Storage System and Snapshot Data Preparation Method in Storage System

• US 20090216977A1
• Filed: 04/29/2009
• Published: 08/27/2009
• Est. Priority Date: 12/06/2004
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: WATANABE, Haruaki
• Granted Patent: US 8,095,822 B2
• Time in Patent Office: Days
• US Class Current: 711/162
• CPC Class Codes: G06F 11/0727 in a storage system, e.g. in a DASD or network based storage system drivers for digital recording or reproducing units G06F3/06; circuits for error detection or correction within digital recording or reproducing units G11B20/18; for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS], H04L67/1097
• CPC Class Codes: G06F 11/076 by exceeding a count or rate limit, e.g. word- or bit count limit
• CPC Class Codes: G06F 11/1471 involving logging of persistent data for recovery
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD

Abstract

The present invention is devised so that snapshot data preparation processing does not end abnormally as a result of the pool region becoming full with saved data from the primary logical volume during snapshot data preparation. When the CHA receives a snapshot data preparation request, the CHA checks whether or not update information is present in the logical volume that is the object of this data preparation. If such information is present (YES in S51), a check is made from the number of slots in the in the volume control information and the updating amount count value in the update information in order to ascertain whether or not the proportion of the updating amount relative to the number of slots is equal to or greater than the threshold value in the threshold value control information (S52). If this proportion is equal to or greater than the threshold value (YES in S52), the update information is initialized (S53), and physical snapshot control is started (S54). If such is not the case (NO in S52), the update information is initialized (S55), and logical snapshot control is started (S56).

Claims

1. A storage system comprising:

a physical snapshot execution part which writes data that has been updated into both a primary storage device and a secondary storage device;

a logical snapshot execution part which writes input data into said primary storage device, and which writes differential data between said data and data prior to updating into said secondary storage device, and

a snapshot execution part selection part which selectively drives said physical snapshot execution part when an amount of a plurality of differential data is greater than a value, and which selectively drives said logical snapshot execution part when amount of a plurality of differential data is less than said value.

2. The storage system according to claim 1, wherein said specified value is a preset threshold value relating to the amount of updated data, and said threshold value is a default value.

3. The storage system according to claim 1, wherein said specified value is a preset threshold value relating to the amount of updated data, and said threshold value can be freely set or altered by a user.

4. The storage system according to claim 1, wherein, prior to the driving of said physical snapshot execution part or said logical snapshot execution part, said snapshot execution part selection part initializes information relating to said data updating of said device involved in said snapshot data preparation request among information relating to the updating of data that is set for said first and second storage devices.

5. The storage system according to claim 1, wherein deletion of snapshot data that is prepared by said physical snapshot execution part or said logical snapshot execution part includes at least processing that initializes the information relating to the updating of said data of said primary storage device involved in said snapshot data preparation request.

6. The storage system according to claim 1, wherein the processing of writing data into said primary storage device based on a data write command from said higher-level device is accomplished by performing processing which indicates that data has been updated in information relating to the updating of data corresponding to said primary storage device.

7. A storage system comprising:

a physical snapshot execution part which writes data that has been updated into both a primary storage device and a secondary storage device;

a logical snapshot execution part which writes input data into said primary storage device, and which writes differential data between said data and data prior to updating into said secondary storage device; and

a snapshot execution part selection part which selectively drives said physical snapshot execution part when said access degree-of-competition judgment part judges that said access degree of competition is high, and which selectively drives said logical snapshot execution part when said access degree-of-competition judgment part judges that said access degree of competition is not high.

8. The storage system according to claim 7, wherein said access degree-of-competition judgment part judges whether said access degree of competition is high or not by checking a degree of utilization of said primary storage device involved in said snapshot data preparation request.