JP2002132459A - Disk array device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disk array device that can increase the speed of storing/ reproducing on/from a disk and reduce the manufacturing cost. SOLUTION: This disk array device is equipped with several disk media and several magnetic heads for reading/writing predetermined data from/on the several disk media, and has a RAID control part that processes, in response to the several disk media, the predetermined data that are read from or written on the several disk media according to the instruction from an upper host, and a data assurance part that checks, according to the instruction of the RAID control part, whether the reading/writing of the predetermined data from/on the disk media is correct or not.

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 a disk array device that reads and writes data from and to a plurality of disk media in parallel, and divides and assembles the data to be read and written.

[0002]

2. Description of the Related Art Conventionally, a disk array device has a plurality of disk media and has a magnetic head corresponding to each disk medium. The divided data is stored in parallel in the plurality of disk media, or data that has been stored in a distributed manner is read from the plurality of disk media. At this time, the divided data is provided with redundancy so that data can be reconstructed even if one disk fails.

FIG. 3 shows a conventional disk array device 100. The disk array device 100 includes a host data control unit 102 for transferring data to and from a higher-level host 200, and a plurality of disk media 101 for reading and writing predetermined data in accordance with a command from the higher-level host 200. Then, a cache memory 103 to which predetermined data is input / output, a memory control unit 104 that controls the cache memory 103, and a RAID control unit 105 that processes data stored in the cache memory 103 corresponding to a plurality of disks 101 A disk data control unit 106 for transferring data between the cache memory 103 and the plurality of disks 101; and a data guarantee unit 107 for guaranteeing data read from and written to the disks 101.

Here, a conventional disk array device 10
The operation of writing data to the disk 101 at 0 will be described. First, the host data control unit 102 receives write data from the host 200 and stores the data in the cache memory 103. Then, RAID
The control unit 105 controls the RAI
The data in the memory is processed according to the state of D. For example, at the time of writing, data is divided.

[0005] Subsequently, the data assurance unit 107 has a trailer generation and check circuit 108 for generating a trailer including an error detection signal, and executes a trailer for data in the cache memory 103 in accordance with a request from the disk data control unit 106. Generated and added to the data,
Output to the disk data control unit 106. Then, the disk data control unit 106
The divided data is written to a plurality of disks 101.

At the time of data reading, an operation reverse to the above processing is performed. That is, first, the divided data is read from the disk 101 by the disk data control unit 106. Subsequently, the data assurance unit 107 checks the trailer of the data output from the disk data control unit 106, deletes the trailer, and deletes the trailer.
3 is stored. After that, the data divided by the RAID control unit 105 is assembled and transferred to the host 200 via the cache memory 103 and the host data control 102.

[0007]

However, the conventional disk array device has the following disadvantages. That is, to generate and check the trailer during data transfer between the cache memory and the disk,
A disadvantage arises in that the number of signals for transfer to the disk that starts simultaneously cannot be greater than the number of trailer generation and check circuits. Therefore, there is a problem that the data transfer speed at the time of storing and reproducing data on the disk medium cannot be improved.

On the other hand, when the number of interfaces for transferring data between the cache memory and the disk is increased in order to improve the data transfer, a trailer generation and check circuit is required corresponding to the increased number. Therefore, the number of trailer generation and check circuits is increased, which causes a problem that the apparatus is complicated and the manufacturing cost is increased.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is to improve the disadvantages of the prior art. In particular, the generation and checking of a trailer including an error detection signal are performed independently of the data transfer to the disk, and the number of disk transfers that can be started simultaneously It is an object of the present invention to provide a disk array device which can improve the storage and reproduction speed of a disk, reduce the number of trailer generation and check circuits, and reduce the manufacturing cost.

[0010]

Therefore, the present invention comprises a plurality of disk media, and a plurality of magnetic heads for reading and writing predetermined data on the plurality of disk media. And a RAID controller for processing predetermined data read / written from / to the disk medium in correspondence with a plurality of disk media. And
The configuration is such that a data assurance unit is provided for checking whether reading / writing of predetermined data to / from the disk medium is correct according to a command from the RAID control unit.

