JP2001155409A - Access method for array type disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent that a data transfer band is occupied for restoring the data when a specified disk type storage medium breaks down in a video server. SOLUTION: The disk type storage media (HDD) 1-1 to 1-5 are provided as a disk array 1, and an erroneous data restoring disk type storage medium 1-6 for parity is provided. Then, a program being a continuous body of the fame data are recorded successively on HDD 1-1,..., HDD 1-5, HDD 1-1,..., HDD 1-5 in frame. At an N-fold high speed reproducing time, the data of one frame are read out respectively from prescribed HDDs at every N frame to be joined to each other. When the specified HDD breaks down, the HDD recording the data of an adjacent frame is selected instead of taking out the frame data of a number recorded on the relevant HDD, and the data are replaced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an access method for an array type disk drive having a plurality of disk type storage media and one disk type storage medium for parity.

[0002]

2. Description of the Related Art Conventionally, an array type disk device having a plurality of disk type storage media and one parity type disk type storage medium has been used as a video server.
Here, an overview of the functions of the video server will be described.

[0003] Video servers are mainly broadcast stations and CATV.
It is also used in museums, memorial halls, amusement parks, etc., depending on its type. In the configuration, a disk type storage medium (HDD) including a hard disk and a drive circuit is used instead of a video deck and a cassette tape like a VTR. In other words, instead of linearly accessing a tape-shaped recording medium like a magnetic tape, an HDD or a CD-R
Direct access to a disk-shaped recording medium, such as an OM playback device, is a necessary condition for a video server.

The functions of the video server include (1) recording video and audio data on a recording medium, and (2) instantly distributing video and audio data recorded on the recording medium upon an external request. There is. Since such a recording medium is not a linear medium, the recorded data can be reproduced (chase-up reproduction) immediately after recording the data.

When video and audio data are handled by a video server, data is processed in units of frames as shown in FIG. The frame here means a period of 1/30 seconds in the case of the NTSC broadcast format, and a period of 1/25 seconds in the case of the PAL broadcast format. This frame is 1
Video and audio data are recorded and read out on a recording medium as a unit.

FIG. 3 is a block diagram of a conventional video server, which is a RAID (Redundant Array of Inexpensive Disk).
s). The disk array 1 of the video server has a plurality of disk-type storage media (HDDs). Here, a disk-type storage medium 1-1, a disk-type storage medium 1-2, a disk-type storage medium 1-3, Disk type storage medium 1-4, disk type storage medium 1-5,
And a disk type storage medium for parity 1-6. The control unit 2 also includes a writing unit 2-1 for writing data to disk-type storage media (hereinafter simply referred to as HDDs) 1-1 to 1-5 by time-sharing video and audio data in accordance with the parity. And an input / output means 2-3 for inputting / outputting video and audio data to / from the outside.
The parity data is recorded on the parity disk storage medium 1-6 so as to correspond to video and audio data.

One program is composed of frames k, k + 1, k +
.. (K is an integer of 1, 2,...), The HDD 1-1 stores the data of the k-th frame,
The HDD 1-2 stores the data of the (k + 1) th frame.
DD1-3 stores the data of the (k + 2) th frame, and
D1-4 stores the data of the (k + 3) th frame, and
1-5 stores the data of the (k + 4) th frame. Thus, the frame number K (K = 1, 2,..., 5, 6, 7,...)
. 10, 11, 12.
Record to DD in real time. The control unit 2 and the disk array 1 are connected by a data bus (for example, SCSI). Such writing or reading of frame data is processed in real time by the writing means 2-1 or the reading means 2-2 as long as the data rate is within the range of the data transfer rate of the data bus.

The method of using the parity disk type storage medium 1-6 differs depending on the RAID level. RAID
In the case of -1, the same data is recorded on two HDDs by mirroring, and the processing can be continued even if a failure occurs in one of the HDDs. In RAID-2, data is recorded on N HDDs, and ECC data based on a Hamming code is recorded on another HDD. In this case, a specific HDD
Even if an error occurs in the data due to the failure, the data can be correctly corrected. In RAID-3, when data is recorded on N HDDs, a parity HDD is further provided, and striping is performed in units of 1 bit or 1 byte of data. In RAID-5, N + 1 HDDs are provided as described above, data is recorded in N HDDs, and parity is not fixedly assigned to the other HDD, but is divided into N HDDs. By dispersing the parity, simultaneous rewriting at two or more locations is possible. The disk array 1 shown in FIG.
Equivalent to 3.

Here, a method for reproducing video and audio data will be described. As shown in FIG.
It is assumed that HDD-1 to HDD1-6 are provided. (1) First, the data of the frame 1 is read from the HDD 1-1 by the reading means 2-2. (2): Next, the data of the frame 2 is read from the HDD 1-2. (3); Next, the data of the frame 3 is read from the HDD 1-3.
(4); Next, the data of the frame 4 is read from the HDDs 1-4. Similarly, (5); the data of frame k is transferred to HD
Read from D1-1. Next, data of the frame k + 1 is read from the HDD 1-2. In this way, the video and audio data to be output are read out in frame order.

