Location-independent RAID group virtual block management

• US 7,111,147 B1
• Filed: 03/21/2003
• Issued: 09/19/2006
• Est. Priority Date: 03/21/2003
• Status: Active Grant

• Current Assignee: NetApp, Inc.
• Original Assignee: Network Appliance Incorporated (NetApp, Inc.)
• Inventors: Schoenthal, Scott, Doucette, Douglas P., Viswanathan, Srinivasan, Strange, Stephen H.
• Primary Examiner(s): PORTKA, GARY J
• Application Number:
  US10/394,890
• Time in Patent Office: 1,278 Days
• Field of Search: None
• US Class Current: 711/209
• CPC Class Codes: G06F 11/1092 Rebuilding, e.g. when physically replacing a failing disk
• CPC Class Codes: G06F 11/2056 by mirroring
• CPC Class Codes: G06F 2211/1023 Different size disks, i.e. non uniform size of disks in RAID systems with parity
• 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 3/0643 Management of files
• CPC Class Codes: G06F 3/0647 Migration mechanisms
• CPC Class Codes: G06F 3/0665 at area level, e.g. provisioning of virtual or logical volumes
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD
• 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 technique maps the capacity of storage devices, such as disks, into any RAID group of a volume of a storage system regardless of the location of the RAID group within a volume block number (VBN) space of the volume. The technique separates disks and mapped VBN ranges, allowing for flexibility in the description and extension of RAID group capacities, while providing disk addition policies that support location-independent disk insertion into RAID groups. The technique also provides a disk label structure that supports the provision of multiple VBN ranges within a RAID group and within individual disks. Moreover, the technique provides file system support for allocation and topology management of the multiple mapped VBN ranges within disks and RAID groups, as well as noncontiguous VBN ranges across the RAID groups in the volume.

Claims

1. A system configured to map a capacity of storage devices into any RAID group of a volume of a storage system, the storage devices organized as one or more RAID groups, the storage devices further cooperating to define an arrangement of volume block number (VBN) space on the volume, the system comprising:

a RAID subsystem of the storage system, the RAID subsystem managing storage and retrieval of information to and from the volume;

one or more raidmap structures used to map one or more VBN ranges of the VBN space of the volume into a disk block number (DBN) space of each storage device, the raidmap maintained by the RAID subsystem and comprising mapping parameters that enable mapping to selected DBN ranges of the DBN space on each storage device from VBN ranges of the volume, the raidmap configured to accept mapping parameters to establish different range lengths for different DBN ranges; and

a disk label structure on each storage device, the disk label structure adapted to store one or more raidmap structure on each storage device.

2. The system of claim 1 wherein the mapping parameters comprise a base offset into a VBN range of the volume, a base offset into a DBN range of the storage device and a size of DBN-to-VBN mapping.

3. The system of claim 2 further comprising a write allocator of the storage system, the write allocator adapted to use the mapping parameters of the raidmap to determine noncontiguous VBN-to-DBN mapping of a storage device within a RAID group.

4. The system of claim 3 further comprising a topology mechanism adapted to export the raidmap from the RAID subsystem to the write allocator.

5. The system of claim 4 wherein the topology mechanism is a raidmap cache.

6. The system of claim 5 wherein the storage devices are disks.

7. A method for replacing a failed disk with a larger disk and mapping a capacity of the larger disk into a RAID group of a volume of a storage system, the volume having a volume block number (VBN) space, the method comprising the steps of:

creating a first raidmap to reconstruct the failed disk using a first portion of the larger disk;

creating a second raidmap to map a second portion of the larger disk into the VBN space of the volume to thereby extend a VBN range of the VBN space and allow use of the second portion by the system; and

storing the first and second raidmaps in a RAID label on the larger disk.

8. The method of claim 7 wherein the step of creating further comprises the step of using the raidmap to map a VBN range of the VBN space of the volume into a disk block number (DBN) space of the larger disk, the raidmap comprising mapping parameters that enable separation of DBN ranges of the DBN space on the larger disk from VBN ranges of the volume.

