SYSTEM AND METHOD FOR RAID MANAGEMENT, REALLOCATION, AND RESTRIPPING

• US 20110167219A1
• Filed: 02/07/2011
• Published: 07/07/2011
• Est. Priority Date: 05/24/2006
• Status: Active Grant

• Current Assignee: Dell International LLC (Dell Technologies Inc.)
• Original Assignee: Compellent Technologies Incorporated (Dell Technologies Inc.)
• Inventors: Uttormark, Michael J., Klemm, Michael J.
• Granted Patent: US 8,230,193 B2
• Time in Patent Office: Days
• US Class Current: 711/114
• 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 3/0607 by facilitating the process of upgrading existing storage systems, e.g. for improving compatibility between host and storage device
• 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 3/0632 by initialisation or re-initialisation of storage systems
• CPC Class Codes: G06F 3/0647 Migration mechanisms
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD

Abstract

The present disclosure relates to systems and methods for RAID Restriping. One method includes selecting an initial RAID device for migration based on at least one score, creating an alternate RAID device, moving data from the initial RAID device to the alternate RAID device, and removing the initial RAID device. The method may be performed automatically by the system or manually. The method may be performed periodically, continuously, after every RAID device migration, upon addition of disk drives, and/or before removal of disk drives, etc. One system includes a RAID subsystem and a disk manager configured to automatically calculate a score for each RAID device, select a RAID device based on the relative scores of the RAID devices, create an alternate RAID device, move data from the selected RAID device to the alternate RAID device, and remove the selected RAID device.

Claims

1. A method of data migration in a disk drive system, comprising the steps of:

a. selecting a data storage device for migration based on at least one score calculated for each of a plurality of data storage devices;

b. creating at least one alternate data storage device;

c. moving data stored at the selected data storage device to the at least one alternate data storage device; and

d. removing the selected data storage device.

2. The method of claim 1, wherein the at least one score comprises an initial score and a replacement score, wherein the initial score relates to the selected data storage device and the replacement score relates to at least one first hypothetical data storage device located in available disk space.

3. The method of claim 2, wherein the at least one score further comprises an overlay score relating to at least one second hypothetical data storage device located in a combination of available disk space and the disk space taken up by the selected data storage device.

4. The method of claim 3, wherein the selected data storage device and the at least one first hypothetical data storage device are RAID devices, and wherein the initial score, replacement score, and overlay score are each calculated based on at least one of factors comprising the RAID level, RAID stripe size, RAID extent size, disk category, location on disk, disk enclosure, disk enclosure power supply, and communication path to the disk.

5. The method of claim 4, wherein the factors have varying weights for use in the calculation.

6. The method of claim 5, wherein the initial score, replacement score, and overlay score are each calculated using the same factors.

7. The method of claim 4, wherein selecting a data storage device for migration based on at least one score calculated for each of a plurality of data storage devices comprises selecting the data storage device if at least one of the replacement score or overlay score is better than the initial score.

8. The method of claim 7, wherein the alternate data storage device is based on one of the first and second hypothetical data storage devices.

9. The method of claim 1, wherein the steps of selecting a data storage device for migration, creating at least one alternate data storage RAID device, moving data, and removing the selected data storage device are done automatically without manual intervention.

10. The method of claim 9, wherein the steps are performed without loss of server data access to the disk drive system and compromised resiliency of the data.

11. The method of claim 9, wherein the steps are performed at least one of periodically, continuously, after every data storage device migration, upon addition of disk drives, and before removal of disk drives.

12. The method of claim 1, wherein the steps of selecting a data storage device for migration, creating at least one alternate data storage device, moving data, and removing the selected data storage device are done manually.

13. The method of claim 1, wherein moving data stored at the selected data storage device to the at least one alternate data storage device further comprises creating at least one temporary data storage device.

14. The method of claim 13, further comprising moving data stored at the selected data storage device to the at least one temporary data storage device and then from the temporary data storage device to the at least one alternate data storage device.

15. A disk drive system, comprising:

a. a data storage subsystem; and

b. a disk manager having at least one disk storage system controller configured to automatically;

c. calculate at least one score for each data storage device of a plurality of data storage devices of the data storage subsystem;

d. select a data storage device from the plurality of data storage devices based on the relative at least one scores of the plurality of data storage devices.

e. create an alternate data storage RAID device;

f. move at least a portion of the data stored at the selected data storage device to the alternate data storage device; and

g. remove the selected data storage device.

16. The disk drive system of claim 15, wherein the at least one score comprises an initial score for the data storage device, a replacement score related to a first hypothetical data storage device, and an overlay score related to a second hypothetical data storage device.

17. The disk drive system of claim 16, wherein the alternate data storage device is based on one of the first and second hypothetical data storage devices.

18. The disk drive system of claim 15, wherein the data storage subsystem is a RAID subsystem, and wherein the disk drive system comprises storage space from at least one of a plurality of RAID levels including RAID-0, RAID-1, RAID-5, and RAID-10.

19. The system of claim 18, further comprising RAID levels including RAID-3, RAID-4, RAID-6, and RAID-7.

20. A disk drive system capable of data migration, comprising:

a. means for selecting a data storage device for migration based on at least one score calculated for each of a plurality of data storage devices;

b. means for creating at least one alternate data storage device;

c. means for moving data stored at the selected data storage device to the at least one alternate data storage device; and

d. means for removing the selected data storage device.

21. A method for reallocating data, comprising:

a. determining a score for a current position of data and a score for an alternate position the data;

b. comparing the score for the current position of the data and the score for the alternate position of the data; and

c. moving the data from the current position to the alternate position when the score for the alternate position of the data is better than the score for the current position of the data.