With this configuration, when data is written to the disk medium in accordance with a command from the host, the data to be written is written by the RAID control unit.
For example, it is processed so as to be divided according to the number of disk media. The processed data is written to a disk medium and then read. Then, the data assurance unit checks whether an error has occurred in the data due to writing and reading. At this time, the data assurance unit operates according to a command from the RAID control unit separately from the write and read operations. Therefore, by operating the data assurance unit, data reliability can be maintained, and data transfer with the disk can be executed independently regardless of the operation of the data assurance unit. The reproduction speed can be improved.

A cache memory for temporarily storing predetermined data; and a disk data control unit for controlling reading and writing of predetermined data to and from a plurality of disk media via the cache memory. Operate on predetermined data stored in the cache memory. This allows
For example, predetermined data from an upper host is stored in a cache memory, and RAID
Data processing is performed by the control unit, and data error checking is performed by the data guarantee unit. Since data read / write control to the disk medium is performed by the disk data control unit, data transfer with the disk can be performed independently of the data check operation by the data guarantee unit, and the data storage / reproduction speed Can be improved.

[0013] Further, the data assurance section has a code generation function of generating an error detection code corresponding to predetermined data, a code addition function of adding the error detection code to predetermined data written on a disk medium, It is desirable to have a code deletion function of deleting an error detection code from predetermined data read from the. Thus, at the time of data writing, an error detection code for detecting a data error is generated based on the data to be written by the code generation function, and the error detection code is added to predetermined data to be written by the code addition function. You. Then, at the time of data reading, an error of the data is checked, and the error detection code is deleted by the code deletion function. Therefore, since these functions operate via the cache memory, data transfer to and from the disk can be performed regardless of these operations, and the data storage / reproduction speed can be improved. Here, the error detection code is a code including, for example, a CRC code.

[0014] Further, the RAID control unit divides the predetermined data when the predetermined data is data to be written on the disk medium, and the predetermined data is data read from the disk medium. A data assembling function for assembling the predetermined data in the case,
The data assurance unit has a code generation function of generating an error detection code corresponding to the divided predetermined data, a code addition function of adding the error detection code to the divided predetermined data, and a data assembling function. A code deletion function for deleting an error detection code from the assembled data may be provided. Even in this case, the same operation as described above can be performed, and the above object can be achieved.

Further, a plurality of RAID control units may be provided. Even in this case, since a plurality of RAID control units share the data assurance unit, there is no need to increase the number of data assurance units, thereby improving the read / write processing speed, without complicating the structure, and reducing the manufacturing cost. Can be reduced.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a block diagram showing a configuration of a disk array device 1 according to the present invention. According to the disk array device 1 of the present invention, the divided data can be stored in a plurality of disk media 11 in parallel, or the data already distributed and stored from the plurality of disk media 11 can be read. it can. Data to be written and read is given redundancy, so that data can be reconstructed even if one disk 11 fails.

The disk array device 1 has a plurality of disk media 11 and a plurality of magnetic heads (not shown) for reading and writing predetermined data on the plurality of disk media 11.
A host data control unit 12 for performing data transfer with the host 2, a cache memory 13 for temporarily storing predetermined data, a memory control unit 14 for controlling input / output of the cache memory 13, 13 through a plurality of disk media 11
And a disk data control unit 1 for reading and writing predetermined data to and from a plurality of disk media 11 via the cache memory 13 in the same manner.
6 and a data guarantee unit 17 for checking whether reading / writing of predetermined data in the cache memory 13 to / from the disk medium 11 is correct according to a command from the RAID control unit 15.

Hereinafter, this will be described in detail.

The disk array device 1 is a storage device such as a hard disk which is built in or externally attached to the host 2 such as a personal computer. The disk array device 1 is connected to a host 2 via a host interface 18. The host interface 18 is, for example, a SCSI interface. The host interface 18 is connected to the host data control unit 12 of the disk array device 1.

