JPH10293656A - Disk storage system and duplexing method applied to the storage system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the increase of the data transfer load of a system bus and to improve the total data transfer efficiency for a duplex disk storage system. SOLUTION: This duplex disk storage system uses a master HDD 6A and a subordinate HDD 6B, for example, as the disk storages. In this system, the transfer of data is controlled to both HDD 6A and 6B by a channel device 3 which is connected to a system bus 8 of a host computer. The device 3 serves as a common means between both HDD 6A and 6B and contains the data registers 4A and 4B which hold the write data WD inputted via the bus 8 in response to the command of the host computer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a disk storage system in which a disk storage device such as a hard disk device is duplicated.

[0002]

2. Description of the Related Art Conventionally, in a computer system, a hard disk drive (HDD) is generally used as an external storage device for storing a large amount of data. Here, among computer systems, for example, in a storage system connected to a host computer (server or the like) used for a network or an online system, a duplex configuration is adopted to ensure protection of stored data. There are many cases.

[0003] More specifically, as shown in FIG. 4, a plurality of channel devices (# 1, # 2) 9A, 9B connected to a system bus 8 of a host computer, as shown in FIG.
Having. The host computer has a CPU 1 and a main memory 2 (other components are omitted). The channel devices (# 1, # 2) 9A, 9B correspond to, for example, an interface controller of the SCSI interface specification.

[0004] Each of the channel devices 9A, 9B has a disk drive (HDD) 6A, 6 whose input / output control is performed by a disk controller (HDC) 5A, 5B, respectively.
Data recording and reproduction (write operation and read operation) are performed on B. In the duplex system, one HDD 6A is set as a master drive, and the other HDD 6B is set as a sub drive.

[0005] The CPU 1 issues a write command when data is stored in the HDD. That is, the CPU 1 issues a write operation start command to the channel device 9A. Similarly, the CPU 1 issues a write operation start command to the channel device 9B. The channel device 9A reads the write data stored in the main memory 2 and
Output to C5A. By the input control of the HDC 5A,
The master HDD 6A stores the write data from the CPU 1. Similarly, the channel device 9B reads out the write data stored in the main memory 2 and outputs it to the HDC 5B. By controlling the input of the HDC 5B, the sub HDD 6B
Saves the write data from the CPU 1.

With such a duplex system, the CPU
The same data from 1 is the master HDD 6A and the sub HDD
6B, data can be reliably protected even if one HDD fails.

In the duplex system, the system bus 8 is connected to each channel device (# 1, # 1) as shown in FIG.
# 2) Since 9A and 9B execute the access operation at the same time, the load of data transfer is doubled. For example, the data transfer capability of the system bus 8 is “25 MB / s”, and the data transfer capability of each channel device (# 1, # 2) is “5 MB / s”.
s ”. Therefore, the available capacity of the system bus 8 is “1”.
5 MB / s ".

Here, when the duplex system is expanded, the load is doubled with respect to the data transfer capacity "25 MB / s" of the system bus 8, so that the free capacity of the system bus 8 is "5 MB / s". Become.

[0009]

In the conventional disk storage system of the duplex system, since each channel device performs data transfer at the same time, the data transfer capability of the system bus is usually (single HDD for accessing one HDD).・ It is necessary to assume twice the load of the system. Therefore,
While the degree of security for data protection is increased by the duplex system, the data transfer load on the system bus increases, and the efficiency of data transfer processing related to other data processing decreases.

It is an object of the present invention to improve the efficiency of the data transfer process as a whole by suppressing an increase in the data transfer load of the system bus in a disk storage system of a duplex system.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a duplex type disk storage system using a HDD as a disk storage device and having a master HDD and a sub HDD. The present system uses a master HD by channel control means connected to the system bus of the host computer.
The control of data transfer to D and the sub HDD is executed.
The channel control means is a common means for the master HDD and the sub HDD, and controls transfer of write data in response to a command from the host computer. The channel control means has data register means, holds write data input in response to the write command, and stores the master HDD and the sub HDD.
Forward to both.

