JP2000357060A - Disk array device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-reliability disk array device capable of accelerating the data write speed of a device at low cost even in the case of for large capacity data at the time of recording data. SOLUTION: This device has dedicated magnetic disk devices 7f and 7g for temporarily holding data which are read into a cache memory 31 or data to be directly recorded in a logic unit 6 without being held in the cache memory 31 when recording data in the logic unit 6 and a controller 8 for controlling the dedicated magnetic disk devices 7f and 7g.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk array device, and more particularly, to recording data in a logical unit in accordance with a command from a higher-level device, without increasing the size of the device. The present invention relates to a disk array device capable of improving the data writing speed at a low price.

[0002]

2. Description of the Related Art In a conventional disk array device, there are a plurality of redundant systems for ensuring reliability when storing data.

[0003] Normally, RAID 1 (redundant array) is used as a method for ensuring data redundancy.
of inexpensive disks lev
el1), RAID2, RAID3, RAID4, RA
ID5 or RAID0 without data redundancy
There is a method used in a combination configuration of a plurality of RAID levels including the following.

[0004] Today, among these RAIDs, RAID5, which is resistant to random data access and has a high efficiency of use of a magnetic disk drive for recording data, is used.
Storage of data using a recording method using parity, which is called parity, has become the mainstream in the database market.

In a data storage method using parity, as in RAID 5, there is a method called RAID 3 which is used for accessing continuous data having a large access size, such as images and voices, but there is a part of the data storage method. In order to obtain reliability, there are many restrictions such as an influence on an OS (Operating System) such as a restriction on a data access size from a higher-level device and a requirement that a magnetic disk device to be used supports rotation synchronization. This is the actual situation.

Here, a conventional disk array device will be described with reference to the drawings.

FIG. 2 is a schematic block diagram showing a conventional disk array device 15. As shown in FIG.

Referring to FIG. 2, the disk array device 1
5 is an R including a plurality of magnetic disk devices 16a to 16e.
A logical unit 16 having an AID5 configuration, an array controller 13 for controlling recording and reproduction of data with respect to the logical unit 16 based on an instruction from the host device 11, and a cache memory for temporarily storing data under the control of the array controller 13. 131.

Next, the operation of the disk array device 15 configured as described above will be described.

When a data write command is issued from the host device 11, the array controller 13 temporarily stores the data in the cache memory 131 and then records it in the logical unit 16 designated by the host device 11, or writes the data to the cache memory 131. The data is passed through the inside of the array controller 13 without being stored, and is directly recorded on the logical unit 16.

Here, the logical unit 16 is a RAID 5
At the time of data writing, the magnetic disk devices 16a to 16e constituting the logical unit 16 are configured.
After the data and the parity signal already written in are written, the exclusive OR is calculated, and then the write operation is performed.

Therefore, during recording, there is a disadvantage that a delay occurs in the completion of data transfer from the host device 11 due to logical overhead.

To solve this problem, it is possible to increase the capacity of the cache memory 131.
The temporary storage of data to be stored in the magnetic disk devices 16a to 16e, which have been increasing in capacity, in the cache memory 131 composed of a semiconductor memory has a disadvantage that the cost of the device is increased.

There is a solution to reduce the logical overhead by adopting a method of recording data by data mirroring called RAID1, which is excellent in data write speed and data read speed.
Since the use efficiency of the mounted magnetic disk device is about half in the AID1 system, a large number of magnetic disk devices are required to handle a large amount of data. There are drawbacks such as accompanying.

[0015]

As described above,
In the conventional disk array system, in the RAID5 system, since there is an overhead of calculating an exclusive OR and writing after reproducing data and a parity signal which have already been written at the time of writing data, the higher order device is used. As a solution to reduce the logical overhead, a large-capacity cache memory is mounted on the array controller to reduce the data write speed from the host device. The measures to improve the performance require a large-scale cache memory capacity for performance improvement, and have a problem that the device price becomes extremely high. In addition, adopting the RAID1 method requires a large number of magnetic disk devices. Therefore, there is a problem that the price of the device is increased and the size of the device is increased.

An object of the present invention is to record data.
It is an object of the present invention to provide a highly reliable disk array device capable of improving the data write speed at a low price even for a large amount of data.

[0017]

According to the present invention, there is provided a disk array device comprising: a logical unit including a plurality of magnetic disk devices; an array controller for controlling recording and reproduction of data to and from the logical unit based on an instruction from a host device;
A cache memory composed of a semiconductor memory for temporarily storing data under the control of the array controller, and when recording data in the logical unit, the data read into the cache memory or directly stored in the cache memory without being stored in the cache memory. It is characterized by having a dedicated magnetic disk device for temporarily holding data recorded in the unit, and a controller for controlling the dedicated magnetic disk device.

The logical unit has a RAID 5 configuration.

The dedicated magnetic disk drive is characterized by comprising at least two units.

The dedicated magnetic disk drive is characterized in that data is mirrored in a RAID 1 configuration and always holds the same data.

The dedicated magnetic disk device is characterized in that it cannot be recognized as a logical unit by a host device and operates only as a disk cache.

The controller has a cache memory composed of a semiconductor memory, and controls the cache memory.

[0023]

Next, an embodiment of a disk array device according to the present invention will be described with reference to the drawings.

