Using duplicated data to enhance data security in RAID environments

Patent metadata

Field	Value
Publication number	US-9645897-B2
Application number	US-201514644328-A
Country	US
Kind code	B2
Filing date	Mar 11, 2015
Priority date	Mar 11, 2015
Publication date	May 9, 2017
Grant date	May 9, 2017

Abstract

A method for processing a data object access request in a storage system having storage devices can include receiving an access request for accessing a first data object, the request being received by a controller that stores at least two consecutive data objects received by the storage system in different storage devices. The method may then include detecting that the first data object is corrupted, and determining, in response to the detecting, that a second data object has identical data as the first data object. Determining that the second data object has identical information as the first data object can include determining that a first metadata tag corresponding with the first data object and a second metadata tag corresponding with the second data object are identical. The second data object can then be provided in a response to the access request.

First claim

What is claimed is:

1. A method for processing a data object access request in a storage system, comprising:
generating a data duplication database having metadata tags and associated data object identifiers to identify data objects stored on the storage system, wherein generating the data duplication database comprises,
generating a first metadata tag uniquely corresponding with a particular pattern of bits stored in a first data object stored on the storage system,
associating the first metadata tag with a first data object identifier identifying the first data object, and
storing the first metadata tag and the first data object identifier in a first record of the data duplication database;

receiving an access request for accessing a second data object, the request being received by a controller that stores at least two consecutive data objects received by the storage system on different storage devices;
detecting that the second data object is corrupt;
determining, in response to the detecting, that a third data object has identical data as the second data object, wherein the determining includes,
determining that the data duplication database has both a second metadata tag uniquely corresponding with a particular patterns of bits stored in the second data object and a third metadata tag uniquely corresponding with a particular pattern of bits stored in the third data object, and
determining that both the second metadata tag and the third metadata tag are identical; and

providing the third data object in a response to the access request.

2. The method of claim 1 , further comprising updating the data duplication database each time a new data object is updated or stored on the storage system, wherein updating the data duplication database comprises:
generating a fourth metadata tag corresponding with a particular pattern of bits stored in the new data object,
associating the fourth metadata tag with a second data object identifier identifying the new data object, and
storing the fourth metadata tag and the second data object identifier in a second record of the data duplication database.

3. The method of claim 2 , wherein the data duplication database is updated by scanning the storage system.

4. The method of claim 1 , wherein the data duplication database includes records of data objects generated by the storage system.

5. The method of claim 1 , further comprising:
storing a fourth data object on a first storage device; and
storing a fifth data object, having identical data as the fourth data object, on a second storage device.

6. A computer-implemented method for reconstructing data stored on a failed storage device of a redundant array of independent disks (RAID) type storage system having two or more storage devices, comprising:
determining that a first data object stored on a first storage device requires reconstruction on a second storage device, wherein the first storage device is determined to inaccurately store at least one unit of data and the second storage device is designated to replace the first storage device;
retrieving both a first metadata tag corresponding to a particular pattern of bits stored in the first data object and a second metadata tag corresponding with a particular pattern of bits stored in a second data object from a data duplication database, wherein,
the data duplication database comprises records, each record having both a data object identifier to identify each data object stored in the storage system and a metadata tag corresponding with a particular pattern of bits of stored in each data object,
the second data object is stored on a different storage device than the first storage device, and
the first metadata tag and the second metadata tag are generated by applying a hash function respectively to the first data object and the second data object;

determining whether the first metadata tag is identical to the second metadata tag;
storing the second data object on the second storage device when the first metadata tag is identical to the second metadata tag; and
reconstructing the first data object using a RAID data reconstruction method and storing the reconstructed first data object on the second storage device when the first metadata tag is different from the second metadata tag.

7. The method of claim 6 , wherein the RAID data reconstruction method uses parity information and a third data object, each of which is stored on a different storage device than the first storage device.

8. The method of claim 6 , further comprising updating the data duplication database each time a new data object is updated or stored on the storage system, wherein updating the data duplication database comprises:
generating a third metadata tag corresponding with a particular pattern of bits stored in the new data object,
associating the third metadata tag with a first data object identifier of the new data object, and
storing the third metadata tag and the first data object identifier in a record of the data duplication database.

9. The method of claim 8 , wherein the data duplication database is updated by scanning the storage system.

10. The method of claim 7 , wherein the data duplication database includes records of data objects having parity information.

11. A computer-implemented method for reconstructing data stored on a failed storage device of a redundant array of independent disks (RAID) type storage system having two or more storage devices, comprising:
generating a data duplication database storing both data object identifiers to identify data objects stored on the storage system and metadata tags corresponding with particular patterns of bits stored in the data objects, wherein the data duplication database is generated by,
generating a first metadata tag corresponding with a particular pattern of bits stored in a first data object stored on the storage system by applying a hash function to the first data object,
associating the first metadata tag with a first data object identifier of the first data object, and
storing the first metadata tag and the first data object identifier in a record of the data duplication database;

determining that a second data object stored on a first storage device requires reconstruction on a second storage device, wherein the first storage device is determined to inaccurately store at least one unit of data and the second storage device is designated to replace the first storage device;
determining whether a third data object used to reconstruct the second data object is corrupt;
determining, in response to determining that the third data object used to reconstruct the second data object is corrupt, whether there is a fourth data object having identical data as the third data object stored on a different storage device than the first storage device by,
retrieving a second metadata tag corresponding to the third data object from the data duplication database,
retrieving a third metadata tag corresponding to the fourth data object, and
determining whether the second metadata tag is identical to the third metadata tag; and

reconstructing, in response to determining that the second metadata tag is identical to the third metadata tag, the second data object using the fourth data object and storing the reconstructed second data object on the second storage device.

12. The method of claim 11 , further comprising:
reconstructing, in response to determining that the third data object used to reconstruct the second data object is not corrupt, the second data object according to existing RAID techniques; and
storing the reconstructed second data object on the second stor

Assignees

• IBM

Inventors

• Diederich Michael
• Muehge Thorsten
• Rueger Erik
• Wolafka Rainer

Classifications

• G06F11/1471 Primary

  involving logging of persistent data for recovery · CPC title

• G06F11/2056

  by mirroring · CPC title

• G06F3/0619

  in relation to data integrity, e.g. data losses, bit errors · CPC title

• G06F3/0689

  Disk arrays, e.g. RAID, JBOD · CPC title

• G06F11/1402

  Saving, restoring, recovering or retrying · CPC title