File system driven raid rebuild technique

• US 10,013,311 B2
• Filed: 05/27/2016
• Issued: 07/03/2018
• Est. Priority Date: 01/17/2014
• Status: Active Grant

• Current Assignee: NetApp, Inc.
• Original Assignee: NetApp, Inc.
• Inventors: Sundaram, Rajesh, Baddepudi, Bharat, Kimmel, Jeffrey S., Rakitzis, T. Byron
• Primary Examiner(s): Contino, Paul
• Application Number:
  US15/166,600
• Publication Number:
  US 20160274973A1
• Time in Patent Office: 767 Days
• CPC Class Codes: G06F 11/1008 in individual solid state devices G06F11/1004 takes precedence
• CPC Class Codes: G06F 11/1068 in sector programmable memories, e.g. flash disk G06F11/1072 takes precedence
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 11/108 Parity data distribution in semiconductor storages, e.g. in SSD
• CPC Class Codes: G06F 11/1084 Degraded mode, e.g. caused by single or multiple storage removals or disk failures
• CPC Class Codes: G06F 11/1092 Rebuilding, e.g. when physically replacing a failing disk
• CPC Class Codes: G06F 11/1096 Parity calculation or recalculation after configuration or reconfiguration of the system
• CPC Class Codes: G06F 16/1847 specifically adapted to static storage, e.g. adapted to flash memory or SSD
• CPC Class Codes: G06F 2211/1057 Parity-multiple bits-RAID6, i.e. RAID 6 implementations
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/0653 Monitoring storage devices or systems
• CPC Class Codes: G06F 3/0688 Non-volatile semiconductor memory arrays
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD
• CPC Class Codes: G11C 29/52 Protection of memory contents; Detection of errors in memory contents

Abstract

Embodiments described herein are directed to a file system driven RAID rebuild technique. A layered file system may organize storage of data as segments spanning one or more sets of storage devices, such as solid state drives (SSDs), of a storage array, wherein each set of SSDs may form a RAID group configured to provide data redundancy for a segment. The file system may then drive (i.e., initiate) rebuild of a RAID configuration of the SSDs on a segment-by-segment basis in response to cleaning of the segment (i.e., segment cleaning). Each segment may include one or more RAID stripes that provide a level of data redundancy (e.g., single parity RAID 5 or double parity RAID 6) as well as RAID organization (i.e., distribution of data and parity) for the segment. Notably, the level of data redundancy and RAID organization may differ among the segments of the array.

Claims

1. A system comprising:

a central processing unit (CPU) of a node;

one or more storage arrays of solid state drives (SSDs) coupled to the node, each storage array including a plurality of segments, the SSDs organized as one or more redundant array of independent disks (RAID) groups configured to provide data redundancy for the segments; and

a memory coupled to the CPU and configured to store a layered file system of a storage input/output (I/O) stack executing on the CPU, the layered file system configured to initiate rebuild of a RAID configuration of the SSDs on a segment-by-segment basis in response to segment cleaning when a SSD fails, wherein the rebuild accelerates when a reserve space in the SSDs falls below a threshold in response to removal of a storage capacity of the failed SSD from the reserve space.

2. The system of claim 1 wherein the rebuild of the RAID configuration maintains a reserve space level in the SSDs.

3. The system of claim 1 wherein a frequency of the segment cleaning and a selection of segments to clean are based on a level of reserve space in the segments.

4. The system of claim 1 wherein the rebuild of the RAID configuration occurs in response to a file system operation of the segment cleaning.

5. The system of claim 1 wherein the segment cleaning is initiated based on the segments having a most available free space.

6. The system of claim 1 wherein each segment includes one or more RAID stripes that provide a level of redundancy for the segment.

7. The system of claim 6 wherein the level of redundancy includes one of single parity RAID 5 and double parity RAID 6.

8. A method comprising:

organizing one or more storage arrays of solid state drives (SSDs) that include a plurality of segments as one or more redundant array of independent disks (RAID) groups, the RAID groups configured to provide data redundancy for the segments;

initiating, by a processor of a node executing a layered file system of a storage input/output stack, rebuild of a RAID configuration of the SSDs on a segment-by-segment basis in response to segment cleaning when a SSD fails; and

accelerating the rebuild of the RAID configuration when a reserve space in the SSDs falls below a threshold in response to removal of a storage capacity of the failed SSD from the reserve space.

9. The method of claim 8 wherein the rebuild of the RAID configuration maintains a reserve space level in the SSDs.

10. The method of claim 8 wherein a frequency of the segment cleaning and a selection of segments to clean are based on a level of reserve space in the segments.

11. The method of claim 8 wherein the rebuild of the RAID configuration occurs in response to a file system operation of the segment cleaning.

12. The method of claim 8 wherein the segment cleaning is initiated based on the segments having a most available free space.

13. The method of claim 8 wherein each segment includes one or more RAID stripes that provide a level of redundancy for the segment.

14. The method of claim 13 wherein the level of redundancy includes one of single parity RAID 5 and double parity RAID 6.

15. A non-transitory computer readable medium including program instructions for execution on one or more processors, the program instructions configured to:

organize one or more storage arrays of solid state drives (SSDs) that include a plurality of segments as one or more redundant array of independent disks (RAID) groups, the RAID groups configured to provide data redundancy for the segments;

initiate rebuild of a RAID configuration of the SSDs on a segment-by-segment basis in response to segment cleaning when a SSD fails; and

accelerate the rebuild of the RAID configuration when a reserve space in the SSDs falls below a threshold in response to removal of a storage capacity of the failed SSD from the reserve space.

16. The non-transitory computer readable medium of claim 15 wherein the rebuild of the RAID configuration maintains a reserve space level in the SSDs.

17. The non-transitory computer readable medium of claim 15 wherein a frequency of the segment cleaning and a selection of segments to clean are based on a level of reserve space in the segments.

18. The non-transitory computer readable medium of claim 15 wherein the rebuild of the RAID configuration occurs in response to a file system operation of the segment cleaning.

19. The non-transitory computer readable medium of claim 15 wherein the segment cleaning is initiated based on the segments having a most available free space.

20. The non-transitory computer readable medium of claim 15 wherein each segment includes one or more RAID stripes that provide a level of redundancy for the segment.