JP2000305717A - Disk array device and method for quickening disk access - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disk array device capable of quickening a writing operation. SOLUTION: A write cache 10 is validly operated for one hard disk device 9 whose disk access frequency is the highest by taking the statistics of disk access to each of plural hard disk devices 9 of a disk array device 2. At the time of power failure, the write cache 10 is invalidated, and cache data are restored by an RAID function. Thus, the disk access can be quickened by validly operating the write cache.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a disk array device having a write cache.

[0002]

2. Description of the Related Art A RAID (Redundant Arrays of Indepenpen) which has a large storage capacity and a redundancy as a storage device applied to a large-scale device having a high demand for high reliability.
dentDisks) has been developed. In a disk array device, even if one of the hard disk devices constituting the array is stopped due to some failure or the like, the data and parity of the remaining hard disk devices constituting the disk array are used. It can be easily restored to the original state. FIG. 3 shows a configuration of a general disk array device.
The host computer 1 issues a command to the disk array device. The disk array device 2 comprises a disk array controller 3 for controlling a hard disk and a hard disk device 9 for storing data. The hard disk drive 9 includes a write cache 10 acting as a cache and a medium 11 for storing data. In order to speed up disk access to the hard disk device 9, it is conceivable to effectively operate the write cache 10 in the hard disk device 9. However, when a power failure occurs, the power of the system is shut off without the disk array device 2 receiving the shutdown command from the host computer 1. For this reason, the command to write the data of the write cache 10 to the medium 11 is not issued to the hard disk device 9 that has enabled the write cache 10, so that the cache data of the hard disk device 9 is lost without being written to the medium 11.

It is conceivable to provide a backup power supply to protect data, but it is not practical because of the cost and the size of the device. At present, the write cache 10 of the hard disk drive 9 is hardly used in a system requiring reliability, and data is written directly to the medium 11.

[0004]

As described above, in the conventional disk array device 2, the write cache 10 of the hard disk device 9 is hardly used, and the data is written directly to the medium 11. It takes a long time to write and cannot speed up disk access. It is an object of the present invention to provide a disk array device 2 which enables a write cache 10 of a hard disk device 9 to operate and speed up disk access.

[0005]

In order to achieve the above object, the present invention provides a disk array device having a plurality of data storage media devices for recording data, wherein a predetermined one of the plurality of data storage media devices is provided. An instruction issuing unit for issuing an instruction for enabling a storage area for temporarily storing data of the storage medium device for one unit; an instruction executing unit for executing an instruction for enabling the storage area; There is provided a disk array device provided with data restoration means for restoring lost data from a plurality of data storage medium devices even if data in an area is lost.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below.
In the disk array device shown in FIG. 3, 1 is a host computer, 2 is a disk array device, 3 is a disk array controller that controls each hard disk device, and 4 is a data input / output control and data between the host computer and the disk array controller. A host interface (HOST I / F) for temporarily storing data, a microprocessor (MPU) 5 for controlling the entire disk array controller, 6
Is a memory unit (MU) acting as a cache of the disk array controller, 7 is a hard disk channel (CH) for temporarily controlling data input / output between the disk array controller and the hard disk, and 8 is a disk unit in the disk array controller. A system bus, 9 is a hard disk device storing data, 10 is a write cache acting as a cache of the hard disk device, and 11 is a medium for storing data. Next, the operation will be described. Host computer 1
When the I / O request is issued from the HOST I / F 4, the HOST I / F 4 receives the command and data and stores it in the MU 6. MPU5 is C
A command is issued to the H7 to input / output data and parity of the hard disk device 9, and the CH 7 executes the instruction to input / output data and parity of the hard disk device 9.

As shown in FIG. 1, the disk array controller 3 counts the number of disk accesses to each hard disk drive 9 and holds the number as a table as shown in FIG. 2 (step 20). In step 21, one of the hard disk devices 9 having the largest number of disk accesses is determined from the table, and the write cache 10 is enabled from the MPU 5 of the disk array controller 3 for the determined one hard disk device 9.
(Write cache on) Issued instruction and received instruction 1
One hard disk drive 9 enables the write cache 10. When there is a disk access, the count value of the table is updated (step 23). At this time, if the number of disk accesses of the other hard disk devices 9 is larger (step 24), a command to change the hard disk device for enabling the write cache is issued from the disk array controller 3, and the hard disk device for enabling the write cache is issued. (Step 2
5). When the normal system stops, the disk array device 2 receives a shutdown command from the host computer 1 and writes the data in the write cache 10 to the medium 11 from the MPU 5 to the hard disk device 9 that has enabled the write cache 10. Issue an instruction. The hard disk drive writes the data stored in the write cache 10 to the medium 11 and the cache data is protected. However, when a power failure occurs, the power of the system is shut down without the disk array device 2 receiving the shutdown command, and the cache data of the hard disk device 9 is not written to the medium 11 because the shutdown process is not performed. When the power is turned on again, the data in the write cache 10 of the hard disk drive 9 has been lost. The write cache 10 of the hard disk drive 9 for which the write cache 10 was enabled is invalidated. Restore the lost write cache data using the RAID data restore function. During this restoration process, an access request from the server to the disk array device 2 can be processed using the remaining hard disk devices.

The disk array device 2 having the above configuration operates with the write cache 10 of the hard disk device 9 having a high disk access frequency enabled, so that the disk access can be speeded up.
Even if a power failure occurs and data is lost when the is enabled, the lost cache data can be restored by the RAID function of restoring data even if the data is lost. According to the present invention, when the disk array device has a configuration in which the number of times of disk access is uneven, the speed can be further increased.

[0009]

According to the present invention, the speed of the disk access can be increased by operating the storage area for temporarily storing data in the data storage medium device.

[Brief description of the drawings]

FIG. 1 is a diagram showing an operation of selecting a write cache with a high access frequency.

FIG. 2 is a table showing the number of accesses.

FIG. 3 is a schematic diagram of a disk array device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Host computer 2 ... Disk array device 3 ... Disk array controller 4 ... Host interface (HOST I / F) 5 ... Microprocessor (MPU) 6 ... Memory unit (MU) 7 ... Hard disk channel (CH) 8 ... System・ Bus 9 ... Hard disk drive 10 ... Write cache 11 ... Media

Claims (3)

[Claims] 1. A disk array device having a plurality of data storage medium devices for recording data, wherein the storage medium device temporarily stores data in a predetermined one of the plurality of data storage medium devices. Instruction issuing means for issuing an instruction to enable a storage area to be executed, instruction execution means to execute an instruction to enable the storage area, and a plurality of the data storage medium devices even if data in the storage area is lost A disk array device comprising a data restoring means for restoring lost data from said data. 2. The disk array device according to claim 1, further comprising: a determination unit that obtains statistics of disk accesses to each of the plurality of data storage media devices and determines one device having a high disk access frequency. The disk array device, wherein the instruction issuing means issues the instruction to one of the disks having a high frequency of disk access determined by the determining means. 3. A disk array device having a plurality of data storage medium devices for recording data, wherein the storage area of the storage medium device is effectively used for a predetermined one of the plurality of data storage medium devices. And recovering the lost data from the data in the plurality of data storage media devices even if the data in the storage area is lost.