JPH04339372A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To reduce the number of times of correction and to improve processing efficiency by not correcting the respective positional deviation of data heads but collecting the heads with close positional deviations, dividing them into several blocks and correcting the positional deviation in units of blocks. CONSTITUTION:Plural data heads 3 are divided into several blocks corresponding to the amount of positional deviation with respect to a servo head 4, the correction of positional deviation is not performed between the data heads 3 belonging to the same block and the correction is performed only between the blocks of the data heads 3. In the block division, the conversion is made so that the physical head numbers of the data heads 3 belonging to the same block can be serial logic head numbers in the block. Furthermore, the number of data heads 3 incorporated in each block is made the same.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a magnetic disk device that employs a cylinder surface servo system that controls the positioning of a data head on a recording/reproducing disk based on positional information from a servo disk read out by a servo head. The present invention relates to a magnetic disk device that starts a recording/reproducing operation after correcting a positional deviation of a data head with respect to a servo head when switching. In magnetic disk drives that employ a cylinder surface servo system that positions and controls the data head based on position information from the servo disk, read errors may occur due to misalignment of the data head with respect to the servo head.
The occurrence of errors is an important problem and has a great impact on the system.

[0002] In recent years, large capacity and
There is a demand for higher functionality, and in particular, the track density has become higher in order to achieve large capacity, and slight misalignment of the data head has become a very serious problem. However, it is difficult to eliminate the physical positional deviation of the data head due to mechanical errors depending on assembly accuracy, temperature, etc., and therefore it is necessary to correct the positional deviation of the data head.

0003

2. Description of the Related Art In conventional magnetic disk drives, positional deviation correction of data heads is performed individually for each head. That is, when the magnetic disk device is powered on or at predetermined time intervals after operation, a positional deviation detection process is executed to detect and store the amount of positional deviation of each data head with respect to the servo head, and the gain obtained by this positional deviation detection process is executed. For example, during block access where data heads are sequentially switched at the same cylinder position to read data, each time the data head is switched, the data head is adjusted based on the position shift amount obtained in advance. The read operation is started after the position is corrected.

[0004] This data head positional deviation correction is performed by physically moving the data head by several μm.
A processing time of about 3 ms is required.

[0005]

However, if the positional deviation is corrected for each data head individually, a processing time of 2 to 3 ms is required each time the data head is switched.
There was a major problem in that the throughput on the system decreased. Particularly when processing a large amount of data, multiple tracks must be written or read in succession, but since track switching at this time does not require a seek operation, the head must be positioned at a specific cylinder position. This is often done by switching heads in a state where the

In this case, track n of a certain data head
A write or read operation is performed from the upper sector 0 to the last sector, and then the data head is switched to the second data head and a write or read operation is performed to sector 0 of the next track n+1. However, if it takes 2 to 3 ms processing time to switch the head, the head position has already passed sector 0, and the write or read operation of sector 0 requires one revolution, that is, about 10 ms to 20 ms, which is determined by the number of rotations of the medium. There was a problem in that the processing efficiency on the system decreased due to waiting for rotation. The present invention has been made in view of these conventional problems, and an object of the present invention is to provide a magnetic disk device that improves processing efficiency by minimizing head switching accompanied by positional deviation correction to the necessary minimum. shall be.

[0007]

[Means for Solving the Problems] FIG. 1 is a diagram illustrating the principle of the present invention. First, as shown in FIG. 1(a), the present invention provides at least one
One disk surface is used as a servo disk 2 that records rotational position information, and the rest is a data disk 1 for recording and reproducing.
The data head 3 provided on the data disk 1 and the servo head 4 provided on the servo disk 2 are made movable in the direction across the medium track, and when the data head 3 is switched, the positional deviation of the data head 3 with respect to the servo head 4 is prevented. The target is a magnetic disk device that starts recording/reproducing operation after correcting the error.

