Disk array system, host interface unit, control method for disk array system, and computer program product for disk array system

Abstract

A disk array system includes a dedicated cache memory, a first host computer exclusively using the dedicated cache memory, data for a dedicated disk being written to or being read from the dedicated cache memory. The disk array system is connectable to the first host computer and to a second host computer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary features and advantages of the present invention will become apparent from the following detailed description when taken with the accompanying drawings in which:

FIG. 1 is an exemplary schematic block diagram of exemplary disk array system 1;

FIG. 2 is an exemplary detailed block diagram of exemplary disk array system 1;

FIG. 3 is an exemplary flowchart showing an exemplary operation of exemplary disk array system 1 upon receiving a read command from host computer 2;

FIG. 4 is an exemplary flowchart showing an exemplary operation of exemplary disk array system 1 upon receiving a write command from host computer 2;

FIG. 5 is an exemplary flowchart showing an exemplary write-back operation performed by exemplary disk array system 1;

FIG. 6 is an exemplary block diagram showing a state where exemplary host interface units 10a and exemplary logical disks 4a are additionally provided to exemplary disk array system 1;

FIG. 7 is an exemplary flowchart showing another exemplary operation of exemplary disk array system 1 upon receiving a write command from host computer 2;

FIG. 8 shows an example of data included in exemplary logical disk access information 11 and 21;

FIG. 9 is a block diagram showing a configuration of conventional large-scale disk array system 200; and

FIG. 10 is a block diagram showing a configuration of conventional storage subsystem 210.

Claims

1. A disk array system, comprising: a dedicated cache memory, a first host computer exclusively using said dedicated cache memory, data for a dedicated disk being written to or being read from said dedicated cache memory,wherein said disk array system is connectable to said first host computer and to a second host computer.

2. The disk array system according to claim 1, further comprising: said dedicated disk, data for said dedicated disk, that has been written in said dedicated cache memory, being written to the dedicated disk.

3. The disk array system according to claim 2, further comprising: a host interface unit that includes said dedicated cache memory, said first host computer exclusively using said host interface unit,wherein, when said host interface unit receives a command for writing data to or reading data from said dedicated disk from said first host computer, said host interface unit writes said data to or reads said data from said dedicated cache memory.

4. The disk array system according to claim 3, further comprising: a shared cache memory, said first host computer and said second host computer sharing said shared cache memory,wherein, when said host interface unit receives a command for writing data or reading data from a shared disk, said host interface unit writes said data to or reads said data from said shared cache memory.

5. The disk array system according to claim 4, further comprising: said shared disk, said first host computer and the second host computer sharing the shared disk.

6. The disk array system according to claim 5, further comprising: a disk interface unit that includes said shared cache memory, wherein:when said disk interface unit receives said command for writing data to or reading data from said shared disk, from said host interface unit, said disk interface unit writes said data to or reads said data from said shared disk; andwhen said disk interface unit receives said command for writing data to or reading data from said dedicated disk, from said host interface unit, said disk interface unit writes said data to or reads said data from said dedicated disk.

7. The disk array system according to claim 3, wherein: said host interface unit includes host interface cards, each of host interface cards including said dedicated cache memory; andsaid host interface unit writes data to said dedicated cache memory only when all said host interface cards are in normal operation.

8. The disk array system according to claim 6, further comprising: a disk access information that indicates which of said dedicated disk and said shared disk is a target disk of a command for writing data to or reading data from,wherein said host interface unit determines whether said target disk is said dedicated disk or said shared disk, by referring to said disk access information.

9. A host interface unit, comprising: a dedicated cache memory, a first host computer exclusively using said dedicated cache memory, data for a dedicated disk being written to or being read from said dedicated cache memory,wherein a disk array system includes said host interface unit and said disk array system is connectable to said first host computer and to a second host computer.

10. A control method for a disk array system, comprising: receiving one of a write command and a read command for a target disk from a first host computer;executing one of said write command and said read command to a dedicated cache memory exclusively used by said first host computer, when said target disk includes said dedicated disk exclusively used by said first host computer; andexecuting one of said write command and said read command to a shared cache memory shared by said first host computer and said second host computer, when said target disk includes a shared disk shared by said first host computer and said second host computer.

11. The control method for a disk array system according to claim 10, further comprising: receiving said write command for said target disk from said first host computer;executing said write command to said shared cache memory, when one of host interface cards, each host interface cards including said dedicated cache memory, is out of normal operation, even when said target disk includes said dedicated disk.

12. A computer program product including a program for causing a control portion of a disk array system to perform the method of claim 10.