. 6 shows the data format of a small sector in this example. That is, the data of the small sector is a total of 52 bytes of user data of 512 bytes and control data of 8 bytes.
As shown in FIG. 6, the 0-byte data is horizontal × vertical = 10
The data is arranged in 4 (bytes) × 5 (rows), and an error correction code is generated for the 520 bytes of data, and
It is formed by adding a parity of 0 bytes (16 bytes × 5 rows). The read / write direction of the data on the memory is the vertical direction, but one segment (4 bytes × 5 lines =
The data is read from the memory every 20 bytes) and recorded on the disk as described later, and the reproduced data from the disk is written into the memory every segment.

In this example, as the error correcting code, for example, (120, 104, 17) Reed-Solomon codes are generated for each row of 104 bytes of data to generate 16 bytes of parity. Is done. Therefore, the data of one sector is 600 bytes in total. 1
An error in a small sector can be corrected using the parity within the range of its error correction capability.

The large sector data has a structure in which five small sectors are stacked in the column direction as shown in FIG. That is, for the 104 bytes of data in each row, the (120, 104, 17) Reed-Solomon code is generated to generate a 16-byte parity, for example, with respect to 104 bytes of data in each row in the horizontal direction. The vertical direction is 5 rows × 5 = 25 rows. In this case, the read / write direction of the data on the memory is the vertical direction in FIG.
The data is sequentially read out from the memory in the vertical direction and sequentially recorded on the disk, and the data in the segment unit reproduced from the disk is sequentially written in the memory in the vertical direction. , Large sectors as shown in FIG. At this time, the recording pattern of the large sector is, as described later, data recorded for each small sector, and is recorded every five segments in one-segment units. It is compatible with.

FIG. 8 shows a track format in the case of this example. In the case of this example, as shown in FIG. 8D, one segment includes a 4-byte servo area, a 1-byte reference area for reproducing clock synchronization, and a 20-byte user data area. As shown in FIG. 8A, one track has data (= large data) for 30 small sectors (small sector numbers “0” to “29” are sequentially assigned to these 30 small sectors). Data for six sectors). The data recording area Db of the large sector is formed by dividing one track into five small sectors. And large sector recording area D
b includes five data recording areas Ds for one small sector, as shown in FIG. 8B.

The data recorded in the data recording area Ds for one small sector is not the data itself in small sector units shown in FIG. 6 but is included in the large sector recording area Db as shown in FIG. 8C. The data of the segment units of the small sectors are mixed. That is, looking at the data of five sectors with small sector numbers “0” to “4”, for example, as shown in FIGS. 8B and 8C, the data of the segment unit of the small sector with number “0” is As shown by hatching, the recording area Db is recorded in one discrete segment every five segments over the entire recording area Db having a size of five recording areas Ds.
Also, the data of the segment unit of the small sector with the number “1” is recorded in the segment adjacent to the data of the segment unit of the small sector with the number “0”, skipping every five segments. Similarly, data in the unit of a segment of the small sectors with numbers "2", "3", and "4" are sequentially recorded in the next segment and every five segments.

Recording can be performed in small sector units. When all five small sectors forming a group are recorded, the user data size is 2560 bytes and the sector size is 300 bytes.
The data format of a large sector of 0 bytes (FIG. 7) is completed. In other words, data access in small sector units,
Data can be accessed in units of large sectors, and compatibility can be achieved.

According to the above configuration, data is written every five segments.
The burst error correction length is five times that in the case where data is continuously written in segment units, and data reliability can be ensured even for small sector data.

Incidentally, when the above-mentioned recording method for compatibility between the small sector and the large sector is generalized, the small sector size A and
When compatibility is achieved between large sector sizes nA (n is an integer of 2 or more), recording is performed in one segment for every n segments. It should be noted that data recording may be performed not in units of one segment but in units of i (i is an integer of 1 or more) segments. In this case, recording and reproduction are performed in i segments of (i × n) segments. is there.

Further, not only the sample servo scheme optical disk, as long as the recording medium with a segment equivalent concepts, or more inventions may be applied, not limited to the disc-shaped recording medium.

By the way, when performing data access to a disk-shaped recording medium, since one sector is usually recorded as one block, it is easy to access the data by adding an address to the head of each sector. it can. However, in the case of the data recording method as described above, since data of one sector (small sector) is recorded in a dispersed manner in segment units, even if an address is added to the head of the small sector recording area Ds. It does not make sense (just indicates a break in a small sector), and the method of data access in units of sectors (small sectors) becomes a problem.

