JPH05334010A - Disk array device - Google Patents

Abstract

PURPOSE:To eliminate a labor of disk medium management by providing a discrimination information writing and detecting circuit, which indicates the disk position for write, and a connection switching circuit. CONSTITUTION:First, second, and third data strings are read out from optical disk drives 12, 11, and 13 by disk drive interface circuits 9, 8, and 10, respectively, and are inputted to a connection switching circuit 4. Simultaneously, discrimination information recorded at the time of write are read out from optical disk drives 11, 12, and 13 by discrimination information writing and detecting circuits 5, 6, and 7, respectively, and are inputted to the connection switching circuit 4 to switch the connection.

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 for writing and reading computer data, digital audio data, digital video data and the like at high speed and with high reliability as an external storage device for computers, digital audio and video equipment. It is a thing.

[0002]

2. Description of the Related Art In recent years, a central processing unit (C
The processing speed of the (PU) has been remarkably improved, and accordingly, a high-speed external storage device such as a disk device which is a peripheral device has been required. Also, in the fields of audio and video, digitization of processing and recording / reproduction is rapidly progressing, and a disk device capable of inputting / outputting a large amount of data at high speed is required as a storage device. As a disk device suitable for such applications,
2. Description of the Related Art Conventionally, there has been known a disk array device technology that realizes an equivalently high-speed and large-capacity disk device by operating a plurality of small disk drives in parallel. In particular, a paper by Patterson et al. "" RAID, an example of a redundant array using an inexpensive disk: A Case
for Redundant Arrays of I
nexpensive Disks (RAID) ″ AC
Proceedings of M SIGMOD International Conference (1988)
p. 109-116 ”, the proposed RAI
The D technology is currently the most popular technology for realizing the disk array device as described above.

A conventional disk array device as described above will be described below with reference to the drawings.

FIG. 5 is a block diagram showing an example of the configuration of a conventional disk array device based on the RAID technique using three hard disk drives as disk memories. In the figure, 41 is a system control circuit, 42 is a host interface circuit, 43 is a disk array control circuit connected to the host interface circuit 42, 44,
45 and 46 are disk drive interface circuits connected to the disk array control circuit 43, and 47, 48 and 49 are disk drive interface circuits 44 and 4.
5 and 46 are hard disk drives.

The operation of the conventional disk array device having such a configuration will be described. FIG. 6 is a diagram schematically showing a data string stored in each hard disk drive when a data string to be recorded is given to the disk array device.

In FIG. 5 and FIG. 6, first, the data string to be recorded is transferred from the host CPU such as the CPU to the disk array control circuit 4 by the host interface circuit 42.
Input to 3. The disk array control circuit 43 is shown in FIG.
As shown in FIG. 3, the data string is divided into two (51a, 51b), and after adding parity which is redundant data for detecting an error, three data strings 51a, 51b, 51c are added.
Parallelize to. For the three parallel data strings 51, the first data string 51a passes through the disk drive interface circuit 44 and the hard disk drive 47a.
Then, the second data string 51b is passed through the disk drive interface circuit 45 to the hard disk drive 48,
The third data string 51c is written and recorded in the hard disk drive 49 via the disk drive interface circuit 46. When reading,
The first data string is from the hard disk drive 47 to the disk drive interface circuit 44, the second data string is from the hard disk drive 48 to the disk drive interface circuit 45, and the third data string is from the hard disk drive 49 to the disk drive interface circuit 46. , And the disk array control circuit 43 performs error protection using parity, and at the same time, the data is serialized and sent to the CPU or the like via the host interface circuit 42. The system control circuit 41 is for controlling a series of operations of each circuit.

As described above, the disk array device using RAID technology realizes high speed, large capacity and high reliability by operating a plurality of disk drives in parallel while performing error protection by parity. is there.