In the present invention for such a magnetic disk device, a plurality of data heads 3 are connected to a servo head 4.
Positioning control that divides the data into multiple blocks according to the amount of positional deviation from the block, and corrects the positional deviation only when switching to the data head of another block without correcting the positional deviation when switching between data heads belonging to the same block. The present invention is characterized in that means 5 is provided.

Further, the positioning control means 5 is characterized in that, as shown in FIG. 1(b), the physical head numbers of the data heads belonging to the same block are converted into consecutive logical head numbers within the block. . Furthermore, in order to cope with the case where the host device plans to connect a magnetic disk device that does not have a function of positional deviation correction, the positioning control means 5 is configured to control each block as shown in FIG. 1(c). By setting the number of data heads in the block to be the same and sequentially assigning logical cylinder numbers starting from the first block, the repetition of the same physical cylinder number in each block is converted to a different continuous logical cylinder number for each block, and different At the time of head switching accompanied by correction of positional deviation between blocks, the correction of positional deviation accompanying head switching is made to appear to a higher-level device as a seek operation by switching logical cylinder numbers, and the higher-level device is made to wait for a seek.

0010

[Function] According to the magnetic disk device of the present invention having such a configuration, the following function can be obtained. Even if positional deviation correction is performed in response to increased track density, in order to minimize system throughput, the present invention does not perform positional deviation correction for each data head individually.
By gathering heads with similar amounts of positional deviation and dividing them into several blocks, and performing positional deviation correction on a block-by-block basis, it is possible to reduce the number of times positional deviation correction is performed.

[0011] By correcting the positional deviation in units of blocks, the operation for correcting the positional deviation is not necessary for data heads within a block, and the processing time required for head switching is reduced from about 2 to 3ms to about 300ms. It can be shortened to 5 to 15 μs. Also, when performing continuous data processing,
Since it is necessary to make the head numbers within a block continuous, non-contiguous physical head numbers are converted into continuous logical head numbers by dividing into blocks.

[0012] By making the head numbers within a block consecutive in this way, head switching becomes easy even when processing a large amount of data continuously. Furthermore, if the host device is planning to connect a magnetic disk device that does not have a head misalignment correction function, connecting a magnetic disk device that performs misalignment correction when switching heads to this host device will reduce the head switching time. Because of the large difference, normal control of the magnetic disk device may not be possible.

In order to solve this problem, the number of heads in each block is the same, the physical cylinder number is converted to a logical cylinder number according to the number of blocks, and the logical cylinder number is switched when switching heads between blocks. Even if the device performs a seek operation and it takes time to correct the positional deviation due to head switching, the host device enters a seek wait state and can apparently be used by the host device as a magnetic disk device without a positional deviation correction function.

[0014]

Embodiment FIG. 2 is a block diagram showing an embodiment of the present invention. In FIG. 2, the magnetic disk device is roughly divided into a disk control device 10 and a disk drive device 20. The disk control device 10 is provided with a control processor section 11, which controls the entire device. Control processor section 11
An interface unit 12 with a host device, a data transfer buffer 13, a serial/parallel converter 14, and a drive interface unit 15 are provided for the controller.

The control processor section 11 receives and analyzes control commands from the host device, and notifies the disk drive device 20 of the analysis results. It also performs format control during read/write, generates ECC, detects data errors, etc. The disk drive device 20 includes an interface control section 21 with the disk control device 10 and a data modulation/demodulation section 2.
2. Read/write control section 23, read/write circuit 2
4, a servo control section 25 and a positioning control section 26 are provided.

Note that the data modulation/demodulation section 22 and the read/write circuit section 24 constitute a VFO circuit. 30 is a disk enclosure, in which a plurality of data disks 1 for recording and reproduction and one servo disk 2 are mounted on the rotating shaft of a spindle motor 31, and a data head 3 is arranged for the data disk 1; A servo head 4 is arranged with respect to the servo disk 2.