The host data control unit 12 controls the host 2
In response to a command from the host, data is transferred to the host 2 such that data to be written to the disk medium 11 is received from the host 2 or data read from the disk medium 11 is transmitted to the host 2. Further, the host data control unit 12 is further connected to the cache memory 13. Specifically, the memory control unit 1 that controls input / output of the cache memory 13
4 is connected.

The cache memory 13 is a RAM having a predetermined capacity, and stores data received from the host 2,
Alternatively, data to be transmitted to the host 2 is temporarily held. Therefore, when the host 2 issues a write command to the disk medium 11, the host data control unit 12 receives the write data, and the host data control unit 12 stores the write data in the cache memory 13.
Output. Then, the output write data is stored in the cache memory 13 by the memory control unit 14. On the other hand, when a command to read from the disk medium 11 is issued from the host 2, the data read from the disk medium 11 is stored in the cache memory 13 by the memory control unit 14 as described later. Then, the stored read data is input to the host data control unit 12 by the memory control unit 14 and transmitted to the host 2 by the host data control unit 12.

The RAID control unit 15 processes write and read data temporarily stored in the cache memory 13 in correspondence with the plurality of disk media 11. For example, when data is stored in a plurality of disk devices in RAID-3, data is allocated and written together with the parity data, so that the write data is divided according to the number of disks 11 (data division function). Also, at the time of reading, the divided data as read data is assembled and the data is restored (data assembling function). After this division and assembling operation, the processed data is stored in the cache memory 13 again. However, the RAID control unit 15
Is not limited to the above operation.

The data assurance unit 17 includes a RAID control unit 15
It is checked whether or not the write and read data in the cache memory 13 are executed without any error according to the instruction. Specifically, the data holding unit 17 has a code generation function of generating an error detection code corresponding to the divided predetermined data, a code addition function of adding the error detection code to the divided predetermined data, A code removing function of removing an error detection code from the data assembled by the data assembling function.

The code generation function includes, for example, a CRC generation circuit 17b for generating a CRC code by cyclic error detection (CRC) and an additional data generation for generating management information (for example, a serial number and an address) of the divided data. Circuit 17
c. Here, the CRC generation circuit 17
"b" checks the CRC of the read data, and the additional data generation circuit 17c also checks the additional data of the read data. In addition, the sign addition function
It comprises a trailer adding circuit 17d for adding a trailer consisting of data of C code and additional data to the divided data. Here, the trailer adding circuit 17d creates an initial value of the additional data to be read from the information of the disk to be read, and also predicts the additional data to be read.
The code deletion function includes a trailer deletion circuit 17e for deleting a trailer of read data.

Further, the data holding section 17 includes a trailer detection circuit 17a and a trailer storage section 17f. The trailer detection circuit 17a detects a trailer including the CRC code of the read data and the additional data. Then, the detected trailer is the trailer deletion circuit 1.
7e, the trailer is deleted in the trailer storage unit 17
stored in f. That is, the trailer storage unit 17f
This is a memory having a predetermined capacity. Here, since the trailer stored in the trailer storage unit 17f is deleted after the trailer check is completed, the capacity of the trailer storage unit 17f is at least the trailer size (for example, 8 Bytes).
A capacity equal to e) is sufficient.

The disk data control section 16 writes and reads data to and from the disk 11. That is, the divided data is stored and reproduced on the disk 11 via the cache memory 13. At this time, the disk data control unit 16 and each disk 11
They are connected by a disk interface 19.

Next, the operation of this embodiment will be described with reference to FIG.
The operation of writing data to the disk and the operation of reading data from the disk 11 will be described separately.

In the case of a write operation, first, when a data write command is issued from the upper host 2, the write data from the upper host 2 is transferred to the host data controller 12.
Is received and stored in the cache memory 13. Subsequently, the RAID control unit 15
The data stored in the cache memory 13 is taken out from the cache memory 13 and the disk 1 on which the write data can be stored.
Data processing (eg, EXOR processing) is performed in accordance with the state 1 (RAID information), and then stored in the cache memory 13. Further, the RAID control unit 15 retrieves the processed data from the cache memory 13 again, and calculates the CRC of the write data using the CRC generation circuit 17b. Further, an initial value of the additional data is created from the information of the disk 11 to be written, and the additional data is calculated using the additional data generation circuit 17c. Then, the generated CRC code and the additional data are combined into a trailer, and the trailer is used as a trailer adding circuit 17d.
To convert the data by appending it to the write data,
It is stored in the cache memory 13. Further, the trailer addition position is determined by the trailer detection circuit 17a. Subsequently, the disk data control unit 16 retrieves the data to which the trailer has been added from the cache memory 13 and transfers the data to the disk 11 for storage.