9. The method of claim 8 further comprising the step of providing a RAID subsystem of the storage system, the RAID subsystem managing storage and retrieval of information, including the mapping parameters of the raidmap, to and from the volume.

10. The method of claim 9 further comprising the step of exporting the mapping parameters of the raidmap from the RAID subsystem to a write allocator of the storage system, the write allocator using the mapping parameters to determine noncontiguous VBN-to-DBN mapping of the larger disk within the RAID group.

11. A method for mapping a capacity of disks into a volume of a storage system, the method comprising the steps of:

organizing the disks as one or more RAID groups, the disks cooperating to define an arrangement of volume block number (VBN) space on the volume;

managing storage and retrieval of information to and from the volume using a RAID subsystem of the storage system;

mapping one or more VBN ranges of the VBN space of the volume into a disk block number (DBN) space of each disk using one or more raidmaps, each raidmap maintained by the RAID subsystem and comprising mapping parameters that enable mapping to selected DBN ranges of the DBN space on each disk from VBN ranges of the volume, the raidmap configured to accept mapping parameters to establish different range lengths for different DBN ranges; and

storing at least one raidmap in a RAID label on each disk.

12. Apparatus configured to map a capacity of storage device into a storage system having a plurality of volumes, each volume including a collection of storage devices cooperating to define an overall logical arrangement of volume block number (VBN) space on the volume, the apparatus comprising:

a raidmap used to map one or more VBN ranges of the VBN spaces of the volumes into a disk block number (DBN) space of the storage device; and

a disk label on the storage device, the disk label adapted to store more than one raidmap to thereby enable a first portion of the DBN space of the storage device to reside in a first volume and a second portion of the DBN space of the storage device to reside in a second volume.

13. The apparatus of claim 12 wherein each raidmap comprises mapping parameters that enable separation of DBN ranges of the DBN space on the storage device from VBN ranges of the volume.

14. The apparatus of claim 13 wherein the mapping parameters comprise a base offset into a VBN range of the volume, a base offset into a DBN range of the storage device and a size of DBN-to-VBN mapping.

15. The apparatus of claim 12 wherein the first and second volumes are a same volume.

16. The apparatus of claim 12 wherein the first and second volumes are different volumes.

17. The apparatus of claim 12 wherein the storage devices are disks.

18. A computer readable medium containing executable program instructions for replacing a failed disk with a larger disk and mapping a capacity of the larger disk into a RAID group of a volume of a storage system, the volume having a volume block number (VBN) space, the executable instructions comprising one or more program instructions for:

creating a first raidmap to reconstruct the failed disk using a first portion of the larger disk;

creating a second raidmap to map a second portion of the larger disk into the VBN space of the volume; and

storing the first and second raidmaps in a RAID label on the larger disk.

19. The computer readable medium of claim 18 wherein the one or more program instructions for creating further comprises one or more program instructions for using the raidmap to map a VBN range of the VBN space of the volume into a disk block number (DBN) space of the larger disk, the raidmap comprising mapping parameters that enable separation of DBN ranges of the DBN space on the larger disk from VBN ranges of the volume.

20. Apparatus for mapping a capacity of disks into a volume of a storage system, the apparatus comprising:

means for organizing the disks as one or more RAID groups, the disks cooperating to define an arrangement of volume block number (VBN) space on the volume;

means for managing storage and retrieval of information to and from the volume using a RAID subsystem of the storage system;

means for mapping one or more VBN ranges of the VBN space of the volume into a disk block number (DBN) space of each disk using one or more raidmaps, each raidmap maintained by the RAID subsystem and comprising mapping parameters that enable mapping to selected DBN ranges of the DBN space on each disk from VBN ranges of the volume, the raidmap configured to accept mapping parameters to establish different range lengths for different DBN ranges; and

means for storing at least one raidmap in a RAID label on each disk.