[0008]

However, in the above-mentioned conventional disk array apparatus, if the disk drive is a fixed disk whose disk medium is not replaceable, no problem will occur, but it has been widely used in recent years. If the disk medium that has come to be used is a replaceable disk drive, for example, an optical disk drive or a removable disk, a problem occurs if the disk medium insertion order is different between writing and reading.
That is, the disk medium inserted into the first disk drive during writing is always the first disk drive during reading, and the disk medium inserted into the second disk drive during writing is always the second disk drive during reading. It is troublesome to manage the disk medium because the disk medium inserted into the third disk drive at the time of writing to the disk drive cannot be expected to operate normally unless it is inserted into the third disk drive at the time of reading. Had a problem.

The present invention has been made in view of the above-mentioned problems of the conventional disk array device, and does not cause a problem even if the disk medium is inserted into an arbitrary drive both at the time of writing and at the time of reading. It is an object of the present invention to provide an excellent disk array device that does not require troublesome management.

[0010]

In order to achieve the above object, the present invention is provided with an identification information writing and detecting circuit for indicating a disk position at the time of writing and a connection switching circuit, or a polynomial arithmetic circuit for calculating position information by parity. And a data string rearrangement circuit for rearranging the data strings based on the calculation result.

[0011]

With the above configuration, the position of the disk medium at the time of writing is recorded on the disk medium as identification information,
Even if the disk medium is inserted at a different position during reading, the connection can be switched based on the detected identification information, or the parity including the disk medium position information during writing can be used to read data during reading. Since the columns can be rearranged, the position of the disk can be corrected equivalently, and no problems will occur even if the disk medium is inserted into any drive during both writing and reading. Therefore, there is no need to manage the disk medium. It is possible to realize an excellent disk array device that does not have such a problem.

[0012]

【Example】

(Embodiment 1) Hereinafter, a disk array device according to a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a disk array device according to the first embodiment of the present invention. In the figure, 1 is a system control circuit, 2 is a host interface circuit, 3 is a disk array control circuit, 4 is a connection switching circuit, 5, 6 and 7 are identification information writing and detecting circuits, and 8 and 9 are disk drive interfaces. The circuits, 11, 12 and 13 are optical disk drives.

The operation of the disk array device according to the first embodiment of the present invention constructed as above will be described. First, the data string to be recorded is input to the disk array control circuit 3 from the CPU, which is the host, by the host interface circuit 2 as in the conventional disk array device. The disk array control circuit 3 adds parity, which is redundant data for detecting an error, and then parallelizes it into three data strings. The three parallel data strings pass through the connection switching circuit 4 as they are, and the first data string is the disk drive interface circuit 8
To the disk medium inserted into the optical disk drive 11, the second data string to the disk medium inserted to the optical disk drive 12 via the disk drive interface circuit 9, and the third data string to the disk drive interface circuit 10. The data is written on the disk medium inserted into the optical disk drive 13 via the disk. At that time, the identification information indicating that the first data string has been written by the identification information writing / detecting circuit 5 is simultaneously recorded on the disc medium inserted into the optical disc drive 11.

Similarly, identification information indicating that the second data string has been written by the identification information writing / detecting circuit 6 on the disc medium inserted in the optical disc drive 12 is recorded on the disc medium inserted in the optical disc drive 13. By the identification information writing and detecting circuit 7
The identification information indicating that the data string has been written is recorded. Next, at the time of reading, at the time of writing, the first data string inserted into the optical disk drive 11 or the written disk medium is inserted into the optical disk drive 12, and at the time of writing, inserted into the optical disk drive 12 and the second data string is written. The operation at the time of reading will be described by taking as an example the case where another disk medium is inserted into the optical disk drive 11.

First, the second data string is sent from the optical disk drive 11 to the disk drive interface circuit 8, the first data string is sent from the optical disk drive 12 to the disk drive interface circuit 9, and the third data string is sent from the optical disk drive 13 to the disk. It is read by the drive interface circuit 10 and input to the connection switching circuit 4.

