JPH0667808A - Multiplexed disk control device - Google Patents

Abstract

PURPOSE:To speed up an access and to improve reliability in a multiplexed disk control device for storing the same contents in plural disks. CONSTITUTION:An I/O means 4 executes striping type I/O by using a data area in either one of two disk devices A, B respectively divided into data areas and backup areas and a copying means 5 copies the contents of the data area in one disk to a backup area of the other disk. When a disk failure is generated, a disk switching means 3 separates the failed disk. The I/O means 4 continuously executes data I/O by using the data area and the backup area of the normal disk.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dual disk controller for inputting / outputting to / from two disk devices by a striping method.

[0002]

2. Description of the Related Art There is a dual disk system in which the reliability of the devices is improved by storing the same information in two disk devices to provide redundancy. Specifically, if one of the disk devices fails, there is a type that continues operation with only a normal disk device, or a type that prepares an alternative disk instead of the failed disk device and continues processing. is there. These make it possible to minimize damage such as data loss and system down.

As a technique related to such a disk system, for example, Japanese Patent Laid-Open No. 2-136943 discloses that the volume label and the file directory file of the duplicated disk device are separately updated to improve the utilization efficiency. A disk file updating method has been proposed that prevents deterioration and ensures safety. Further, in Japanese Laid-Open Patent Publication No. 3-204023, since write processing is performed for two magnetic storage devices, the first magnetic storage device is processed by a write command, and a copy command linked to the command is used. There has been proposed a dual control system for a magnetic storage device, which easily realizes dual write processing by performing write processing on the second magnetic storage device.

[0004]

However, in the conventional disk control device of the dual disk system, since only one disk device is targeted for both reading and writing of data, it is possible to have a plurality of disk devices. However, since only one disk device is active at any given time, it was not useful for improving access performance. Incidentally, the above-mentioned Japanese Patent Laid-Open No. 2-1
The methods proposed in Japanese Patent No. 36943 and Japanese Unexamined Patent Publication No. 3-204023 are intended to improve utilization efficiency and ensure safety, and do not consider improvement in access performance.

It is an object of the present invention to provide a multiplexed disk control device which has a high access speed and improved reliability.

[0006]

In order to solve the above problems, in a multiplexed disk control device according to the present invention, a plurality of storage areas are divided or distributed into a first storage area and a second storage area. In a multiplexed disk control device having the same disk and storing the same contents in the plurality of disks, an input / output unit for performing striping type input / output to the first storage areas of the plurality of disks; Data transfer means for transferring the contents of the storage area of the disk to the second storage area of another disk, and disk switching means for disconnecting the disk related to the failure when a failure occurs in the plurality of disks, When a failure occurs, the first storage area and the second storage area of the remaining normal disk
And a control means for continuously inputting / outputting data by using the storage area.

[0007]

For example, when a duplicated disk system is constructed with two disk devices A and B, if both disk devices are in a normal state, the input / output means has the first storage area and the second storage area of each disk. Striping input / output is performed using areas. In parallel with this, the data transfer means transfers the portion changed in the first storage area of the disk device A to the second storage area of the disk device B and changes it in the first storage area of the disk device B. The created portion is transferred to the second storage area of the disk device A. In this way, by performing striping type input / output by using two disk devices and mutually copying the backup of each other to the other disk device, at least two disk devices are always in the active state. Therefore, the access speed can be increased.

When a failure occurs in the disk device B, the disk switching means disconnects the disk device B from the system and connects only the disk device A. Then, the control means uses the first storage area and the second storage area of the normal disk device A to perform striping type input / output. According to this, even if a failure occurs in one of the disks, the input / output processing can be continued.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a multiplexed disk control device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration when the multiplex disk control device according to the present invention is applied to a dual disk system. This system includes a host device 1 that issues an I / O request to an external storage device (disk device), and a disk controller 2 that controls the disk device A and the disk device B in response to a request from the host device 1.
And a disk device A and a disk device B.

The disk device A has a data area 6 in which original data is stored and a backup area 8 for copying the data area 7 of the disk device B. The data area and the backup area may be divided as one continuous area,
They may be arranged in a dispersed manner.

The disk device B has a data area 7 in which original data is stored and a backup area 9 for copying the data area 6 of the disk device A. The data area and the backup area may be divided as one continuous area,
They may be arranged in a dispersed manner.

The disk controller 2 is a disk device A /
When a failure occurs in either of B, the disk device related to the failure is disconnected from the system, and the disk switching is performed to continuously input / output data by using the data area and backup area of the normal disk device. At the request of the means 3 and the host device 1, the disk device A /
From the input / output means 4 for performing striping type input / output to the data area B, and the copy means 5 for copying the output data or the contents of the data area changed by the input / output means 4 to the backup area of the other disk device. It is configured.