On the other hand, the read operation is performed first on the disk 1
The data is read from 1 by a magnetic head (not shown), and the read data is received by the disk data control unit 16 and stored in the cache memory 13. Then RA
The ID control unit 15 retrieves the read data stored in the cache memory 13 from the cache memory 13, and the trailer detection circuit 17a detects the trailer portion of the read data. The detected trailer is
The trailer is deleted by the trailer deletion circuit 17e and stored in the trailer storage unit 17f. Further, in order to check whether or not there is an error in the read data, a CRC generation circuit 17b is used to calculate the CRC from the previously read data.
The code is generated and the additional data generation circuit
The initial value of the additional data is predicted and created from the information of the disk 11 to be read, and a trailer for checking is created from these. Then, by comparing the trailer for checking with the trailer deleted from the read data and stored in the trailer storage unit 17f, an error is detected by reading. Thereafter, the read data from which the trailer has been deleted is stored in the cache memory 13 again. Subsequently, the RAID control unit 15 further operates the disk 11 on which the read data has been stored.
Processing (EX) according to the status (RAID information)
OR processing). Then, the host data control unit 1
2 transfers the processed data from the cache memory 13 to the host 2.

By doing so, the disk 11
Since the trailer generation and check operations, which are error detection processes in reading and writing data from and to the disk, are performed on the memory, the transfer to the disk 11 and the trailer generation and check operations can be performed independently. Accordingly, a plurality of transfers with the disk 11 can be performed at the same time regardless of the trailer generation and check operations, and the speed of storage and reproduction on the disk 11 can be improved.

Further, since trailer addition and check operations are added as one operation of the RAID control unit 15,
Since a trailer generation and check circuit is not added in accordance with the number of transfer signals to and from the disk 11 started simultaneously, the number of circuits can be reduced and the manufacturing cost of the disk array device 1 can be reduced.

Next, another embodiment of the present invention will be described with reference to FIG. FIG. 2 is a block diagram showing a configuration of another embodiment of the present invention.

The other embodiment has substantially the same components as the disk array device 1 shown in FIG. The disk array device 2 illustrated in FIG. 2 further includes a plurality of RAID controllers 15A and 15B, and an arbiter 20 that performs a trailer generation by the RAID controllers 15A and 15B and a competition process of a check circuit use request. ing.

The operation of the other embodiment will be described. In the writing operation to the disk 11, first, the host data control unit 12 receives a plurality of read / write data from the host 2 and stores the data in the cache memory 13. Data processing and trailer generation are performed using the RAID control units 15A and 15B for each of the write data. Further, arbitration, which is a competition process for a request to use the trailer generation circuit 17, is performed, and the RAI to which use is granted is given.
The D control units 15A and 15B can use the trailer generation circuit 17. The disk data control unit 16 transmits the data on which the trailer has been generated and added to the disk 11.

In the read operation, first, the disk data control unit 16 controls the disk 1 in which the read data is stored.
1 and the data is taken out and stored in the cache memory 13. Subsequently, the RAID control units 15A and 15B check and delete the trailer, process the trailer, and reconstruct the read data. At the time of reading, arbitration is similarly performed to use the check circuit of the trailer. Then, the host data control unit 12 transmits the reconstructed read data to the host 2.