At the same time, the identification information recorded during writing is sent from the optical disc drive 11 by the identification information writing and detecting circuit 5, from the optical disc drive 12 by the identification information writing and detecting circuit 6, and from the optical disc drive 13 by the identification information writing and detecting circuit 7. , Respectively, and are similarly input to the connection switching circuit 4. FIG. 2 is a block diagram showing the connection switching circuit 4 in FIG. 1 in more detail. As shown in the figure, the connection switching circuit 4 includes three sets of 3 controlled by the identification information.
Since the identification information output from the identification information writing / detecting circuit 5 indicates the second data string, the output from the disk drive interface circuit 8 is the second one of the disk array control circuit 3.
Since the identification information output from the identification information writing / detecting circuit 6 indicates the first data row at the data row input of, the output from the disk drive interface circuit 9 is the first data row of the disk array control circuit 3. At the input, the identification information output from the identification information writing / detecting circuit 7 indicates the third data string, so the output from the disk drive interface circuit 10 is input to the third data string input to the disk array control circuit 3. Connected respectively.

By the above operation, the three read data strings become the same as those at the time of writing, and the disk array control circuit 3 performs the error protection using the parity and at the same time the data is serialized to the host interface circuit 2. The data sequence recorded in the CPU is read out by the CPU or the like.

As described above, according to the present embodiment, by adding some processing such as identification information processing and data path connection switching to the conventional RAID technology, the writing and reading speed is not impaired, and the writing Thus, it is possible to realize a disk array device that does not cause a problem even when the disk medium is inserted into an arbitrary drive at the time of reading.

(Embodiment 2) Next, a second embodiment of the present invention will be described with reference to the drawings.

FIG. 3 is a block diagram showing the configuration of a disk array device according to the second embodiment of the present invention. In the figure, 21 is a system control circuit, 22 is a host interface circuit, 23 is a data string rearrangement circuit, 24 is a polynomial arithmetic circuit, 25 is a disk array control circuit, 26, 27 and 28 are disk drive interface circuits, 29,
Reference numerals 30 and 31 are optical disk drives.

The operation of the disk array device according to the second embodiment of the present invention constructed as above will be described. The writing of the data string to be recorded is almost the same as that of the conventional disk array device shown in FIG. 6, and the data string to be recorded is transferred from the CPU as the host to the data string rearrangement circuit 2 by the host interface circuit 22.
After passing through 3, the data is input to the disk array control circuit 25.

In the disk array device of this embodiment, when parity is added in the disk array control circuit 25, on a finite field used in Reed-Solomon code which is an error correction code of a compact disk or a digital audio tape recorder. Take advantage of the properties of polynomials. For example, when adding the parity P1 for the data A and data B shown in FIG.

[0024]

[Equation 1]

Arithmetic processing is performed in the polynomial arithmetic circuit 24 so that the value satisfies the above condition. Note that all calculations at this time are defined on a finite field. After adding parity in this way, it is parallelized into three data strings,
The first data string goes to the optical disk drive 29 via the disk drive interface circuit 26, the second data string goes to the optical disk drive 30 via the disk drive interface circuit 27, and the third data string goes to the disk drive interface circuit 28. The data is recorded in the hard disk drive 31.

Next, at the time of reading, at the time of writing, the disk medium inserted into the optical disk drive 29 and having the first data string written therein is inserted into the optical disk drive 30, and at the time of writing the second data string inserted into the optical disk drive 30. The operation at the time of reading will be described with reference to the case where the disk medium in which is written is inserted into the optical disk drive 29.

FIG. 4 is a schematic diagram showing the operation of the disk array device according to the second embodiment of the present invention.