In the dual disk storage system having such a configuration, when data is stored in the master HDD and the sub HDD, the channel control means transmits only write data corresponding to one HDD via the system bus. And enter
It is held in the data register means. Therefore, multiple HDDs
, The data transfer load on the system bus can be suppressed to the same extent as in a normal single system. In other words, a normal single
With the same hardware as the system, the data protection function of the duplex system and the data transfer efficiency of the system bus in the single system can be achieved.

Here, as the data register means, a structure provided corresponding to each of the master HDD and the sub HDD can improve data transfer efficiency. Also, if the data register means is shared by the master HDD and the sub HDD, the hardware can be reduced.

Further, when a read command is issued from a host computer, the present system
The designated data is preferentially read from the DD and transferred to the host computer via the system bus. Master HD
If the read data read from D is erroneous (a read error has occurred), the specified data is read from the sub HDD and transferred to the host computer via the system bus.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a system configuration related to the present embodiment, and FIG. 2 is a flowchart for explaining the operation of the present embodiment. (System Configuration) As shown in FIG. 1, the disk storage system of this embodiment has a channel device 3 connected to a system bus 8 of a host computer. The channel device 3 is a common device for the master HDD 6A and the sub HDD 6B, and controls data transfer to each of the HDDs 6A and 6B. Data input / output control of each of the HDDs 6A and 6B is executed by disk controllers (HDC) 5A and 5B, respectively.

The channel device 3 of the present embodiment includes
It has data registers 4A and 4B corresponding to 6A and 6B. The data registers 4A and 4B are data buffers used to hold write data input via the system bus 8 and to hold read data and output it to the system bus 8.

Here, the host computer has a CPU 1 and a main memory 2 in addition to the system bus 8. In the present embodiment, the other components are not related, and the description is omitted. (Operation and Effect of this Embodiment) The operation and effect of this embodiment will be described below with reference to the flowchart of FIG. 2 and FIG. 3 together with FIG.

The CPU 1 of the host computer issues a write command and write data to the channel device 3 when storing data in the HDD, which is an external storage device, with the data processing (YES in steps S1 and S2). .

The channel device 3 reads the write data WD from the main memory 2 written by the CPU 1 and sets it in the data registers 4A and 4B (step S3).
S4). That is, the write data WD read from the main memory 2 is transferred by the system bus 8 and input to the channel device 3.

The HDC 5A controls the write operation so that the write data WD transferred from the data register 4A is written to the disk 7A of the master HDD 6A together with the write command from the channel device 3 (step S).
5). On the other hand, the same write data WD as the master HDD 6A is also recorded on the disk 7B of the sub HDD 6B.
That is, the HDC 5B controls the write operation so that the write data WD transferred from the data register 4B is written to the disk 7B of the sub HDD 6B together with the write command from the channel device 3.

Next, the CPU 1 of the host computer
When reading specified data from the HDD, a read command is issued (NO in steps S1 and S2). The channel device 3 gives priority to the master H in response to the read command.
Control for accessing DD6A is performed (step S6). The HDC 5A is the disk 7 of the master HDD 6A.
The designated data is read from the data group recorded in A and output to the channel device 3 (step S7).

Here, by the error processing of the HDC 5A,
When a read error occurs in which the read data read from the master HDD 6A becomes an error, the channel device 3 switches the access target to the sub HDD 6B (YES in step S8, S9). Therefore, HDC5B is
The designated data (same as that stored in the master HDD 6A) is read from the disk 7B of the sub HDD 6B and output to the channel device 3 (step S10).

The channel device 3 sets the read data output from the HDC 5A in the data register 4A, or sets the read data output from the HDC 5B in the data register 4B (step S11). And
The channel device 3 outputs the read data held in the data register 4A or 4B to the system bus 8 (Step S12). Normally, read data is stored in the main memory 2 and used by the CPU 1.

As described above, according to the present embodiment, when writing the write data WD to both the master HDD 6A and the sub HDD 6B in response to a write command from the host computer, the channel device 3 is connected to the system bus 8
Write data WD input from the data register 4A,
4B and output to each of the HDDs 6A and 6B. Therefore, as shown in FIG. 3, the system bus 8 at the time of this write operation has the data transfer capability "5 MB / s" of the channel device 3 as in the case of a single system accessing one ordinary HDD. There is only a corresponding data transfer load. Therefore, when the data transfer capability of the system bus 8 is set to “25 MB / s”,
Has an available capacity of “20 MB / s”. That is, in the duplex system of the present embodiment, the normal system (one HDD)
Data access load of the system bus 8 does not need to be doubled for a single system that accesses the system).