For example, it is conceivable to assign a sector address to the leading segment data of the data of each small sector. In the case of the above example, the address assignment position is determined by the recording area Db of the large sector. Is the data position of the first five segments of the small sector recording area Ds, which is very redundant. In addition, since the number of segments only in the leading portion of the small sector recording area Ds increases, there is a disadvantage that another process is required.

An object of the present invention is to provide an optimum method for accessing data recorded by the above-described novel data recording method.

[0020]

In order to solve the above-mentioned problems, according to the present invention, a unit of data access is used.
A small sector is the smallest unit that can be recorded and reproduced on a recording medium.
And divides the data by i times (i is a positive integer) each segment , and divides the data by i times the segment .
In the recording medium, at the recording position that is discrete at every n × i (n is an integer of 2 or more) times of the minimum unit, and at the recording position adjacent to the i-th data of the segment of the m-th small sector. Is a data processing in which data is recorded such that i times the data of the segment of the (m + 1) th small sector is recorded, and data of n pieces of the small sector is recorded as one large sector. in the system, the addresses assigned to each n-number of the small sector, the n-number of small sections
The address set for each data and the small sector number to be accessed are divided by the n, the head of the large sector is detected based on the quotient obtained as a result of the division, and the result of the division is obtained. Provided is a data access method in which access is started from a data position of the segment indicated by a remainder.

[0021]

According to the present invention having the above-described structure, the track number including the data and the data block in n units (corresponding to the large sector described above) are determined by the address set for each of the n data blocks. ) Can be determined on the track. The quotient obtained by dividing the data block number to be accessed by the n indicates the data block number in units of n, and the remainder is the number of the minimum unit data position from the beginning of the data block in units of n. Is shown. Therefore, by accessing from the minimum unit data position, the target data block can be accessed.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a data access method according to the present invention will be described below with reference to the drawings. The embodiment described below is a case where the present invention is applied to a disk recording / reproducing system for recording data by the above-described novel optical disk recording method.

[Description of Disk Recording / Reproducing System and Data Configuration] FIG. 2 is a block diagram of the overall configuration of a disk recording / reproducing system which is an example of an access method according to the present invention. In this example, the optical disk 1 is a rewritable optical disk, for example, a magneto-optical disk. Because of the sample servo system , this optical disc 1
The above-mentioned tide marks are provided as pre-pits for each segment. The optical disc 1 is driven to rotate by a spindle motor 2.
Receives the servo signal from the servo circuit 5 and drives the optical disc 1 to rotate at a constant angular velocity (CAV), for example.

On one side of the optical disk 1, an optical head 3
Is provided. The optical head 3 of the optical disc 1
A magnetic head 6 is provided at a position facing a surface opposite to the surface facing the magnetic head 6. The optical head 3 and the magnetic head 6 are configured to move in the radial direction of the optical disk 1 in synchronization.

The optical head 3 includes a laser light source and a photodetector. The laser light source is driven by a driving signal from a laser driving circuit 4, and the photodetector receives reflected light from the disk 1 to obtain reproduction information. The laser drive circuit 4 also controls the output power of the laser light source of the optical head 3 to generate a laser beam having a larger power during recording than during reproduction. In addition, a servo control signal from the servo circuit 5 is supplied to the optical head 3 so that focus control and tracking control are performed.

An RF signal (high-frequency signal) reproduced from the optical disk 1 by the optical head 3 is supplied to a servo circuit 5 via a head amplifier 11. The servo circuit 5 calculates the R
A focus error, a tracking error, and the like are formed from the F signal.
To form a servo control signal to be supplied to the.

A modulation / demodulation circuit 12 modulates recording data and demodulates reproduction data. A signal detection circuit such as an NRZ binary value detection circuit or a partial response ternary value detection circuit is included in a stage preceding the demodulation. Reference numeral 13 denotes a RAM for temporarily storing data for processing recorded data and reproduced data. 14 is the RAM
13 is a RAM controller that controls writing of recording data to the memory 13 and reading of reproduction data. The exchange of recording data and reproduction data with other external devices is performed by a SCSI interface in this example. Reference numeral 15 denotes a SCSI controller for the SCSI interface.