The data head 3 and servo head 4 are VC
It is moved by M32 in a direction across the tracks of disks 1 and 2. FIG. 3 shows a head drive mechanism used in disk enclosure 30. In FIG. 3, 33 is a rotating shaft, a VCM coil core 34 is arranged behind the rotating shaft 33, and a plurality of arms 35 extend in front. A data head 3 is attached to the tip of each arm 35 via a gimbal 36, and a servo head 4 is attached at the center of the plurality of data heads 1.

A head IC 36 is mounted on the side of the arm 35. This head IC 36 includes a head switching circuit. Referring again to FIG. 2, the positioning control unit 25 of the disk drive device 20 stores the amount of positional deviation of the data head 3 with respect to the servo head 4 determined in advance for each data head 3, and performs head switching. At this time, a write or read operation is started after the head position is corrected by the corresponding amount of positional deviation.

Furthermore, the positioning control section 25 controls the data head 3.
are divided into blocks according to the amount of positional deviation, and positional deviation correction is not performed when switching heads within the same block, but only when switching to a head in a different block. FIG. 4 is an explanatory diagram showing a first embodiment of block division of a data head according to the present invention.

In FIG. 4, data heads 3 indicated by head numbers HD0 to HDn+1 are arranged above the central servo head 4, and data heads 3 indicated by head numbers HDn+2 to HDm+1 are arranged below.
A data head 3 shown by is arranged. In addition, HD0~H
Dm+1 is a physical head number. Upper head number H
The data heads 3 of D0 to HDn+1 are displaced to the left with respect to the servo head 4, and the data heads 3 of lower head numbers HDn+2 to HDm+1 are displaced to the right of the servo head 4.

In this embodiment, head numbers HD0 to HDm
The +1 data head 3 is divided into two blocks, a first block and a second block, with the servo head 4 as a boundary. When the blocks are divided in this way, the average value of the individual positional deviations of the data heads 3 belonging to each block is used as the positional deviation amount of the data head 3 with respect to the servo heads 4 of the first and second blocks. The positional deviation is corrected when head switching is performed from another block. Head switching between different blocks takes 2 to 3 ms as before.
It takes some time.

After that, positional deviation correction is not performed for head switching within the same block. Therefore, the time required to switch heads within the same block is approximately 5 to 15μ.
It can be shortened to s. Here, the timing of blocking in the first embodiment may be only once at the time of initializing the device, or may be performed periodically when the device is used.

FIG. 5 shows the second block division in the present invention.
FIG. 3 is an explanatory diagram showing an embodiment of the present invention, taking as an example a case where the positional deviation of the data head 3 with respect to the servo head 4 occurs randomly without directionality as shown in FIG. In such a case, for example, the first
It is divided into two blocks: a block and a second block in which the data heads 3 that have shifted to the right side are collected.

[0024] In such block division, the physical head numbers of the data heads 3 belonging to each block are no longer consecutive, and block access, in which data is written or read by sequentially switching the heads with the head positioned in a specific cylinder, becomes difficult. Head designation becomes complicated. Therefore, as shown in Figure 6, a conversion table is created in which logical head numbers with continuity are assigned to the physical head numbers of the first and second blocks, which are non-contiguous. Accept as head number,
Use a conversion table to convert to a physical head number and perform head switching.

Here, the timing of blocking in the second embodiment is assumed to be only once at the time of initializing the device, since it is necessary to determine the logical head number as shown in FIG. 4 and 5, the number of heads belonging to the first and second blocks is the same, but this is for convenience of explanation; in reality, the number of heads belonging to each block is the same according to the rules for dividing blocks. The number is determined appropriately.

