Distributed multi-level protection in a raid array based storage system

• US 9,348,696 B2
• Filed: 10/01/2010
• Issued: 05/24/2016
• Est. Priority Date: 10/01/2010
• Status: Expired

• Current Assignee: Pure Storage, Inc.
• Original Assignee: Pure Storage, Inc.
• Inventors: Colgrove, John, Hayes, John, Hong, Bo, Miller, Ethan
• Primary Examiner(s): Rigol, Yaima
• Application Number:
  US12/896,675
• Publication Number:
  US 20120084506A1
• Time in Patent Office: 2,062 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 11/3034 where the computing system component is a storage system, e.g. DASD based or network based digital input from or digital output to record carriers G06F3/06; digital recording or reproducing G11B20/18; for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS], H04L67/1097
• CPC Class Codes: G06F 11/3055 Monitoring arrangements for monitoring the status of the computing system or of the computing system component, e.g. monitoring if the computing system is on, off, available, not available error or fault processing without redundancy G06F11/0703; error detection or correction by redundancy in data representation G06F11/08; error detection or correction by redundancy in operation G06F11/14; error detection or correction by redundancy in hardware G06F11/16
• CPC Class Codes: G06F 2211/1057 Parity-multiple bits-RAID6, i.e. RAID 6 implementations
• CPC Class Codes: G06F 2211/1059 Parity-single bit-RAID5, i.e. RAID 5 implementations
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]

Abstract

A system and method for dynamic RAID geometries. A computer system comprises client computers and data storage arrays coupled to one another via a network. A data storage array utilizes solid-state drives and Flash memory cells for data storage. A storage controller within a data storage array is configured to configure a first subset of the storage devices for use in a first RAID layout, the first RAID layout including a first set of redundant data. The controller further configures a second subset of the storage devices for use in a second RAID layout, the second RAID layout including a second set of redundant data. Additionally, when writing a stripe, the controller may select from any of the plurality of storage devices for one or more of the first RAID layout, the second RAID layout, and storage of redundant data by the additional logical device.

Claims

1. A computer system comprising:

a data storage subsystem comprising a plurality of storage devices in a redundant array of independent disks (RAID) configuration; and

a storage controller configured to;

write a first RAID stripe to the plurality of storage devices including;

for each storage device of a subset of the plurality of storage devices, writing within a page of the storage device, user data and a checksum that validates the user data stored on the storage device;

writing within a page of a particular storage device of the plurality storage devices,

inter-device protection data, the inter-device protection data protecting the user data stored on each storage device of the subset of the plurality of storage devices;

intra-page protection data, the intra-page protection data protecting the inter-device protection data stored on the particular storage device; and

inter-page protection data, the inter-page protection data protecting the checksums stored on each storage device of the subset of storage devices.

2. The computer system as recited in claim 1, wherein the storage controller is further configured to write a second RAID stripe to a subset of the plurality of storage devices, the first RAID stripe having a first RAID layout and the second RAID stripe having a second RAID layout.

3. The computer system as recited in claim 2, wherein the first RAID layout is an L+x layout, and the second RAID layout is an M+y layout, wherein L, x, M, and, y are integers, and wherein either or both (1) L is not equal to M, and (2) x is not equal to y.

4. The computer system as recited in claim 2, wherein the first RAID layout is selected from a first device group and the second RAID layout is selected from a second device group.

5. The computer system as recited in claim 2, wherein the first RAID layout and the second RAID layout include at least one device that has a larger storage capacity than other devices included in the first RAID layout and the second RAID layout.

6. The computer system as recited in claim 2, wherein the storage controller is further configured to configure an additional logical device not included in either the first RAID layout or the second RAID layout to store redundant data for both the first RAID layout and the second RAID layout.

7. The computer system as recited in claim 1, wherein the plurality of storage devices are solid state storage devices.

8. The computer system as recited in claim 1, wherein the storage controller is configured to store metadata, user data, and protection data in pages, each page including a header with a checksum.

9. A method for use in a computing system, the method comprising:

writing a RAID stripe to a plurality of storage devices in a redundant array of independent disks (RAID) configuration, wherein writing the RAID stripe includes;

for each storage device of a subset of the plurality of storage devices, writing within a page of the storage device, user data and a checksum that validates the user data stored on the storage device;

writing within a page of a particular storage device of the plurality storage devices,

inter-device protection data, the inter-device protection data protecting the user data stored on each storage device of the subset of the plurality of storage devices;

intra-page protection data, the intra-page protection data protecting the inter-device protection data stored on the particular storage device; and

inter-page protection data, the inter-page protection data protecting the checksums stored on each storage device of the subset of storage devices.

10. The method as recited in claim 9, further comprising writing a second RAID stripe to a subset of the plurality of storage devices, the first RAID stripe having a first RAID layout and the second RAID stripe having a second RAID layout.

11. The method as recited in claim 10, wherein the first RAID layout is an L+x layout, and the second RAID layout is an M+y layout, wherein L, x, M, and, y are integers, and wherein either or both (1) L is not equal to M, and (2) x is not equal to y.

12. The method as recited in claim 10, wherein the first RAID layout is selected from a first device group, and the second RAID layout is selected from a second device group.

13. The method as recited in claim 9, wherein the plurality of storage devices are solid state storage devices.

14. The method as recited in claim 9, further comprising storing metadata, user data, and protection data in pages, each page including a header with a checksum.

15. A non-transitory computer readable storage medium storing program instructions, wherein the program instructions are executable to:

write a RAID stripe to a plurality of storage devices in a redundant array of independent disks (RAID) configuration, wherein writing the RAID stripe includes;

for each storage device of a subset of the plurality of storage devices, writing within a page of the storage device, user data and a checksum that validates the user data stored on the storage device;

writing within a page of a particular storage device of the plurality storage devices,

inter-device protection data, the inter-device protection data protecting the user data stored on each storage device of the subset of the plurality of storage devices;

intra-page protection data, the intra-page protection data protecting the inter-device protection data stored on the particular storage device; and

inter-page protection data, the inter-page protection data protecting the checksums stored on each storage device of the subset of storage devices.

16. The non-transitory computer readable storage medium as recited in claim 15, wherein the storage controller is further configured to write a second RAID stripe to a subset of the plurality of storage devices, the first RAID stripe having a first RAID layout and the second RAID stripe having a second RAID layout.

17. The non-transitory computer readable storage medium as recited in claim 16, wherein the first RAID layout is an L+x layout, and the second RAID layout is an M+y layout, wherein L, x, M, and, y are integers, and wherein either or both (1) L is not equal to M, and (2) x is not equal to y.

18. The non-transitory computer readable storage medium as recited in claim 15, wherein the plurality of storage devices are solid state storage devices.