Next, an operation of performing special reproduction of video and audio data in a conventional video server will be described.
Here, it is assumed that high-speed reproduction of, for example, 5 times speed is performed, and that a specific HDD (HDD 1-1) is out of order.

(1) First, reading is started from the data of frame 1. However, the data of frame 1 is stored in HDD
Since the data cannot be read from the HDD 1-1, the HDD 1-2
.. HDD1-6 are read simultaneously, parity calculation is performed using the data of the parity disk, and the data of frame 1 is restored. The input / output means 2-3 transfers or distributes the restored video and audio data of the frame 1 to the outside. (2): Next, reading of data of frames 2 to 5 is skipped, and reading of data of frame 6 is started. Also in this case, the data of the frame 6 cannot be read from the HDD 1-1.
1-2, the data of the HDD 1-6 are simultaneously read, and the data of the frame 6 is restored using the data of the HDD 1-6 for parity. The input / output means 2-3 transfers or distributes the restored video and audio data of the frame 6 to the outside. (3) Similarly, for the frames 11 and 16, the data of the HDDs 1-2 to 1-6 are simultaneously read out, and the data of the frames 11 and 16 are respectively restored using the data of the parity disk.

[0012]

As described above, in the worst case, it is necessary to simultaneously read data from five HDDs in order to extract one frame of video and audio data, and the bit rate of the data bus is limited. It may exceed the value. When a particular HDD during reproduction of normal reproduction (1x speed) fails, to simultaneously access data from other five HDD, when the transfer bit rate of the data bus becomes B _MAX, the video server data bus maximum transfer bit rate is often set to B _MAX. In order to ensure the maximum transfer bit rate B _MAX , the SCSI (SCSI, SCSI-2, SCSI
-3) is set or selected. If such a specific HDD under environment when high-speed reproduction of the 5-speed fails, the maximum transfer bit rate of the data bus exceeds the permissible value B _MAX. In such a case, there has been a problem that the signal processing of the video server itself is temporarily interrupted or a video signal of a specific frame is not output.

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional problem, and in a special reproduction such as a high-speed reproduction of a video, a specific HDD among a plurality of HDDs is broken. It is another object of the present invention to provide an access method for an array type disk device that can output a video signal and reduce the occupation of a data transfer band on a data bus.

[0014]

According to the first aspect of the present invention, video data and audio data are sequentially recorded on a disk array composed of a plurality of disk-type storage media on a frame-by-frame basis. An access method of an array type disk device to be reproduced, wherein when it is not possible to read recorded data from a specific disk type storage medium during high speed reproduction, the specific disk type storage medium and another disk type storage medium adjacent on the frame are read out. Read the recorded data,
It is characterized by replacing with frame data of the specific disk type storage medium.

According to a second aspect of the present invention, a disk array comprising a plurality of disk-type storage media and one parity-type disk-type storage medium stores video and audio data on a frame-by-frame basis in each disk-type storage medium. An access method of an array type disk device for sequentially recording or reproducing, wherein when high-speed reproduction cannot read recorded data from a specific disk type storage medium, another disk type adjacent to the specific disk type storage medium on a frame. The recording data is read from the storage medium and replaced with the frame data of the specific disk type storage medium.

According to a third aspect of the present invention, in the access method of the array type disk device according to the second aspect, the disk array satisfies the RAID-3 standard.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A configuration of an array type disk device (video server) and an access method thereof according to an embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a configuration diagram of a video server according to the present embodiment, which has a RAID-3 format as in the conventional example. The disk array 1 of the video server has a plurality of disk-type storage media (HDD), and the disk-type storage medium 1-1 (HDD1-1) and the disk-type storage medium 1-2 (HDD) as in the conventional example. HDD 1-2), disk type storage medium 1-3 (HDD 1-3), disk type storage medium 1-4 (HDD 1-4), disk type storage medium 1-5
(HDD 1-5) and a disk type storage medium for parity 1-6 (HDD 1-6).

The control unit 3 writes data 3-1 into the HDDs 1-1 to 1-5 by dividing the video and audio data in a time-division manner.
Reading means 3-2 for reading out video and audio data in a time-division manner corresponding to the HDD 1-6 parity data, and input / output means 3 for inputting and outputting video and audio data to the outside
-3.