FIG. 7 shows a conventional cylinder and head configuration associated with block division to enable the use of the magnetic disk device of the present invention in a host device to which a magnetic disk device without a positional deviation correction function is planned to be connected. It is an explanatory diagram shown in comparison with. The magnetic disk device of the present invention is based on the premise that positional deviation correction is performed at the time of head switching, and this positional deviation correction requires a processing time of about 2 to 3 ms. Therefore, in the host device to which the magnetic disk device of the present invention is connected, access management is performed with consideration given to the processing associated with positional deviation correction at the time of head switching. For example, it takes about 2 to 3 ms to correct the positional deviation after switching the head.
During this time, if sector 0 of the next track is passed, the system waits for one rotation, and the host device performs access management to allow this rotation waiting as a normal operation.

On the other hand, if a magnetic disk device equipped with the positional deviation correction function of the present invention is connected to a host device that is scheduled to use a magnetic disk device without a positional deviation correction function, the positional deviation after head switching will be reduced. When waiting for rotation due to correction, the host device recognizes a time-over error and determines that the process has ended abnormally, making it impossible to control the process normally. Therefore, in the third embodiment of the present invention, when switching heads between blocks in which head positional deviation correction is performed, the head switching is shown to the host device as a seek operation, and the positional deviation correction is performed by waiting for the seek. It is possible to avoid the accompanying abnormal processing of the host device.

FIG. 7(a) shows the correspondence between a conventional head configuration and a cylinder configuration formed by an axial chain of disk tracks. In this example, the data head 3 is composed of 20 pieces with physical head numbers HD0 to HD10, and the number of cylinders is physical cylinder numbers CYL0000 to CYL0.
It consists of 100 cylinders of 099.

FIG. 7(b) shows the head and cylinder configuration of the present invention when FIG. 7(a) is divided into four blocks. First, when dividing into four blocks, the number of heads included in each of the first to fourth blocks is the same. In this case, each block is assigned five heads.

As shown on the right side, the physical cylinder numbers in this block division are the same physical cylinder number CYL0000 in each of the first to fourth blocks.
~CYL0099 is repeated. These physical block numbers are shown on the left, from the 1st block to the 4th block.
The blocks are converted into consecutive logical cylinder numbers CYL0000 to CYL0399 that increase in order to obtain the next conversion table. [Physical cylinder number] [Logical cylinder number]
1st block CYL0000~0099
CYL0000~0099 2nd
Block CYL0000~0099
CYL0100~0199 3rd block CYL0000~0099
CYL0200~0299 3rd block CYL0000~0099 C
YL0300 to 0399 By using such a conversion table between physical cylinder number and logical cylinder number, even when switching heads within the same physical cylinder number,
When switching to a head in a different block, the logical cylinder number changes, and because the logical cylinder numbers are different, the host device recognizes it as a seek operation even though the head switching is actually at the same cylinder position. I will do it.

FIG. 8 shows the physical cylinder number C in FIG.
The operation when the data head is sequentially switched from physical head number HD00 to HD19 with the data head positioned at YL0000 is shown in FIG. 8(a) when the physical cylinder number is used as is, and FIG. This figure shows the cases in which the conversion table b) is used. In FIG. 8(a), the logical cylinder number CYL0000 becomes the physical cylinder number CYL0000 as it is, and positional deviation correction is not required for head switching within a block, but positional deviation correction is required for head switching between different blocks. .

For this reason, the magnetic disk device of the present invention cannot be connected to a host device to which a magnetic disk device without a positional deviation correction function is planned to be connected. On the other hand, when the conversion table shown in FIG. 8(b) is used, the first
For blocks, the logical cylinder number CYL0000 remains the physical cylinder number CYL0000, but for the second, third, and fourth blocks, the logical cylinder numbers CYL0100, CYL02 are different.
00, CYL0300, and the host device recognizes it as a seek operation because the cylinder number changes, and normally treats the delay in processing due to positional deviation correction performed by switching heads between blocks that change to the logical cylinder number as a seek wait. Can be processed.

