File system driven raid rebuild technique

• US 9,454,434 B2
• Filed: 01/17/2014
• Issued: 09/27/2016
• 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): Chu, Gabriel
• Assistant Examiner(s): CONTINO, PAUL F
• Application Number:
  US14/158,448
• Publication Number:
  US 20150205668A1
• Time in Patent Office: 984 Days
• US Class Current: 1/1
• 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

In one embodiment, one or more storage arrays of solid state drives (SSDs) that include a plurality of segments are organized as one or more redundant array of independent disks (RAID) groups, where the RAID groups provides data redundancy for the segments. A node executing a layered file system of a storage input/output (I/O) stack performs segment cleaning to clean the segments. It further initiates rebuild of a RAID configuration of the SSDs on a segment-by-segment basis in response to the segment cleaning. In such a configuration, each segment includes one or more RAID stripes that provide a level of data redundancy as well as RAID organization for the segment.

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, the layered file system configured to perform segment cleaning to consolidate fragmented free space of a first segment by copying data from the first segment to a second segment, the layered file system further configured to initiate the segment cleaning of the first segment having a RAID configuration including a temporarily failed SSD in response to recovery of the temporarily failed SSD, wherein the RAID configuration is rebuilt for the second segment in response to the segment cleaning of the first segment, and wherein data in-flight to the temporarily failed SSD is discarded while the temporarily failed SSD is offline rather than rewritten when the temporarily failed SSD recovers.

2. The system of claim 1 wherein each segment includes one or more RAID stripes configured to provide a level of data redundancy as well as RAID organization for the segment, and wherein the level of data redundancy and the RAID organization differ among the segments.

3. The system of claim 2 wherein the level of data redundancy includes one of single parity RAID 5 and double parity RAID 6.

4. The system of claim 2 wherein the RAID organization comprises distribution of data and parity among the SSDs of the segment.

5. The system of claim 4 wherein the distribution of the parity includes different parity locations on the SSDs for different segments.

6. The system of claim 4 wherein the distribution of the parity includes a first set of fixed parity SSDs for the first segment and a second set of fixed parity SSDs for the second segment different from the first segment, and wherein the first set of fixed parity SSDs is different from the second set of fixed parity SSDs.

7. The system of claim 4 wherein the distribution of parity is realized on a segment-by-segment basis with a fixed parity arrangement within each segment.

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;

performing, by a node executing a layered file system of a storage input/output (I/O) stack, segment cleaning to consilidatc fragmented free space of a first segment by copying data from the first segment to a second segment; and

initiating the segment cleaning of the first segment having a RAID configuration including a temporarily failed SSD in response to recovery of the temporarily failed SSD,

wherein the RAID configuration is rebuilt for the second segment in response to the segment cleaning of the first segment, and wherein data in-flight to the temporarily failed SSD is discarded while the temporarily failed SSD is offline rather than rewritten when the temporarily failed SSD recovers.

9. The method of claim 8 wherein each segment includes one or more RAID stripes configured to provide a level of data redundancy as well as RAID organization for the segment, and wherein the level of data redundancy and the RAID organization differ among the segments.

10. The method of claim 9 wherein the level of data redundancy includes one of single parity RAID 5 and double parity RAID 6.

11. The method of claim 9 further comprising:

distributing data and parity among the SSDs of the segment as part of the RAID configuration.

12. The method of claim 11 wherein the distributing data and parity further comprises:

using different parity locations on the SSDs for different segments.

13. The method of claim 11 wherein the distributing data and parity further comprises:

using a first set of fixed parity SSDs for the first segment and a second set of fixed parity SSDs for the second segment different from the first segment, wherein the first set of fixed parity SSDs is different from the second set of fixed parity SSDs.

14. The method of claim 8 wherein the distributing data and parity is performed on a segment-by-segment basis with a fixed parity arrangement within each segment.

15. A non-transitory computer readable medium including program instructions for execution on one or more processors, the program instructions when executed operable 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;

perform segment cleaning to consolidate fragmented free space of a first segment by copying data from the first segment to a second segment; and

initiate the segment cleaning of the first segment having a RAID configuration including a temporarily failed SSD in response to recovery of the temporarily failed SSD,

wherein the RAID configuration is rebuilt for the second segment in response to the segment cleaning of the first segment, and wherein data in-flight to the temporarily failed SSD is discarded while the temporarily failed SSD is offline rather than rewritten when the temporarily failed SSD recovers.

16. The non-transitory computer readable medium of claim 15 wherein each segment includes one or more RAID stripes configured to provide a level of data redundancy as well as RAID organization for the segment, and wherein the level of data redundancy and the RAID organization differ among the segments.

17. The non-transitory computer readable medium of claim 16 wherein the level of data redundancy includes one of single parity RAID 5 and double parity RAID 6.

18. The non-transitory computer readable medium of claim 16 wherein the RAID organization comprises distribution of data and parity among the SSDs of the segment.

19. The non-transitory computer readable medium of claim 18 wherein the distribution of the parity includes different parity locations on the SSDs for different segments.

20. The non-transitory computer readable medium of claim 18 wherein the distribution of the parity includes a first set of fixed parity SSDs for the first segment and a second set of fixed parity SSDs for the second segment different from the first segment, wherein the first set of fixed parity SSDs is different from the second set of fixed parity SSDs.