JPH05289827A - Disk controller - Google Patents

Abstract

(57) [Abstract] [Purpose] When the data of the disk drive during online operation is copied to another disk drive by the disk controller, the moving amount of the disk head accompanying the copy operation is reduced and the copy time is shortened. [Structure] The disk controller manages the position information of the non-copy area and the head position information on the disk drive to be copied, and the head of the copy destination drive is always positioned at the same position as the copy source drive. In this case, a means for determining the position of the non-copy area where the head movement time is the shortest from the position information of the non-copy area and the head position information and restarting the copying process from the area of the position is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk control device, and more particularly to a copy control system for copying data on a disk drive connected to the device to another disk drive connected to the device.

[0002]

2. Description of the Related Art As the field of application of computer systems expands, the number of cases in which system nonstop performance is required is increasing. One of the conditions for achieving non-disruptiveness of the system is that maintenance can be performed online.If the maintenance target is a disk drive, replace the disk drive with a spare disk drive in advance. Or use it for multiplexing,
Alternatively, it is necessary to perform maintenance of the original disk drive after copying the stored data to the spare disk drive during online operation. In either case, while copying the data on the disk drive to another disk drive, it is a problem that the host computer can perform data access to the disk drive and copy processing can be executed in a short time. In the technique disclosed in Japanese Patent Laid-Open No. 64-33770, data is sequentially copied from a copy source disk drive to a copy destination disk drive, and the pointer memory stores the extent to which this copying is completed. When the data access to the copy source disk drive occurs during the copy process, the copy process is interrupted. If the data access is read, the read from the copy source disk drive is executed, and if the data access is write, , The address is for the copied address It is determined whether or not the by using the pointer memory of,
If it is for a written address, it writes to the copy source and copy destination disk drives, and if it is for an address that has not been copied, it only writes to the copy source disk drive and then the interrupted copy process. The above-mentioned problem is solved by restarting.

[0003]

In the above-mentioned prior art, even if the address for which the copying process is completed is managed in the pointer memory and the copying process is interrupted and the data access is executed by the host computer, after the data access is completed. The copying process can be restarted, and the host computer writes the data to the copied address of the copying source disk drive to the copying destination disk drive as well, so that the copying process can be performed once over the entire disk drive. The feature is that it is done.

However, the inventor has found that the above-mentioned prior art has the following problems. The above technology does not have a strategy for determining the copy restart position when the copy process is restarted. If the simplest method of restarting the copy from the position where the previous copy was interrupted was adopted, the host that caused the copy process to stop Due to the execution of data access by the computer, the head of the copy source disk drive may have moved from the position where copying was interrupted last time.
Although it is necessary to restart the copying process after positioning the head to the position where the copying was interrupted last time, under the situation where the host computer frequently accesses the data, the data access will occur even during the positioning of the head. This may cause a delay in the progress of the copying process and a reduction in the execution speed of data access by the host computer.

SUMMARY OF THE INVENTION An object of the present invention is to provide a disk control device having a copy restart position determining strategy for reducing the head positioning time when the copy process is restarted.

[0006]

In order to achieve the above-mentioned object, a disk controller manages position information of an uncopied area on a disk drive to be copied and position information of a head, and a copy destination. The head of the drive is always positioned at the same position as the copy source drive, and the position of the uncopied area with the shortest movement time of the head is obtained from the position information of the uncopied area and the head position information, and the position of that position is determined. A means for restarting the copying process from the area is provided.

[0007]

In the disk control device of the present invention described above, the waiting time for positioning the head is minimized when the copying process of the disk drive is restarted, and as a result, the copying time is reduced. The probability that data access to the disk drive will occur is reduced, and the delay in executing data access due to waiting for the positioning completion is reduced.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a disk controller which is an embodiment of the present invention.