In other words, in the duplex system of the present embodiment, if the system bus has the same data transfer capability,
As compared with the conventional method, the vacant capacity of the system bus for data transfer is increased. Therefore, the data transfer efficiency accompanying other data processing of the host computer is relatively increased.

In this embodiment, the master HDD 6A
The case where the data registers 4A and 4B are provided in correspondence with the sub HDD 6B and the sub HDD 6B has been described. However, when the data register is also used, the channel device 3 alternately reads the write data held in the data register and transfers it to each of the master HDD 6A and the sub HDD 6B. Therefore, the data transfer efficiency from the channel device 3 to the HDDs 6A and 6B is reduced as compared with the case of the present embodiment.

[0027]

As described above in detail, according to the present invention, 2
In a redundant type disk storage system, a data protection function for duplicating data storage can be realized, and an increase in data transfer load on a system bus can be suppressed as compared with a normal system. Therefore, when the system of the present invention is applied to a computer system, the data transfer efficiency of the system bus can be improved as a whole as compared with the conventional duplex system. Accordingly, when the present invention is applied particularly to a computer system that requires a duplex system, it is possible to reliably protect data and achieve a relative improvement in data transfer efficiency, thereby improving data processing efficiency.

[Brief description of the drawings]

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

FIG. 2 is a flowchart for explaining the operation of the embodiment.

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

FIG. 4 is a block diagram showing a conventional system configuration.

FIG. 5 is a conceptual diagram for explaining the operation and effect of the conventional system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... CPU (Host computer) 2 ... Main memory 3 ... Channel device 4A, 4B ... Data register 5A, 5B ... Disk controller (HDC) 6A ... Master HDD (disk drive) 6B ... Sub HDD (disk drive) 7A, 7B ... Disk 8: System bus

Claims (6)

[Claims] 1. A disk storage system for recording and reproducing data to and from each disk storage device of a duplex configuration in response to a command from a host computer, wherein a system bus is provided in accordance with a write command included in the command. Data register means for holding the write data transferred via the CPU, channel control means for outputting the write data held in the data register to each of the disk storage devices, and for each of the disk storage devices A disk control system provided with drive control means for inputting write data output from the channel control means to a disk storage device to be controlled and recording the write data on a recording medium. 2. The apparatus according to claim 1, wherein said data register means is provided for each of said disk storage devices, and is configured to hold write data corresponding to each of said disk storage devices. Disk storage system. 3. The data register according to claim 1, wherein said data register means is a common register for each of said disk storage devices, and is configured to alternately read held write data. Disk storage system. 4. A disk storage system having a master disk storage device and a sub disk storage device, and recording and reproducing data to and from each of the master and sub disk storage devices in response to a command from a host computer. Data register means for holding write data transferred via a system bus when the command from the host computer is a write command, which is a common means of the master disk storage device and the sub disk storage device. Channel control means for outputting write data held in the data register to each of the master and sub disk storage devices, and control means corresponding to each of the master and sub disk storage devices; The write data output from the Enter the storage device and the sub-disk storage, disk storage system characterized by comprising a drive control means for recording the same data to each recording medium. 5. When the command from the host computer is a read command, the channel control means
Means for preferentially reading specified data from the master disk storage device via the drive control means, storing the designated data in the data register means, and transferring the data to the host computer via the system bus. 4. The disk storage system according to claim 3, wherein: 6. A disk storage system for recording and reproducing data in response to a command from a host computer with respect to a disk storage device having a dual configuration having a master disk storage device and a sub disk storage device, A duplex method applied to a disk storage system including a channel control unit connected to a host computer via a system bus and having a data register unit for temporarily holding read data and write data, When the command from the host computer is a write command, the channel control unit sets write data transferred via the system bus in the data register unit; and a write held in the data register unit. Transfer data to the master and sub disks And it outputs the 憶 device, duplex method and executes a process of recording the same data to each recording medium.