One program is composed of frames k, k + 1, k +
2, k + 3, k + 4, k + 5,... (K is an integer of 0, 1, 2,...), The HDD 1-1 stores the k-th frame as in the conventional example. HDD1-2 stores data of the (k + 1) th frame, HDD1-3 stores data of the (k + 2) th frame, HDD1-4 stores data of the (k + 3) th frame, and HDD1-5 stores data of the (k + 4) th frame. The frame data is stored. Thus, the frame number K (K = 1, 2 ·
.., 5, 6, 7,..., 10, 11, 12,...) Are divided into remainders of 5, and the input video and audio data are recorded in frame units in real time in respective HDDs. The control unit 3 and the disk array 1 are connected by a data bus (SCSI) having a predetermined bit rate. The writing of the frame data is performed within the range of the data transfer rate of the data bus if the writing means 3-1 is used.
Is processed in real time.

If the six HDDs are normal, the recording method of the video and audio data constituting the program is the same as in the conventional example, and the frame data is recorded on each HDD corresponding to the frame number. A reproduction method (access method) when a specific HDD fails during special reproduction of a program will be described below.

Here, it is assumed that the HDD 1-1 is out of order, and special reproduction at 5 × speed is performed. (1) Since the data of the frame 1 cannot be read from the HDD 1-1, the control unit 3 issues an instruction to the reading unit 3-2, and
The data of D1-2 is read. The input / output unit 3-3 outputs data of the frame 2 to the outside as an alternative to the frame 1. (2) Next, although the data of frame 6 is required, since the data of frame 6 cannot be read from HDD 1-1, control unit 3 issues an instruction to reading means 3-2 to read the data of HDD 1-2. read out. Input / output means 3
-3 outputs the data of frame 7 to the outside as an alternative to frame 6. (3) Next, although the data of the frame 11 is required, the data of the frame 11 cannot be read from the HDD 1-1.
-2 to read the data of the HDD 1-2.
The input / output unit 3-3 outputs the data of the frame 12 to the outside as a substitute for the frame 11.

By continuing such an access, frames 1 and 2
Instead of reproducing the data of 6, 11, 16, and 21, the data of frames 2, 7, 12, 17, and 22 are reproduced.
In fast-forward playback, the difference of one frame is not so important, so that the user of the video server hardly feels uncomfortable with the playback image. According to such an access method, the data from one HDD is transferred, the transfer bit rate of the data bus without exceeding the B _MAX, reduction of interruptions and the processing speed of the data processing does not occur.

The above operation is an example in which the speed ratio 5 is equal to the number of HDDs (5) for storing data, but the same operation can be performed when another speed ratio is set. . For example, it is assumed that the speed ratio is 3, the number of HDDs for storing data is 5, and the HDD 1-1 is out of order. In this case, the data of the frame 1 is substituted by the data of the HDD 1-2, the data of the frame 4 is the data of the HDD 1-4, the data of the frame 7 is the data of the HDD 1-2, and the data of the frame 10 is the HDD 1--1. 5 data may be used. That is, if the data can be read from the regular HDD, the data is used. If the data cannot be read from the regular HDD, the substitute data is read from the HDD in which the data of the adjacent frame is recorded. You just have to put it out. Also, a parity HDD 1-
6, parity data can be recorded together with the frame data in the HDD 1-1 to HDD-5. The operation at the time of high-speed reproduction in this case is the same as in the above-described embodiment.

[0024]

As described above, according to the present invention, when data cannot be read from a specific disk-type storage medium during high-speed reproduction, another disk-type storage medium adjacent to the specific disk-type storage medium on a frame. Parity restoration processing can be avoided by reading recorded data from the medium and replacing it with frame data of a specific disk type storage medium. This eliminates the need to access data from a plurality of disk-type storage media at one time, and has an advantageous effect of reducing the occupation of the data transfer band.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a video server according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a frame configuration of video and audio signals.

FIG. 3 is a configuration diagram of a conventional video server.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Disk array 1-1-1-5 Disk type storage medium (HDD) 1-6 Parity disk type storage medium (HDD) 3 Control part 3-1 Writing means 3-2 Reading means 3-3 Input / output means

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G11B 20/18 570 G11B 20/18 570L H04N 5/76 H04N 5/76 A 5/765 5/781 510J 5/781

Claims (3)

[Claims] 1. An access method for an array-type disk device for sequentially recording or reproducing video and audio data on a disk array comprising a plurality of disk-type storage media on a frame-by-frame basis on each disk-type storage medium, When the recording data cannot be read from the specific disk-type storage medium during high-speed playback, the recording data is read from another disk-type storage medium adjacent to the specific disk-type storage medium on the frame, and the frame of the specific disk-type storage medium is read. An access method for an array-type disk device, wherein the method is replaced with data. 2. An array type for sequentially recording or reproducing video and audio data on a disk array comprising a plurality of disk type storage media and one parity type disk type storage medium in frame units. An access method for a disk device, comprising reading recorded data from another disk-type storage medium adjacent to the specific disk-type storage medium on a frame when the recording data cannot be read from the specific disk-type storage medium during high-speed reproduction. An access method for an array type disk device, wherein the method is replaced with frame data of the specific disk type storage medium. 3. The access method according to claim 2, wherein the disk array satisfies the RAID-3 standard.