In this manner, a plurality of RAIs
Since the trailer generation and check circuit 17 is shared by the D control units 15A and 15B, the RAID control unit 15
Even if a plurality of A and 15B are mounted, it is possible to suppress an increase in the number of circuits 17 for executing trailer generation and checking, thereby increasing the reading / writing speed for the disk 11 and reducing the manufacturing cost of the disk array device 1. Can be. Further, in the present embodiment, a plurality of host interfaces 18 connecting the host 2 and the host data control unit 12 or a plurality of disk interfaces 19 connecting the disk data control unit 16 and the disk 11 may be connected. Also in this case, it is not necessary to increase the number of circuits 17 for generating a trailer or the like despite the addition of the RAID control units 15A and 15B, and the increase in the number of circuits inside the apparatus 1 can be suppressed.

[0038]

As described above, the disk array device of the present invention includes a plurality of disk media, a plurality of magnetic heads for reading and writing predetermined data from and to the plurality of disk media, A RAID control unit is provided for processing predetermined data read / written on a plurality of disk media in response to a plurality of disk media in accordance with a command, and reading / writing of predetermined data on a disk medium is correct in accordance with a command of the RAID control unit. When writing data to a disk medium in accordance with a command from the host, the data to be written is processed by the RAID control unit and the processed data is stored in the memory. The data assurance unit operates to add the assurance data and write and read the data to the disk medium. In this case, a check is performed by the data assurance unit according to a command from the RAID control unit to check whether an error has occurred in the data due to writing and reading. At this time, the data assurance unit performs Since the data assurance unit operates independently, data reliability can be maintained by operating the data assurance unit, and data can be transferred to and from the disk independently regardless of the operation of the data assurance unit. It has an unprecedented superior effect that the data storage / reproduction speed can be improved.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a configuration of another embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a conventional disk array device.

[Explanation of symbols]

 1 disk array device 2 host host 11 disk medium 12 host data control unit 13 cache memory 14 memory control unit 15, 15A, 15B RAID control unit 16 disk data control unit 17 data guarantee unit 18 host interface 19 disk interface 20 arbiter 17a trailer detection Circuit 17b CRC generation circuit 17c Additional data generation circuit 17d Trailer addition circuit 17e Trailer deletion circuit 17f Trailer storage unit

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G11B 20/10 G11B 20/10 A 20/18 512 20/18 512D 570 570Z 574 574E 576 576C F term (reference) 5B018 GA01 GA06 HA12 HA35 MA03 MA14 5B065 BA01 CA30 CE11 CH12 CH13 EA03 EA25 5D044 AB02 BC01 CC05 DE03 DE12 DE28 DE73 DE94 EF03 EF05 EF06 FG10 FG18 GK12 HL02

Claims (6)

[Claims] A plurality of disk media; a plurality of magnetic heads for reading / writing predetermined data from / to the plurality of disk media; and a predetermined magnetic disk which is read / written from / to the plurality of disk media by a command from a host. In a disk array device including a RAID control unit that processes data in accordance with the plurality of disk media, a command from the RAID control unit determines whether reading / writing of the predetermined data from / to the disk medium is correct. A disk array device comprising a data guarantee unit for checking. 2. A cache memory for temporarily storing the predetermined data, and a disk data control unit for controlling reading and writing of the predetermined data to and from the plurality of disk media via the cache memory; 2. The disk array device according to claim 1, wherein the data guarantee unit operates on the predetermined data stored in the cache memory. 3. A code generating function for generating an error detection code corresponding to the predetermined data, and a code adding function for adding the error detection code to the predetermined data written on the disk medium. 3. The disk array device according to claim 1, further comprising: a code deletion function for deleting the error detection code from the predetermined data read from the disk medium. 4. A data division function for dividing the predetermined data when the predetermined data is data to be written to the disk medium, wherein the RAID control section reads the predetermined data from the disk medium. A data assembling function for assembling the predetermined data when the data is divided data, wherein the data assurance unit generates an error detection code corresponding to the divided predetermined data; 2. The apparatus according to claim 1, further comprising: a code addition function of adding a detection code to the divided predetermined data; and a code deletion function of deleting an error detection code from the data assembled by the data assembling function. 3. The disk array device according to 1 or 2. 5. The disk array device according to claim 3, wherein the error detection code is a code including a CRC code. 6. The disk array device according to claim 1, wherein a plurality of said RAID control units are provided.