Storage system and control method of the same

• US 20060080503A1
• Filed: 12/02/2004
• Published: 04/13/2006
• Est. Priority Date: 10/12/2004
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Yamagami, Kenji, Araki, Masanori
• Granted Patent: US 7,451,284 B2
• Time in Patent Office: Days
• US Class Current: 711/113
• CPC Class Codes: G06F 11/1456 Hardware arrangements for backup
• CPC Class Codes: G06F 11/3485 for I/O devices
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data
• CPC Class Codes: G06F 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/0653 Monitoring storage devices or systems
• CPC Class Codes: G06F 3/0656 Data buffering arrangements
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD

Abstract

The invention provides a storage system which can estimate a necessary capacity at the time of acquiring a snap shot copy without actually sampling the snap shot copy, and a control method of the same. In a storage system, a disk control unit monitors a write instruction from a host machine for a fixed period, and calculates a capacity necessary at the time of a snap shot, on the basis of the monitored information for the fixed period, in the case of receiving an instruction of calculating the capacity necessary at the time of acquiring the snap shot which makes it possible to refer to the data at a certain time point within a disk unit.

Claims

1. A storage system provided with a storage control unit and a disk unit comprised of a plurality of physical storage devices, wherein the storage control unit comprises:

a data transfer control unit controlling a data transfer with respect to a host machine and the disk unit;

a cache memory temporarily storing the data; and

a shared memory in which a configuration information of the storage system is stored, and

wherein, in the case of receiving an instruction of calculating a capacity necessary at the time of acquiring a snap shot which makes it possible to refer to the data at a certain time point within the disk unit, the storage control unit monitors a write instruction from the host machine for a fixed period, and calculates the capacity necessary at the time of the snap shot, on the basis of the monitored information for the fixed period.

2. The storage system according to claim 1, wherein when calculating the capacity necessary at the time of acquiring the snap shot, the storage control unit counts a number of an updated unit region within the disk unit on the basis of a write instruction from the host machine for the fixed period, and calculates the capacity necessary at the time of the snap shot on the basis of the count number and the capacity of the unit region.

3. The storage system according to claim 1, wherein the storage control unit manages information of the snap shot of a plurality of generations, and calculates a capacity considering a relation of the snap shot of the plurality of generations, in the case of calculating the capacity necessary at the time of acquiring the snap shot.

4. The storage system according to claim 3, wherein the storage control unit has a snap shot table managing information of a snap shot volume in which the snap shot of the plurality of generations is stored, and manages a relation of the snap shot of the plurality of generations on the basis of the snap shot table.

5. The storage system according to claim 4, wherein the storage control unit manages overlapping data in the snap shot of the plurality of generations in a sharing manner at the time of managing the relation of the snap shot of the plurality of generations.

6. The storage system according to claim 1, wherein the storage control unit displays a calculation result of the capacity necessary at the time of acquiring the snap shot on the host machine or a service processor connected to the storage system.

7. The storage system according to claim 6, wherein the storage control unit provides an operation plan of the snap shot on the basis of the calculation result of the capacity necessary at the time of acquiring the snap shot displayed on the host machine or the service processor connected to the storage system.

8. A storage system provided with a storage control unit and a disk unit comprised of a plurality of physical storage devices, wherein the storage control unit comprises:

a data transfer control unit controlling a data transfer with respect to a host machine and the disk unit;

a cache memory temporarily storing the data; and

a shared memory in which a configuration information of the storage system is stored, and

wherein, in the case of receiving an instruction of calculating a capacity necessary at the time of acquiring a snap shot which makes it possible to refer to the data at a certain time point within the disk unit, the storage control unit updates a difference bit map used at the time of the snap shot without executing an actual snap shot copy on the basis of a write instruction from the host machine, and calculates the capacity necessary at the time of the snap shot on the basis of update information of the difference bit map for a fixed period.

9. The storage system according to claim 8, wherein when calculating the capacity necessary at the time of acquiring the snap shot, the storage control unit acquires information of the difference bit map updated by the write instruction from the host machine for a fixed period, and calculates the capacity necessary at the time of the snap shot on the basis of the information of the updated bit number and the capacity of the unit region managed by the difference bit map.

10. The storage system according to claim 8, wherein when calculating the capacity necessary at the time of acquiring the snap shot, the storage control unit counts information of a bit off from the difference bit map updated on the basis of a write instruction from the host machine for the fixed period, and calculates the capacity necessary at the time of the snap shot on the basis of the information of the count number and the capacity of the unit region managed by the difference bit map.

11. The storage system according to claim 8, wherein the storage control unit manages information of the snap shot of a plurality of generations, and calculates the capacity considering a relation of the snap shot of the plurality of generations, in the case of calculating the capacity necessary at the time of acquiring the snap shot.

12. The storage system according to claim 11, wherein the storage control unit has a snap shot table managing information of a snap shot volume in which the snap shot of the plurality of generations is stored, and manages a relation of the snap shot of the plurality of generations on the basis of the snap shot table.

13. The storage system according to claim 12, wherein the storage control unit manages overlapping data in the snap shot of the plurality of generations in a sharing manner at the time of managing the relation of the snap shot of the plurality of generations.

14. The storage system according to claim 8, wherein the storage control unit displays a calculation result of the capacity necessary at the time of acquiring the snap shot on the host machine or a service processor connected to the storage system.

15. The storage system according to claim 14, wherein the storage control unit provides with an operation plan of the snap shot on the basis of the calculation result of the capacity necessary at the time of acquiring the snap shot displayed on the host machine or the service processor connected to the storage system.

16. A control method of a storage system provided with a storage control unit comprised of a data transfer control unit controlling a data transfer with respect to a host machine and a disk unit, a cache memory temporarily storing the data, and a shared memory in which a configuration information of the storage system is stored and with a disk unit comprised of a plurality of physical storage devices,

wherein, in the case of receiving an instruction of calculating a capacity necessary at the time of acquiring the snap shot which makes it possible to refer to the data at a certain time point within the disk unit, a write instruction from the host machine for a fixed period is monitored, and the capacity necessary at the time of acquiring the snap shot is calculated on the basis of the monitored information for the fixed period.

17. The control method of a storage system according to claim 16, wherein when calculating the capacity necessary at the time of acquiring the snap shot, a number of an updated unit region within the disk unit is counted on the basis of a write instruction from the host machine for the fixed period, and the capacity necessary at the time of the snap shot is calculated on the basis of the count number and the capacity of the unit region.

18. The control method of a storage system according to claim 16, wherein an information of the snap shot of a plurality of generations is managed, and a capacity considering a relation of the snap shot of the plurality of generations is calculated when calculating the capacity necessary at the time of the snap shot.

19. The control method of a storage system according to claim 18, wherein a snap shot table for managing information of a snap shot volume in which the snap shot of the plurality of generations is stored is used, and a relation of the snap shot of the plurality of snap shot is managed on the basis of the snap shot table.

20. The control method of a storage system according to claim 19, wherein the overlapping data in the snap shot of the plurality of generations in a sharing manner is managed at the time of managing the relation of the snap shot of the plurality of generations.