JPH11120089A - Parallel storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the rewriting efficiency of data and to speed up reading and writing by performing the rewriting only by the inversion of the recording data and parity data of bit parts where recording data and write data are different. SOLUTION: Data are read out of and written to parallel-connected magnetic disks Da to De under the control of a controller (disk array controller) 11, whose operation is controlled by a host computer 12. To rewrite recording data recorded in a specific area of some magnetic disk into different write data, the controller 11 reads only the recording data in the specific area out first and perform exclusive operation with the write data to be rewritten. Then different bits of the both are extracted and the recording data of the bit parts of the both and parity data corresponding to them are inverted to perform the rewriting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a parallel storage device in which a plurality of storage devices are connected in parallel, and reading and writing of data from and to these storage devices are controlled by a common control device.

[0002]

2. Description of the Related Art Conventionally, a plurality of storage devices such as magnetic disks are connected in parallel in order to increase the speed of reading or writing data or to improve the reliability, and a parallel storage system in which these storage devices are controlled by a common controller. The device has been put to practical use.

Here, a conventional parallel storage device will be described with reference to FIG. 3, taking a case where a magnetic disk is used as a storage device as an example. Symbols Da to De indicate magnetic disks connected in parallel. Each of the magnetic disks Da to De has a plurality of small-capacity areas for recording data such as recording data and parity data. For example, the magnetic disk Da has regions D0, D4, D8,..., And the magnetic disk Db has regions D1, D5, D9,. In FIG. 3, a small-capacity area for recording data is denoted by a symbol D.
, And the area where the recording data is recorded
, And the area where the parity data is recorded is represented by a symbol P.

The reading and writing of data from and to the magnetic disks Da to De are controlled by a disk array controller 31, and the operation of the disk array controller 31 is controlled by a host computer 32.

[0005] Here, in the parallel storage device having the above-described configuration, an operation for writing write data to the area D0 of the magnetic disk Da will be described. At this time, under the control of the disk array controller 31, the recording data (eg, d0 in FIG. 4) recorded in the area D0 of the magnetic disk Da and the area P0 of the magnetic disk De
0 (for example, p0 in FIG. 4)
) Is read. The read record data d0 and parity data p0 are exclusive ORed. Further, an exclusive OR of the operation result of the exclusive OR (for example, R1 in FIG. 4) and the write data to be written (for example, code d in FIG. 4) is obtained, and the result (for example, code R2 in FIG. 4) is newly obtained. As the parity data p, the area P of the magnetic disk De is used.
Written to 0. The write data d is written to the storage area D0 of the magnetic disk Da as recording data.

According to the method described above, the magnetic disk Da
The write data d is written to the area D0. The writing of write data to the other areas D4 and D8 of the magnetic disk Da or the other magnetic disks Db to De is performed in the same manner.

[0007]

In the conventional parallel storage device, when writing new write data to a predetermined area of the storage device, first, recording data recorded in the predetermined area and parity data corresponding to the recording data are written. Is being read. Then, an exclusive OR of the read recording data and the parity data is obtained, and thereafter, an exclusive OR of the operation result of the exclusive OR and the write data is obtained. Thereafter, the result obtained by the exclusive OR is written as parity data, and write data is written. As described above, the conventional parallel storage device requires many steps when writing write data,
This hinders speeding up of data reading and writing. Another problem is that the multi-access function cannot be used effectively.

An object of the present invention is to solve the above-mentioned disadvantages and to provide a parallel storage device in which data reading and writing are speeded up.

[0009]

SUMMARY OF THE INVENTION According to the present invention, there is provided a method for recording data in a predetermined area within a storage area for recording data.
A storage device, a second storage device in which parity data corresponding to the recording data is recorded in a predetermined area in a storage region for recording data, reading of data from the first storage device and the second storage device, and reading of the data. In a parallel storage device comprising a control device for controlling writing,
When rewriting the recording data recorded in the predetermined area of the first storage device to another write data,
Means for comparing the recording data with the write data and extracting a bit having a difference between the two, and rewriting the recording data of the first storage device and the parity data of the second storage device of the bit portion extracted by this means Means are provided.

[0010] The first storage device and the second storage device are magnetic disks.

According to the above configuration, when rewriting the recording data recorded in the predetermined area of the first storage device to another write data, the control device firstly stores only the recording data in the corresponding predetermined area. Is read and exclusive with the write data to be rewritten. Then, based on the result, bits different from each other are extracted, and the recording data of the bit portion where the two are different from each other and the corresponding parity data are inverted to perform rewriting. As described above, rewriting is performed only by inversion of the recording data and parity data of the bit portion where the recording data and the writing data are different.