Recording is performed as follows. That is,
The recording data from the SCSI interface is SCS
It is temporarily stored in the RAM 13 via the I controller 15 and the RAM controller 14. The data is read out appropriately according to an instruction from the system controller 10, supplied to the modulation / demodulation circuit 12, modulated, and supplied to the magnetic head drive circuit 16. Magnetic head drive circuit 16
Drives the magnetic head 6 so as to apply a modulation magnetic field corresponding to the recording data to the optical disk 1 and performs recording. At this time, the above-described servo control is performed, and recording is sequentially performed in units of one segment.

In reproduction, a sample servo
According to the method , data is sequentially read in units of one segment. The reproduction RF signal obtained from the optical detector of the optical head 3 is supplied to a modulation / demodulation circuit 12 through a head amplifier 11 and demodulated.
13 is stored. Then, the data is appropriately transferred to the reproduction data processing unit via the SCSI interface.

Next, the structure of the recording / reproducing data in this system will be described. This data configuration is the same as in the case of FIGS. 6 and 7 described above. That is, the user sector size is 512 bytes / 1 sector for the small sector and 2560 bytes / 1 sector for the large sector. And
The data format of the small sector and the large sector is as shown in FIGS. 6 and 7 described above, and the data of the large sector is composed of five small sectors stacked in the column direction as shown in FIG. Structure. Then, as shown in FIG. 5, on the disk 1, five data recording areas Ds for one small sector constitute a data recording area Db for one large sector. When writing the data of one small sector to the disk 1, the data of one small sector is divided into units of one segment, and the divided 1
Data for each segment is recorded in discrete segments, for example, in one segment every five segments.

FIG. 3 shows a track format in the case of this example. The configuration of the large sector recording area Db, the recording area Ds for the small sector, and the recording area for one segment are exactly the same as those in the above-described example.

That is, as shown in FIG. 3D, the recording area for one segment is composed of a 4-byte servo area, a 1-byte reference area for reproducing clock synchronization, and a 20-byte user data area. Become. Then, as shown in FIG. 3A, one track includes data of 30 small sectors (small sector numbers “0” to “29”) (= data of 6 large sectors). The data recording area Db of the large sector is formed by dividing this one track into five small sectors. Therefore, as shown in FIG. 3B, the large sector recording area Db includes five data recording areas Ds for one small sector.

As shown in FIG. 3C, the data recorded in the data recording area Ds for one small sector is a mixture of the data of the segment units of five small sectors included in the large sector recording area Db. . That is, assuming that five small sectors constituting a large sector have data of, for example, five sectors with small sector numbers “0” to “4”, as shown in FIG. 3B and FIG. Data of the segment unit of the small sector is 5 in the recording area Ds.
Over the entire recording area Db of a size corresponding to the number of pieces, the data is recorded in one segment every five segments, and the data of the segment unit of the small sector of number “1” is In the segment adjacent to the data of the segment unit of the small sector, the data is recorded at intervals of 5 segments. Similarly, numbers “2”, “3”,
The segment unit data of the small sector of "4" is sequentially recorded in the adjacent segment every five segments.

In this case, the leading 5 of each large sector
The data of each segment unit is the data of the head segment unit of each of the five small sectors constituting the large sector.

Recording can be performed in small sector units. When all five small sectors are recorded, a large sector data format having a user data size of 2560 bytes and a sector size of 3000 bytes (FIG. 7) is completed. .
In other words, data access in small sector units and data access in large sector units are possible, and compatibility is achieved.

In this case, as shown in FIG. 3, the area for one segment immediately before the large sector recording area Db includes:
The address of a large sector immediately after this area is recorded. This address is preformatted on the disk 1 in advance. Alternatively, it is recorded when the disc 1 is formatted. Of course, this address may be written at the time of the first data recording.

As shown in FIG. 3E, the data at this address includes a 2-byte track number TNo (a number from the innermost track of the disk 1, for example) and a 1-byte sector number SNo (in the track, The number includes the number of the small sector of which number), a 3-byte parity ECC for error correction for these number data, and 14 bytes of other auxiliary data (ALPC or reference data). As the sector number SNo of the address data, the smallest number of the small sectors included in the large sector to which the address is added at the beginning is assigned. Since a large sector is formed for every five small sectors, the sector number SNo of this address data indicates the order of the large sector in one track. It should be noted that a large sector number indicating the number of a large sector in one track may be recorded as the number SNo.