The disk control device 200 comprises, for example, a central processing unit which is the center of a general-purpose computer system, and a host device 100 including a channel for controlling data exchange with the outside, instead of the central processing unit, and a disk. The I / O control circuit 201 and the head position management memory 2 are connected as components to the drives 301 and 302.
02, an uncopied area management memory 203, and an operation panel 204. The input / output control circuit 201 is the host device 10.
It controls data write / read processing to / from the disk drive requested from 0 and copy processing of the disk drive instructed from the operation panel 204. The head position management memory is used to record the cylinder number of the movement destination when the input / output control unit 201 instructs the disk drives 301 and 302 to position the head. The uncopied area management memory is a memory for recording the number of tracks for which the copying process by the input / output control circuit 201 is completed, for each cylinder of the disk drive to be copied, and has the structure shown in FIG. There is. The contents of the uncopied area management memory are updated each time the input / output control circuit 201 copies one track.

The operation of the disk controller of this embodiment is as follows.

When the control panel 204 gives an instruction to copy the contents of the disk drive 301 to the disk drive 302, this instruction is accepted by the input / output control circuit 201, and the input / output control circuit 2 is started prior to the start of the copying process.
01 clears all the fields of the number of copied tracks in the non-copy area management memory to record that all tracks of all cylinders are in the non-copy state. Next, the copying process is carried out in the following procedure.

The input / output control circuit 201 reads the cylinder number of the head of the disk drive 301 from the head position management memory. Next, the number of copied tracks corresponding to the cylinder in the uncopy area management memory is read,
By comparing this with the number of tracks per cylinder, it is determined whether or not there are uncopied tracks in the cylinder. If an uncopied track remains, the data of the track having the smallest track number among the uncopied tracks is copied to the same track of the disk drive 302, and when the copying is completed, a copy corresponding to the cylinder of the uncopied area management memory. Add 1 to the number of completed tracks. If there are no uncopied tracks, read the number of copied tracks in the uncopied area management memory for cylinders other than the cylinder in which the head is located, and compare this with the number of tracks per cylinder. By checking whether there is an uncopied track, position the heads of the disk drives 301 and 302 to the cylinder in which the uncopied track found first, and record the cylinder number in the head position management memory, and then discover The data of the track having the smallest track number among the uncopied tracks of the cylinder is copied to the same track of the disk drive 302, and when the copying is completed, the number of copied tracks corresponding to the cylinder where the head of the uncopied area management memory is located is set. Add 1 All the data in the disk drive is copied by repeating the above-mentioned copying process until the number of copied tracks in all cylinders of the uncopied area management memory becomes equal to the number of tracks per cylinder.

During this copying process, the host device 100 sends a disk drive 301 to the disk controller 200.
When the writing or reading of data to or from the disk is requested, the disk controller 200 finishes copying the track being processed and sets the number of copied tracks corresponding to the cylinder in which the head of the uncopied area management memory is located to 1. After the addition, the copy process is interrupted and the requested data is written or read.

At this time, if the request is to read data, the I / O control circuit 201 instructs the disk drives 301 and 302 to position the head on the cylinder in which the desired data is stored, and the disk drive 301 When the positioning of the head is completed, the target data is read and transferred to the host device, and at the same time, the cylinder number in which the head is positioned is recorded in the head position management memory.

On the other hand, when the request from the host device 100 is to write data, the input / output control circuit 201 instructs the disk drives 301 and 302 to position the head on the cylinder where the desired data is to be written,
Next, the number of copied tracks of the cylinder in the uncopied area management memory is read and compared with the track number of the writing destination of the data requested by the upper level device 100 to determine whether the writing destination track is copied or not copied. judge. If the data write destination track requested by the higher-level device 100 has already been copied, the disk drive 301
When the positioning of the heads 302 and 302 is completed, the data received from the higher-level device is written to both disk drives, and if the track to which the data requested by the higher-level device 100 is written is not copied, the disk drive 30
When the positioning of the head of No. 1 is completed, the data received from the host device is written to the disk drive 301.
When the writing is completed, the cylinder number in which the head is positioned is recorded in the head position management memory.

