METHOD AND APPARATUS FOR REDUCING THE AMOUNT OF DATA IN A STORAGE SYSTEM

• US 20090043983A1
• Filed: 10/21/2008
• Published: 02/12/2009
• Est. Priority Date: 03/22/2006
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Yagawa, Yuichi
• Granted Patent: US 7,913,052 B2
• Time in Patent Office: Days
• US Class Current: 711/170
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/0638 Organizing or formatting or addressing of data
• CPC Class Codes: G06F 3/0641 De-duplication techniques
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]

Abstract

Groups of volumes having a certain amount of commonality of data are identified within a storage system. For each group, the process defines a base volume, such as the volume containing the most commonality with the other volumes. For each volume in the group, the process extracts differential data between the base volume and each other volume, saves the differential data in a pool volume, and updates a mapping table. Commonality between volumes in the group is managed in the base volume, the pool volume, and the mapping table. Then the original volumes except the base volume and the pool volume may be deleted, and the original volumes are replaced with virtual volumes accessible through the mapping table. As a result, the amount of data in a storage system can be reduced while maintaining data integrity and accessibility.

Claims

1. A method for managing data in a storage system comprising the steps of:

selecting a set of volumes in which an amount of stored data should be reduced, wherein said stored data are full data;

converting said selected set of volumes into a base volume and a virtual volume, wherein the total amount of actual disk space of the set of volumes are reduced after said conversion.

2. The method according to claim 1,

wherein said set of volumes include a set of copy generation volumes,

wherein said virtual volume includes a mapping table and a pool volume.

3. The method according to claim 1,

wherein said selecting is performed based on configuration information of data replication.

4. The method according to claim 3,

wherein said selecting is performed by the system automatically.

5. The method according to claim 1,

wherein during said conversion write I/Os are buffered.

6. The method according to claim 1, further comprising the step of:

deleting other volumes other than said pool volume and base volume so as to reduce the amount of data stored in said storage system

7. The method according to claim 5,

wherein said selecting is performed by determining a group of volumes having a commonality of data,

wherein said base volume includes said data having commonality and said pool volume includes extracted differential data between the base volume and each other volume in said group, and wherein said mapping table includes information regarding a location of the differential data in said pool volume.