JPH04259025A - Disk array controller - Google Patents

Abstract

PURPOSE:To write the data including the check data at a high speed by generating effectively the check data on the write data to be written into the disk drives forming a disk array. CONSTITUTION:The write data transferred from a host computer 1 are stored in the buffer memories BM0-BM2 for each disk drive. A check data generating circuit 6 generates the check data based on the write data written in the memories BM0-BM2. Then the check data are sent to a check disk drive D3, and the write data are transferred to the corresponding disk drives D0-D2 respectively.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk array control device having a function of checking data recorded on a plurality of disk drives.

0002

2. Description of the Related Art Conventionally, a disk array device includes a plurality of disk drives D0 to D3 (four in this example) and a shared controller 2, as shown in FIG. The controller 2 controls each disk drive D0 to D3.
, and constitutes an interface between each disk drive D0 to D3 and the host computer.

By the way, a normal disk array device is
One of the plurality of disk drives D0 to D3 is used as a check disk drive D3, and has an error check function (ECC function) using check data such as parity data or checksum data. The controller 2 generates check data using data such as user data other than the check data CD.

As shown in FIG. 6, logical sector addresses 0-11 are set for each recording medium of each data disk drive D0-D2 in addition to physical sectors 0-3. The controller 2 has each disk drive D0
Check data corresponding to each piece of data in the same physical sector written to ~D2 is generated and stored in the same physical sector of the check disk drive D3. Specifically, for example, calculate the sum of each data (3 bytes) at the same byte position of each disk drive D0 to D2 in physical sector 0,
This checksum data (CD012) is stored as check data CD in the same byte position in the same physical sector of drive D3. By using this check data CD, when one of the disk drives D0 to D2 fails, it is possible to restore the data recorded in the failed drive.

By the way, each time data is transferred from the host computer during a write operation, the controller 2
The check data CD as described above is generated and stored in the buffer memory. In this case, when new data is transferred from the host computer, it is necessary to update the check data CD. Therefore, the controller 2 reads the previous check data CD from the buffer memory, updates the previous check data CD based on the new data, and
Store it in the buffer memory again.

[0006]

In the conventional system, check data CD is generated during a data write operation and stored in a buffer memory. When updating the check data CD, it is necessary to access the buffer memory twice. As a result, there is a problem in that the speed of data writing to the disk drive decreases.

An object of the present invention is to provide a disk array control device that efficiently generates write data check data for each disk drive that constitutes a disk array, thereby realizing faster data writing operations. There is a particular thing.

[0008]

[Means for Solving the Problems] The present invention provides a disk array control device that controls each of a check disk drive that stores check data and a plurality of disk drives that stores write data such as user data. Buffer memory means for storing each write data to be transferred for each disk drive, check data generation means for generating check data based on each write data stored in the buffer memory means, and check data generated by the check data generation means. The apparatus includes data transfer means for transferring check data to a check disk drive and transferring each write data stored in a buffer memory means to each corresponding disk drive.

[0009]

According to the present invention, write data transferred from a host computer is stored in buffer memory means for each of a plurality of disk drives. The check data generation means generates check data based on each write data stored in the buffer memory means. This check data is transferred to the check disk drive. Further, each write data is transferred to each corresponding disk drive. Thereby, when write data for each disk drive is transferred from the host computer, check data can be generated based on each write data.

0010

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

FIG. 1 is a block diagram showing the main parts of a disk array system according to an embodiment of the present invention. This system includes a host computer 1, a controller 12, and a plurality of disk drives (four in this case) D0 to D.
Consists of 3. The disk drives D0 to D3 include a check disk drive D3 for storing check data CD and disk drives D0 to D2 for storing data such as user data other than check data.

The controller 12 has a host bus 3 and a disk bus 4, and is connected to the host computer 1 through the host bus 3, and to each of the disk drives D0 to D3 through the disk bus 4. The controller 12 has a plurality of transceivers (data transmitting/receiving devices) 5a to 5c connected to the host bus 3, and executes data transfer with the host computer 1. The controller 12 has a plurality of buffer memories BM0-BM2 corresponding to each disk drive D0-D2, respectively. Each buffer memory BM0 to BM2 is connected to each transceiver 5.
Write data transferred from the host computer 1 through a to 5c is stored.

Furthermore, the controller 12 has a check data generation circuit 6. The check data generation circuit 6 is
It has a function of generating check data based on each write data stored in each buffer memory BM0 to BM2 and transferring it to the check disk drive D3 via the disk bus 4. On the other hand, the check data generation circuit 6 functions simply as a multiplexer, and each buffer memory B
Each write data stored in M0 to BM2 is transferred to each corresponding disk drive D0 to D2.

The controller 12 also includes a read transceiver 7 for transferring read data from each disk drive D0 to D3 to the host computer 1, a CPU 8 for controlling the entire controller 12, a disk interface 9, a host interface 10, and It is equipped with a memory 11. Disk interface 9
is an interface with each of the disk drives D0 to D3, and is a circuit for transmitting commands and receiving status and the like. The host interface 10 is
It is an interface with the host computer 1, and is a circuit for receiving commands and the like from the host computer 1 and transmitting status and the like. Memory 11 is RA
It consists of M and ROM, and stores programs for the CPU 8 and various control data.

Next, the operation of this embodiment will be explained.