[Example of Data Access Method] In the present invention, data access is performed in small sector units using the address given to each large sector as described below.

FIG. 1 is a flowchart of data access in this case. That is, first, a target track number Tr and a target small sector number Se are set as addresses for a target small sector (step 101). Next, the target small sector number Se is divided by the number n of small sectors constituting the large sector (recorded at intervals of n segments; n = 5 in this example), and the quotient SE and the remainder R (R <n) )
Is obtained (step 102).

The obtained quotient SE corresponds to a large sector number. The remainder R corresponds to the number of data in segment units from the beginning of the large sector recording area Db. As described above, the data of the first n segments in the large sector recording area Db is the data of the first segment of the n small sectors included in the large sector. Is specified.

Therefore, the track number TNo of the address data and the target track number Tr are searched while being compared and detected, and the track position of the target track number Tr is detected (step 103). Subsequently, referring to the quotient SE, the quotient S in the track of the target track number Tr is read.
The head of the large sector indicated by E is detected (step 1).
04). Next, the segment (the (R + 1) th segment since the segment number starts from “0”) at the position indicated by the remainder R from the beginning of the recording area Db of the large sector is set to the beginning position of the target small sector. Recording or reproduction is started (step 105). This is the end of the access.

For example, when an instruction of (track number “50”, small sector number “14”) is set as a target small sector, since n = 5, 14/5 = 2
Since the remainder is 4, first, (track number "50", large sector number "2") is searched, and recording or reproduction is started from the fifth segment from the beginning of the large sector.

When the above method is generalized, data can be recorded in units of i (i is an integer of 1 or more) segments, so that a small sector size A and a large sector size n
When compatibility is obtained between A (n is an integer of 2 or more),
That is, recording is performed in the (n × i) i segment for each segment. In this case, the large sector number is identified by the division Se / n in step 102, but the start of access is counted from the beginning of the large sector (i ×
(R + 1) -th segment.

[0044] The present invention is not limited to the sample servo scheme optical disk, a recording medium present in the segments and equivalent concepts can be applied if the data having a sector structure of the data distributed. Further, it is not limited to a disk-shaped recording medium.

[0045]

As described above, according to the present invention, a data block serving as a unit of data access is divided into data units i times (i is a positive integer) the minimum unit that can be recorded and reproduced on a recording medium. And the minimum unit i
Each time the data is doubled, the minimum unit n
.Times.i (n is an integer of 2 or more), and in a data processing system for recording data of n data blocks so that the recording area is continuous, an address is set for each of the n data blocks. Data access can be performed only by providing an area.

Therefore, it is not required to increase the address due to the distributed recording of the data, and the address is added for every n data blocks. No special processing is required.

[Brief description of the drawings]

FIG. 1 is a flowchart of an example of a data access method according to the present invention.

FIG. 2 is a block diagram of an example of a disk device on which a data access method according to the present invention is implemented.

FIG. 3 is a diagram showing a track format of a disk to which the data access method according to the present invention is applied.

FIG. 4 is a diagram for explaining the sample-servo scheme.

FIG. 5 is a diagram showing a recording pattern on a disc.

FIG. 6 is a diagram showing a data format of a small sector.

FIG. 7 is a diagram showing a data format of a large sector.

FIG. 8 is a diagram showing a track format on a disk according to the data recording method proposed above.

[Explanation of symbols]

 1 Optical disk Db Large sector recording area Ds Small sector data recording area As Servo area Ad Data area

Claims (1)

(57) [Claims] 1. A small sector which is a unit of data access,
The data is divided into i-times (i is a positive integer) data segments each of which is a minimum unit recordable / reproducible on a recording medium, and i-times data units of the segment are stored in the recording medium, In the recording position at intervals of n × i (n is an integer of 2 or more) times the minimum unit, the recording position adjacent to the i-th data of the segment of the m-th small sector is m
The data is recorded such that i times the data of the segment of the + 1st small sector is recorded, and the data of n small sectors is recorded as one large sector. in a data processing system, the n of the assigned addresses for each small sector, the n number of address set for each small sector, a small sector number to be accessed is divided by the n, the result was the division obtained detecting the beginning of the large sector based the quotient is, the cell indicated by the remainder obtained as a result of the division
A data access method in which access is started from the data position of the segment .