When the data write or read request from the host device 100 is interrupted, the input / output control circuit 201
Restarts the copying process again and realizes full copying of the disk drive.

The time until the copying of one track is completed when the copying is restarted can be expressed by the following formula.

Copying time for one track = head positioning time + average rotation waiting time + data copying time In the method described in this embodiment, a data writing or reading request from the host device during copying occurs in the entire disk. If it occurs randomly across, for example, copying from the innermost (or outermost) cylinder of the disk to the outermost (or innermost) cylinder in sequence,
When the copying process is interrupted by a data writing or reading request from the host device, the head positioning time at the time of resuming copying can be shortened, and as a result, the copying time can be shortened, as compared with the method of restarting the copying process from the interrupted track. .. Further, as described in the present embodiment, when the data writing or reading request from the host device during the copying process to the copying source disk drive is made to wait until the copying of the track being processed is completed, the copying time is shortened. As a result, the probability that a data write or read request from the host device to the copy source disk drive will occur during the copy process is reduced, and the processing delay of the request from the host device can be reduced. This method is effective especially when data writing or reading requests from the host device to the copy source disk drive occur frequently and at random positions on the disk.

[0020]

As described above, according to the present invention, in the copy processing of the disk drive by the disk controller,
By reducing the amount of head movement for copying, there is an effect of shortening the copying processing time and an effect of reducing the processing delay of writing and reading requests from the host device to the copying target disk drive that occur during the copying processing.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a disk control device that is an embodiment of the present invention.

FIG. 2 is a structural diagram of an uncopied area management memory in the embodiment of the present invention.

[Explanation of symbols]

 Reference numeral 100 ... Host device, 200 ... Disk control device, 201 ... Input / output control circuit, 202 ... Head position management memory, 203 ... Uncopied area management memory, 204 ... Control panel, 301 ... Disk drive, 302 ... Disk drive.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiro Usami 2880 Kunifu, Odawara-shi, Kanagawa Hitachi Computer Computer Co., Ltd. (72) Inventor Hisahiro Kasahara 2880 Kozu, Odawara-shi, Kanagawa Hitachi Computer Equipment Co., Ltd.

Claims (1)

[Claims] 1. A plurality of disk drives are connected to a higher-level device that makes a data write or read request to the disk drive, and data is written to the disk drive according to a data write or read request from the higher-level device. Alternatively, the input / output control for reading and reading, one of the disk drives as the copy source drive, and the other as the copy destination drive are used to divide the entire data recording surface of the disk drive into a plurality of areas. An I / O control unit is provided for reading out data for one area from the copy source drive and writing this data in the same area of the copy destination drive. ,
An uncopied area management memory for storing position information of the uncopied area updated by the input / output control unit, and a head position management for storing the movement destination when the I / O control unit moves the head of the disk drive. A disk controller in a computer system including a memory, wherein the input / output control unit is stored in a head position of the copy destination drive recorded in the head position management memory and in the non-copy area management memory. The position information of the uncopied area is compared, the uncopied area located closest to the head position at that time is searched, the data in this area is copied by the copy control, and this is repeated to repeat the operation of the copy source drive. Means for copying all data to the copy destination drive, and means for copying data from the host device to the copy source drive during operation by the copy means. When a data read request is issued, the input / output control unit stops copying and moves the heads of the copy source drive and the copy destination drive to the position where the data requested by the host device is written. ,
After the requested data is read, the copying data is read again by the copying means, and a data write request is issued from the host device to the copy source drive during the operation of the copying means. , The input / output control unit stops copying, moves the heads of the copy source drive and the copy destination drive to the data writing position requested by the host device, and writes the data writing position requested by the host device. And the position information of the uncopied area recorded in the uncopied area management memory are compared, and if the data write request is for the copied area, the requested data writing is copied to the copy source drive. Execute it for both drives of the destination drive, and if the data write request is for the uncopied area. After executing the write requested data only to the copy source drive, disk controller, characterized in that it again comprises a resume copying the data writing means copying by the copy means.