Storage sub-system and method for controlling the same

• US 20090083610A1
• Filed: 01/30/2008
• Published: 03/26/2009
• Est. Priority Date: 09/26/2007
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Arai, Masahiro, Nakamura, Shuji, Shimada, Kentaro
• Granted Patent: US 8,051,367 B2
• Time in Patent Office: Days
• US Class Current: 714/807
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 11/2089 Redundant storage control functionality
• CPC Class Codes: G06F 2211/1004 Adaptive RAID, i.e. RAID system adapts to changing circumstances, e.g. RAID1 becomes RAID5 as disks fill up
• CPC Class Codes: G06F 2211/1057 Parity-multiple bits-RAID6, i.e. RAID 6 implementations
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0641 De-duplication techniques
• CPC Class Codes: G06F 3/0643 Management of files
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]

Abstract

The present invention provides means for effectively reducing the amount of data by means of de-duplication in a disk array apparatus having a data guarantee code.

A control means for the disk array apparatus that adds a data guarantee code to each logical data block and checks the data guarantee code when reading data has a de-duplication performing function and control means for: generating LA substitution information for a function checking the data guarantee code or read data location address substitution information when performing the de-duplication and storing data; performing the de-duplication using the above-mentioned information when reading data; and thereby avoiding false diagnosis of the data guarantee code check.

Claims

1. A storage sub-system comprising:

a storage device;

memory including a control program; and

a controller for controlling a host computer'"'"'s access to the storage device to write/read data to/from the storage device in accordance with the control program;

wherein the controller generates a data guarantee code according to an inherent attribute of the data;

adds the data guarantee code to the data and writes the data to the storage device;

checks the data guarantee code to judge whether the data is error-free or not when reading the data from the storage device;

stores, if there are first data and second data as the data and the content of the first data and the content of the second data are the same, the first data together with the data guarantee code in the storage device without storing the second data in the storage device;

associates the host computer'"'"'s read access to the second data with the first data; and

has a change table for changing an inherent attribute of the second data so that the data guarantee code generated when processing the host computer'"'"'s read access to the second data, matches the data guarantee code of the first data.

2. The storage sub-system according to claim 1, wherein the controller:

includes a first logical volume accessed by the host computer and a second logical volume to which a storage area of the storage device is allocated;

writes the first data to a second logical address of the second logical volume in response to the host computer'"'"'s write access to a first logical address of the first logical volume;

reads the first data from the second logical address in response to the host computer'"'"'s read access to a third logical address of the first logical volume to read the second data;

generates the data guarantee code of the first data based on the second logical address;

includes a correspondence table that associates the first logical address and the third logical address with the second logical address respectively, and a table serving as the change table that changes the third logical address to the second logical address;

acquires the second logical address according to the correspondence table when processing the host computer'"'"'s read access to the second data;

acquires the second logical address from the third logical address according to the change table and generates the data guarantee code based on the second logical address when generating the data guarantee code in response to the read access to the second data; and

judges whether the then generated data guarantee code matches the data guarantee code added to the first data.

3. The storage sub-system according to claim 1, wherein the controller:

includes a first logical volume accessed by the host computer and a second logical volume to which a storage area of the storage device is allocated;

writes the first data to a second logical address of the second logical volume in response to the host computer'"'"'s write access to a first logical address of the first logical volume;

reads the first data from the second logical address in response to the host computer'"'"'s read access to a third logical address of the first logical volume to read the second data;

generates the data guarantee code of the first data based on the first logical address;

includes a correspondence table that associates the first logical address and the third logical address with the second logical address respectively, and a table serving as the change table that changes the third logical address to the first logical address;

acquires the second logical address according to the correspondence table when processing the host computer'"'"'s read access to the second data;

acquires the first logical address from the third logical address according to the change table and generates the data guarantee code based on the first logical address when generating the data guarantee code in response to the read access to the second data; and

judges whether the then generated data guarantee code matches the data guarantee code added to the first data.

4. The storage sub-system according to claim 2, wherein the second logical volume is a volume to which the storage capacity of the storage device is dynamically allocated in response to the host computer'"'"'s write access to the first logical volume.

5. The storage sub-system according to claim 3, wherein the second logical volume is a volume to which the storage capacity of the storage device is dynamically allocated in response to the host computer'"'"'s write access to the first logical volume.

6. The storage sub-system according to claim 1, wherein the controller judges based on a hash value whether the first data and the second data are the same or not.

7. The storage sub-system according to claim 1, wherein the inherent attribute of the second data is a logical address of a logical volume in which the second data is stored.

8. A storage sub-system comprising:

a storage device;

memory including a control program; and

a controller for controlling a host computer'"'"'s access to the storage device to write/read data to/from the storage device in accordance with the control program;

wherein the controller includes;

a first data guarantee code generator for generating a data guarantee code based on a first logical address of the data when writing the data to a logical volume in response to the host computer'"'"'s write access;

a data write unit for adding the data guarantee code to the data and writing the data to the storage device;

a second data guarantee code generator for generating a data guarantee code based on a second logical address designated by the host computer'"'"'s read access when reading the data from the logical volume in response to the host computer'"'"'s read access; and

a table that substitutes the first logical address for the second logical address;

wherein the second data guarantee code generator generates the data guarantee code based on the first logical address by referring to the table when the host computer reads the written data.

9. A method for controlling a storage sub-system comprising:

a storage device;

memory including a control program; and

a controller for controlling a host computer'"'"'s access to the storage device to write/read data to/from the storage device in accordance with the control program;

wherein the storage sub-system controlling method comprises the steps executed by the controller of;

generating a data guarantee code according to an inherent attribute of the data;

adding the data guarantee code to the data and writing the data to the storage device;

checking the data guarantee code to judge whether the data is error-free or not when reading the data from the storage device;

storing, if there are first data and second data as the data and the content of the first data and the content of the second data are the same, the first data together with the data guarantee code in the storage device without storing the second data in the storage device;

associating the host computer'"'"'s read access to the second data with the first data; and

changing an inherent attribute of the second data so that the data guarantee code generated when processing the host computer'"'"'s read access to the second data matches the data guarantee code of the first data.