First, when the host computer 1 simultaneously writes data to consecutive data sectors (logical sector addresses) of three disk drives D0 to D2, it writes data to each disk drive D0 to D2. Buffer memories BM0 to BM2 are allocated. That is, Figure 2
As shown in , when the write data of each data sector is simultaneously transferred from the host computer 1, each buffer memory BM0 to BM0 corresponding to each disk drive D0 to D2 is transferred.
Stored in BM2. That is, the write data of the disk drive D0 is stored in the buffer memory BM0, the write data of the drive D1 is stored in the buffer memory BM1, and the write data of the drive D2 is stored in the buffer memory BM2.

During a data write operation, the check data generation circuit 6 functions simply as a multiplexer and transfers each write data stored in each buffer memory BM0 to BM2 to each disk drive D0 to D2.

Next, the check data generation circuit 6 reads each write data corresponding to a predetermined check data group from each buffer memory BM0 to BM2, and executes a process of generating check data. During check data generation processing, each transceiver 5a to 5c is all turned off.

In this embodiment, the check data group is a write data group belonging to a data sector (logical sector) corresponding to the same physical sector of each disk drive D0 to D2. That is, a check operation (for example, a parity operation) is performed based on each write data (logical sectors 0 to 2) corresponding to physical sector 0, and the check data CD0
Generate 12. Similarly, as shown in FIG.
901 is generated. Each generated check data is written to the same physical sector of the check disk drive D3 corresponding to the group.

Next, a case will be described in which a data write operation (data update) is executed only in logical sector n, as shown in FIG. 3, among the data sectors belonging to the check data group. Here, host computer 1
For example, when write data for one sector is transferred to the disk drive D1, the transferred update data is stored in the buffer memory BM1. At this time, each disk drive D0, D2 has not executed a write command, so each remaining data sector (n
-1, n+1) are read from the corresponding disk drives D0, D2. That is, each data read from each disk drive D0, D2 is sent to each buffer memory B through the reading transceiver 7.
Stored in M0 to BM2.

After this, the check data generation circuit 6
Each write data including update data of logical sector n is read from each buffer memory BM0 to BM2, and a process of generating check data CD is executed. This check data CD is written to the same physical sector (for example, sector 0) of the check disk drive D3 corresponding to the group and updated.

Further, as shown in FIG. 4, for example, when data in logical sector n of disk drive D1 is updated, old data n of this logical sector n is read from disk drive D1 and stored in buffer memory BM0. . Furthermore, the old check data CD corresponding to the group of logical sectors n is read from the check disk drive D3 and stored in the buffer memory BM2. The check data generation circuit 6 executes a process of generating new check data CD based on the update data (new data n), old data n, and old check data CD stored in the buffer memory BM1. As a result, the new check data CD is written and updated in the same physical sector (for example, sector 0) of the check disk drive D3 corresponding to the group, as described above.

Furthermore, as shown in FIG. 5, among the data sectors belonging to the group, for example, disk drive D1
, D2, data corresponding to the remaining data sector n-1 is read from the corresponding disk drive D0. This data is stored in buffer memory BM0.

The check data generation circuit 6 reads old data in logical sector n-1 and updated data in logical sectors n and n+1 from each buffer memory BM0 to BM2.
Execute processing to generate new check data CD. The new check data CD is stored in the same physical sector (for example, sector 0) of the check disk drive D3 corresponding to the group.
) and will be updated.

In this way, each buffer memory BM0 to BM2 stores each write data of each disk drive belonging to the check data group (same logical sector).
is provided, and check data is generated for each group at the time of data writing.

[0026] Therefore, the following effects can be obtained. First, even if an error occurs in the write data while the write data is being transferred to each disk drive, the write data of only the sector where the error occurred is read from each buffer memory BM0 to BM2 and transferred again. (See Figure 2).

Second, when some data in a data sector belonging to a group is updated, the check data corresponding to the group is updated by reading each data in the remaining data sectors to the corresponding buffer memory. Updates can be made (see Figures 3 and 5).

Third, when some data in a data sector belonging to a group is updated, the old data and old check data are stored in the buffer memory, the write data is updated, and the updated data and old data are and the check data can be updated based on the old check data (see FIG. 4).

[0029]

As described in detail above, according to the present invention, by providing each buffer memory for each disk drive to store each write data belonging to a check data group, check data can be generated during a data write operation. and updates can be performed efficiently. therefore,
As a result, it is possible to speed up the write operation of data including check data.

[Brief explanation of the drawing]

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

FIG. 2 is a conceptual diagram for explaining the operation of the embodiment.

FIG. 3 is a conceptual diagram for explaining the operation of the embodiment.

FIG. 4 is a conceptual diagram for explaining the operation of the embodiment.

FIG. 5 is a conceptual diagram for explaining the operation of the embodiment.

FIG. 6 is a block diagram for explaining a conventional disk array device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1...Host computer, 6...Check data generation circuit, 12...Controller, BM0-BM2...Buffer memory, D0-D3...Disk drive.

Claims (1)

[Claims] 1. A disk array control device that controls a plurality of disk drives and controls data transfer between each disk drive and a host computer, comprising:
A check disk drive for storing check data of each write data recorded on each disk drive among the plurality of disk drives, and a check disk drive for storing each write data transferred from the host computer for each disk drive. a buffer memory means for generating the check data based on the write data stored in the buffer memory means; a check data generating means for generating the check data based on the write data stored in the buffer memory means; and data transfer means for transferring each of the write data stored in the buffer memory means to each corresponding disk drive.