Therefore, even if a host device is scheduled to be connected to a magnetic disk device that does not have a positional deviation correction function, it is possible to connect the magnetic disk device of the present invention by providing the conversion table shown in FIG. 7(b). be able to.

[0034]

As explained above, according to the present invention, by correcting the positional deviation of the data head in units of head blocks, it is possible to achieve stable reading operations by correcting the positional deviation and shorten the processing time for head switching. can do. Furthermore, since logical head numbers are used that are consecutive physical head numbers within a block, processing for accessing a large amount of data by switching heads can be made more efficient.

Furthermore, by converting each block into a different logical cylinder number, positional deviation correction caused by head switching between blocks can be made to appear as a seek operation to the host device.
By pretending to be a magnetic disk device that does not have a misalignment correction function, it is possible to use it as is in a host device that uses a magnetic disk device that does not have a misalignment correction function, without changing the control conditions of the magnetic disk device. High versatility can be obtained.

[Brief explanation of drawings]

[Fig. 1] Diagram explaining the principle of the present invention

[Figure 2] Configuration diagram of an embodiment of the present invention

FIG. 3 is an explanatory diagram of the head drive mechanism of the present invention.

FIG. 4 is an explanatory diagram of block division of the data head of the present invention.

FIG. 5 is an explanatory diagram showing another block division of the data head of the present invention.

[Fig. 6] An explanatory diagram of conversion between a physical head number and a logical head number for block division in Fig. 5.

[Fig. 7] An explanatory diagram showing the cylinder and head configurations associated with block division when the host device plans to connect a magnetic disk device that does not have a positional deviation correction function in comparison with the conventional one.

[Fig. 8] An explanatory diagram of positional deviation correction when the head is sequentially switched from HD0 to HD19 in Fig. 7.

[Explanation of symbols]

1: Data disk 2: Servo disk 3: Data head 4: Servo head 5: Positioning control means 10: Disk control device 11: Control processor section 12: Interface control section 13: Data transfer buffer 14: Serial/parallel converter 15: Drive interface section 20: Disk drive device 21: Interface control section 22: Data modulation/demodulation section 23: Read/write control section 24: Read/write circuit 25: Servo control section 26: Positioning control section 30: Disk enclosure 31: Spindle motor 32: Voice coil motor (VCM) 33: Rotation axis 34: VCM coil core 35: Arm 36: Gimbal 36: Head IC

Claims (3)

[Claims] Claims: 1. At least one disk surface of a plurality of disks mounted on a spindle shaft is used as a servo disk (2) on which rotational position information is recorded, and the rest is used as a data disk (1) for recording and reproducing. Disc (1
The data head (3) provided on the servo disk (2) and the servo head (4) provided on the servo disk (2) are movable in the direction across the medium track, and when the data head (3) is switched, the servo head (4) is provided on the servo disk (2). In a magnetic disk device that starts recording and reproducing operation after correcting the positional deviation of the data head (3) with respect to the plurality of data heads (4), the plurality of data heads (3)
3) is divided into multiple blocks according to the amount of positional deviation with respect to the servo head (4), and when switching between data heads belonging to the same block, the positional deviation is not corrected and switching to the data head of another block is performed. A magnetic disk device characterized by being provided with a positioning control means (5) that corrects positional deviation only occasionally. 2. The magnetic disk drive according to claim 1, wherein the positioning control means (5) converts physical head numbers of data heads belonging to the same block so that they become consecutive logical head numbers within the block. A magnetic disk device characterized by: 3. The magnetic disk device according to claim 1, wherein the positioning control means (5) sets the number of data heads in each block to be the same and allocates logical cylinder numbers in order from the first block. Converts the repetition of the same physical cylinder number in each block to a different consecutive logical cylinder number for each block, and when switching heads with correction of positional deviation between different blocks, switching the logical cylinder number allows the host device to A magnetic disk device characterized in that correction of positional deviation caused by head switching is made to look like a seek operation and wait for a seek.