Therefore, it becomes unnecessary to read the parity data corresponding to the recording data to be rewritten.
Also, the number of steps for rewriting is reduced. As a result, the generation of the parity data is simplified, the access time to the storage device is shortened, the data rewriting efficiency is improved, and the data reading and writing speed is increased. In addition, since the number of steps is reduced, reading and rewriting operations of other storage devices can be performed using the time, and a parallel storage device that effectively utilizes the multi-access function can be realized.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. 1 taking a case where a magnetic disk is used as a storage device as an example. Symbols Da to De are magnetic disks for recording data such as recording data and parity data. Each of the magnetic disks Da to De has, for example, a plurality of small-capacity areas for recording data. In the case of the magnetic disk Da, areas D0, D4,
, And the magnetic disk Db has data recording areas D1, D5, D9,. In FIG. 3, a small-capacity area in which data is recorded is indicated by a code D or P, an area in which record data is recorded is indicated by a code D, and an area in which parity data is recorded is indicated by a code P.

Here, the magnetic disks Da to De are used here.
The parity data, for example, p0, p1, p2,...
The area P0, the area P1 of the magnetic disk Dd, the area P2 of the magnetic disk Dc, etc. are sequentially recorded on different magnetic disks, and control is performed so that recording is not concentrated on a specific magnetic disk. The parity data is usually set so that the sum of the code "1" of the recording data and parity data recorded on each of the magnetic disks Da to De is an even number or an odd number for each bit.

The magnetic disks Da connected in parallel
The reading and writing of data with respect to .about.De are controlled by a control device, for example, a disk array controller 11, and the operation of the disk array controller 11 is controlled by a host computer 12.

The operation for writing write data to the area D0 of the magnetic disk Da will now be described. First, the disk array controller 11 reads the recording data (for example, code d0 in FIG. 2) written in the area D0 of the magnetic disk Da. Then, the read recording data d0 and the write data (for example, the symbol d in FIG. 2) are mutually exclusive. From the result (for example, symbol R1 in FIG. 2),
Bits that need to be rewritten in the area D0 of the magnetic disk Da (for example, a portion surrounded by a frame in FIG. 2) are extracted. Then, by utilizing the detection result, of the recording data d0 written in the area D0 of the magnetic disk Da and the parity data (for example, the code p0 in FIG. 2) recorded in the area P0 of the disk area De, The bit portion that needs to be rewritten (for example, the portion surrounded by the frame in FIG. 2) is inverted.
At this time, the recording data d is recorded in the area D0 of the magnetic disk Da, and the parity data p is recorded in the area P0 of the disk area De.

According to the above configuration, the write data d to be rewritten is compared with the write data d to extract the bits that need to be rewritten. Then, the recording data d0 and the parity data p0 of the bit portion requiring rewriting are inverted. In this case, it is not necessary to read the parity data p0 corresponding to the recording data d0. Also,
The total number of steps is also reduced. For this reason, the control time of the disk array controller required for rewriting the write data to one area is shortened, and the control time of the disk array controller has a margin. Therefore, the disk array controller can control the other magnetic disks Db to Dd by utilizing such idle time. For example, at the time when the area D0 of the magnetic disk Da is rewritten to the write data d, the areas D5, D6 or D9 of the magnetic disks Db, Dc and Dd having the areas D1, D2 and D3 which are not related to the rewrite of the write data d. D10 can be read and written, and the multi-access function can be used effectively.

In the above embodiment, the operation in the case where write data is written to the area D0 of the magnetic disk Da has been described. However, the other areas D4 and D8 of the magnetic disk Da or the other magnetic disks Db to Db
Writing write data to e is performed in a similar manner.

The above embodiment has been described in connection with the case where a magnetic disk is used as a storage device. However, the present invention is also applicable to storage devices other than magnetic disks.

[0020]

According to the present invention, it is possible to realize a parallel storage device in which reading and writing of data are speeded up.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention.

FIG. 2 is a diagram illustrating the operation of the present invention.

FIG. 3 is a circuit configuration diagram showing a conventional example.

FIG. 4 is a diagram illustrating the operation of a conventional example.

[Explanation of symbols]

 11 Control device 12 Host computer Da to De Magnetic disk D0 to D11 Area where recorded data is recorded P0 to P2 Area where parity data is recorded

Claims (2)

[Claims] 1. A first storage device in which recording data is recorded in a predetermined area in a storage area for recording data, and a first storage device in which parity data corresponding to the recording data is recorded in a predetermined area in a storage area for recording data. 2 storage device, and a control device that controls reading and writing of data to and from the first storage device and the second storage device, the storage device being stored in the predetermined area of the first storage device. Means for comparing the write data with the write data when rewriting the write data to another write data, and extracting a bit having a difference between the write data and the write data; Means for rewriting recording data of one storage device and parity data of the second storage device. 2. The parallel storage device according to claim 1, wherein the first storage device and the second storage device are magnetic disks.