Next, the operation of the above dual disk system will be described. 2 and 3 are block diagrams for explaining the operation during system operation corresponding to FIG. 1. FIG. 2 shows a normal state, and FIG. 3 shows a state in which one disk device has a failure. In both figures, stripe selectors 10 to 13 are connecting means for connecting to the data area and backup area of each disk device, and are turned on / off by the disk switching means 4. Others, Figure 1
The same parts as are denoted by the same reference numerals.

In FIG. 2, when an I / O request is sent from the host computer 1 to the disk controller 2, the input / output means 4 performs striping input / output according to the I / O request. In FIG. 2, the disk selector 4 selects the stripe selectors 10 and 12, and the data area 6 and the data area 7 are selected.
Is connected. Since both the disk device A and the disk device B are in a normal state, striping input / output is performed using the data area 6 of the disk device A and the data area 7 of the disk device B. In parallel with this, the copying means 5 copies the changed part in the data area 6 of the disk device A to the backup area 9 of the disk device B, and copies the changed part in the data area 7 of the disk device B to the disk device. Copy to the backup area 8 of A.

When a failure occurs in one of the disk devices, the disk switching means 3 controls the stripe selectors 10 to 13 to turn off the stripe selector of the disk device on the failed side, and the disk selector on the normal side. Turn on the stripe selector. At the same time, the copying means 5 is instructed to stop the copying operation. In FIG. 3, the stripe selectors 12 and 13 of the failed disk device B are separated and the disk device A
Striping input / output is performed between the data area 6 and the backup area 8. As a result, even if one of the disk devices fails, the input / output processing can be continued.

Disk controller 2 in case of failure
The processing procedure of is shown in the flowchart of FIG. First, when the occurrence of a failure is detected in step 101, step 102
At step 103, the stripe selector of the disk device on the failed side is turned off, and at step 103, the stripe selector of the disk device on the normal side is turned on. Step 104
Then, the copying means is instructed to stop the copying operation, and in step 105, striping input / output is continued using the normal data area and backup area of the disk device.

An example of the arrangement of the data area and the backup area in the disk device is shown in FIGS. In both figures, n represents the number of striping blocks of the disk device. FIG. 5 shows the outer peripheral side of the disk (cylinders 0 to 2).
/ N-1), the data area, the inner circumference side (cylinder 2 / n ~
(n-1) shows an example in which the backup area is divided and arranged. In this way, the reliability of the system can be further improved by taking the data area on the outer peripheral side where the error rate is small.

FIG. 6 shows an example in which the data area and the backup area are alternately dispersed and arranged for each striped size. The data area is distributed and arranged as a plurality of sub-data areas. With such an arrangement, when a failure occurs, the disk on the normal side can be viewed as a plain image without striping, so that it is possible to access at higher speed.

The above-described embodiment is an example of a duplex system using two disks, but it is also applicable to a duplex system using three or more disks.

[0021]

As described above, in the multiplexed disk control device according to the present invention, striping input / output is performed by using the data areas of a plurality of disks divided into the data area and the backup area, respectively. Since the contents of their own data areas are mutually copied to the backup area of the other disk, at least 2
It becomes possible to set each disk device in an active state, and it is possible to speed up access.

Further, when a disk failure occurs, the failed disk is disconnected, and data is continuously input / output by using the normal disk data area and backup area. Therefore, the failure occurs. Even in such a case, the processing can be continued as it is, so that the reliability of the system can be further improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration when a multiplex disk control device according to the present invention is applied to a dual disk system.

FIG. 2 is a block diagram illustrating an operation when the system is operating.

FIG. 3 is a block diagram illustrating an operation when the system is operating.

FIG. 4 is a flowchart showing a processing procedure of the disk control device when a failure occurs.

FIG. 5 is an explanatory diagram showing an arrangement example of a data area and a backup area in a disk device.

FIG. 6 is an explanatory diagram showing an arrangement example of a data area and a backup area in a disk device.

[Explanation of symbols]

2 ... Disk control device, 3 ... Disk switching means, 4 ...
Input / output means, 5 ... Copying means, 6, 7 ... Data area, 8,
9 ... Backup area

Claims (1)

[Claims] 1. A multiplexed disk control device comprising a plurality of disks each of which has a storage area divided into a first storage area and a second storage area, and storing the same contents in the plurality of disks. Input / output means for performing striping type input / output to / from the first storage area of another disk; data transfer means for transferring the contents of the first storage area to a second storage area of another disk; Disk switching means for disconnecting a disk related to this failure when a failure occurs in one of the disks, and the first storage area and the second storage area of a normal disk when the failure occurs And a control means for continuously inputting / outputting data, and a multiplexed disk control device.