In the figure, first, the second data string is from the optical disk drive 29 to the disk drive interface circuit 26, the first data string is from the optical disk drive 30 to the disk drive interface circuit 27, and the third data string is the optical disk drive. The disk drive interface circuit 28 reads the data from 31 and inputs the data to the disk array control circuit 25, and the disk array control circuit 25 serializes the data while maintaining the parity. The serialized data string is divided into three and output to the polynomial arithmetic circuit 24 and the data string rearrangement circuit 23. In the polynomial arithmetic circuit 24, the three input data are converted into polynomial

[0029]

[Equation 2]

All combinations that apply to the three variables x0, x1, and x2 in this case, in this case, six combinations are calculated, and a combination in which the value of the polynomial is zero is found. As a property of a polynomial in a finite field, the value becomes 0. In the example of the description at the time of writing, the data A is applied to x0, the data B is applied to x1, and the parity P1 is applied to x2. 1) Only when they are the same, it is possible to know the data arrangement at the time of writing, no matter how the order of the serialized data strings changes.

The polynomial arithmetic circuit 24 outputs this arrangement information to the data string rearrangement circuit 23, and the data string rearrangement circuit 2
3 rearranges the data string serialized by the disk array control circuit 25 into a correct data string, and finally the data string recorded by the host interface circuit 22 is C.
It is read by the PU or the like.

As described above, according to this embodiment, the disk medium can be inserted into an arbitrary drive at the time of writing and reading by a software method without using special auxiliary information such as identification information. A disk array device can be realized.

[0033]

As described above, the present invention is provided with an identification information writing and detecting circuit for indicating a disk position at the time of writing and a connection switching circuit, or a polynomial arithmetic circuit for calculating positional information by parity and its arithmetic result. By providing a data string rearrangement circuit that rearranges data strings based on the above, even if the disk medium is inserted into different drives at the time of writing and at the time of reading, no malfunction occurs in operation, and therefore, it is completely necessary to manage the disk medium. It is possible to realize an excellent disk array device that does not take time and effort.

Although the optical disk has been described as an example of the disk memory here, it goes without saying that the same effect can be obtained by using another disk memory whose medium can be exchanged, for example, a removable disk.

In addition to the disk memory, the technique of the present invention can be applied to, for example, a tape device or a semiconductor memory device.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing a detailed configuration of a connection switching circuit in FIG.

FIG. 3 is a block diagram showing the configuration of a disk array device according to a second embodiment of the present invention.

FIG. 4 is a schematic diagram showing an operation of a disk array device according to a second embodiment of the present invention.

FIG. 5 is a block diagram showing an example of the configuration of a conventional disk array device.

FIG. 6 is a schematic diagram showing the operation of a conventional disk array device.

[Explanation of symbols]

1, 21 System control circuit 2, 22 Host interface circuit 3, 25 Disk array control circuit 4 Connection switching circuit 5, 6, 7 Identification information writing and detection circuit 8, 9, 10, 26, 27, 28 Disk drive interface circuit 11 , 12, 13, 29, 30, 31 Optical disk drive 23 Data string rearrangement circuit 24 Polynomial arithmetic circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location G11B 20/10 D 7923-5D 20/12 7033-5D

Claims (2)

[Claims] 1. A plurality of disk memories having exchangeable disk media, a plurality of disk drive interface circuits respectively connected to the plurality of disk memories, and a plurality of disk drives interface circuits respectively connected to the plurality of disk drive interface circuits. Identification information writing and detecting means, a plurality of disk drive interface circuits, a connection switching circuit connected to the plurality of identification information writing and detecting means, a disk array control circuit connected to the connection switching circuit, and the disk A disk array device comprising a host interface circuit connected to an array control circuit. 2. A plurality of disk memories having exchangeable disk media, a plurality of disk drive interface circuits respectively connected to the plurality of disk memories, and a disk array control circuit connected to the plurality of disk drive interface circuits. A polynomial arithmetic circuit connected to the disk array control circuit for calculating a parity including position information, a data string rearrangement circuit connected to the disk array control circuit and the polynomial arithmetic circuit, and the data string rearrangement circuit And a host interface circuit connected to the disk array device.