FIG. 1 is a schematic block diagram showing a disk array device 5 according to the present invention.

Referring to FIG. 1, the disk array device 5
Is a RAI including a plurality of magnetic disk devices 6a to 6e.
A logical unit 6 having a D5 configuration, an array controller 3 for controlling recording and reproduction of data with respect to the logical unit 6 based on an instruction from the host device 1, and an array controller 3
And a cache memory 31 for temporarily storing data under the control of the logical unit 6. When data is recorded in the logical unit 6, the data read into the cache memory 31 or directly in the logical unit 6 without being stored in the cache memory 31 are provided. The disk drive comprises dedicated magnetic disk devices 7f and 7g for temporarily storing data to be recorded in the hard disk drive, and a controller 8 for controlling the dedicated magnetic disk devices 7f and 7g.

Also, two dedicated magnetic disk units 7f,
7g is a RAID1 configuration, which performs data mirroring and always holds the same data.
, Cannot be recognized as a logical unit 6 and operates only as a disk cache.

Further, the controller 8 has a cache memory 81 composed of a semiconductor memory mounted thereon, and is configured to control the cache memory 81.

Next, the operation of the disk array device 5 configured as described above will be described.

When a data write command is issued from the host device 1, the controller 8 temporarily holds the data in the cache memory 81 and then holds the data in the dedicated magnetic disk devices 7f and 7g acting as disk caches. Alternatively, after passing through the inside of the controller 8 without being stored in the cache memory 81, control for directly storing the data in the dedicated magnetic disk devices 7 f and 7 g acting as a disk cache is performed.

Therefore, when data is recorded in the logical unit 6 composed of RAID5, before data is recorded in the designated logical unit 6 from the host device 1, the data is constructed by the RAID1 system excellent in recording speed. By temporarily storing data in the data holding area formed by the dedicated magnetic disk devices 7f and 7g, there is no delay in the completion of data transfer from the host device 1 due to the logical overhead at the time of RAID5 recording. Data transfer is completed at a speed that depends on RAID1, which is excellent in recording speed.

The data temporary holding area composed of the dedicated magnetic disk devices 7f and 7g having the RAID1 configuration has a sufficiently large capacity as compared with the cache memories 31 and 81 composed of semiconductor memories. The data transfer process from the higher-level device 1 to the logical unit 6 originally designated becomes possible in the background with a margin.

Further, the use of the dedicated magnetic disk devices 7f and 7g having the RAID1 configuration for the purpose of disk cache can prevent failure of the magnetic disk devices 6a to 6e constituting the logical unit 6 and stoppage of the disk array device 5. In the event of an accompanying failure, data can be retained,
It is possible to ensure sufficient reliability.

[0033]

As described above, the disk array device of the present invention transmits write command data from a higher-level device,
Before recording in a designated logical unit, the data is held in a disk cache area composed of a plurality of dedicated magnetic disk devices having a RAID1 configuration, so that it is possible to respond to a higher-level device without lowering performance when recording data. This has the effect.

The dedicated magnetic disk drive is used for data duplication, so it has excellent reliability and is inexpensive for recording large-capacity data unlike a memory composed of semiconductor elements. There is an effect that it becomes possible.

Further, since the dedicated magnetic disk device only functions as a disk cache for temporarily storing data, the RAID device designated by the higher-level device ultimately functions as a disk cache.
RA with high use efficiency of magnetic disk devices such as
Since the data is recorded in a logical unit having a redundant configuration different from ID1, it is possible to easily cope with data backup and the like.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing an embodiment of a disk array device according to the present invention.

FIG. 2 is a schematic block diagram showing an embodiment of a conventional disk array device.

[Explanation of symbols]

 1, 11 Host device 3, 13 Array controller 5, 15 Disk array device 6, 16 Logical unit 6a, 6b Magnetic disk device 6c, 6d Magnetic disk device 6e Magnetic disk device 7f, 7g Dedicated magnetic disk device 8 Controller 81 Cache memory 31 , 131 Cache memory 16a, 16b Magnetic disk drive 16c, 16d Magnetic disk drive 16e Magnetic disk drive

Claims (6)

[Claims] A logical unit composed of a plurality of magnetic disk devices; an array controller for controlling recording and reproduction of data with respect to the logical unit based on an instruction from a host device; and temporarily storing data under the control of the array controller. A cache memory comprising a semiconductor memory for holding, and when data is recorded in the logical unit, data read into the cache memory or data recorded directly in the logical unit without being held in the cache memory A disk array device comprising: a dedicated magnetic disk device for temporarily holding the disk drive; and a controller for controlling the dedicated magnetic disk device. 2. The disk array device according to claim 1, wherein said logical unit has a RAID5 configuration. 3. The disk array device according to claim 1, wherein the dedicated magnetic disk device comprises at least two units. 4. The dedicated magnetic disk drive according to claim 1, wherein
4. The disk array device according to claim 3, wherein the data is mirrored in one configuration, and always retains the same data. 5. The disk array device according to claim 1, wherein the dedicated magnetic disk device cannot be recognized as the logical unit by the host device, and operates only as a disk cache. 6. The disk array device according to claim 1, wherein the controller has a cache memory made of a semiconductor memory, and controls the cache memory.