Extension of write anywhere file layout write allocation

• US 20050246382A1
• Filed: 04/30/2004
• Published: 11/03/2005
• Est. Priority Date: 04/30/2004
• Status: Active Grant

• Current Assignee: NetApp, Inc.
• Original Assignee: NetApp, Inc.
• Inventors: Edwards, John K.
• Granted Patent: US 7,430,571 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/13 File access structures, e.g. distributed indices arrangements of input from, or output to, record carriers G06F3/06
• CPC Class Codes: G06F 16/188 Virtual file systems
• CPC Class Codes: G06F 3/0604 Improving or facilitating administration, e.g. storage management
• CPC Class Codes: G06F 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0631 by allocating resources to storage systems
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD
• CPC Class Codes: Y10S 707/99943 Generating database or data structure, e.g. via user interface
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users
• CPC Class Codes: Y10S 707/99953 Recoverability
• CPC Class Codes: Y10S 707/99956 File allocation

Abstract

A write allocation technique extends a conventional write allocation procedure employed by a write anywhere file system of a storage system. A write allocator of the file system implements the extended write allocation technique in response to an event in the file system. The extended write allocation technique efficiently allocates blocks, and frees blocks, to and from a virtual volume (vvol) of an aggregate. The aggregate is a physical volume comprising one or more groups of disks, such as RAID groups, underlying one or more vvols of the storage system. The aggregate has its own physical volume block number (pvbn) space and maintains metadata, such as block allocation structures, within that pvbn space. Each vvol also has its own virtual volume block number (vvbn) space and maintains metadata, such as block allocation structures, within that vvbn space. The inventive technique extends input/output efficiencies of the conventional write allocation procedure to comport with an extended file system layout of the storage system.

Claims

1. A method for performing write allocation in a storage system, the method comprising the steps of:

allocating a first block to a virtual volume (vvol) from an aggregate in the storage system, wherein block allocation is performed in parallel on the vvol and the aggregate; and

freeing a second block from the vvol to the aggregate.

2. The method of claim 1 wherein the step of allocating comprises the steps of:

selecting a physical volume block number (pvbn) for the first block from a pvbn space of the aggregate and a virtual volume block number (vvbn) for the first block from a vvbn space of the vvol;

adjusting block allocation bitmap structures of the aggregate to record the selected pvbn and block allocation bitmap structures of the vvol to record the selected vvbn;

inserting the selected vvbn and a virtual volume identifier (vvid) of the vvol into an owner map of the aggregate at an entry defined by the selected pvbn;

inserting the selected pvbn into a container map of the vvol; and

updating an indirect block or inode file parent of the first block with one or more block pointers to the first block.

3. The method of claim 2 wherein the step of updating comprises the steps of:

determining whether the vvol is embodied as a hybrid vvol;

if the vvol is a hybrid vvol, inserting the selected pvbn into the indirect block or inode as the block pointer; and

if the vvol is a dual vbn hybrid vvol, inserting both the selected pvbn and the selected vvbn in the indirect block or inode as block pointers.

4. The method of claim 2 wherein the step of freeing comprises the steps of:

determining whether the vvol is embodied as a hybrid vvol;

if the vvol is a hybrid vvol, acquiring a vvbn of the second block from the owner map of the aggregate; and

if the vvol is a dual vbn hybrid vvol, acquiring the vvbn of the second block directly from an indirect block or inode of the second block.

5. The method of claim 4 wherein the block allocation bitmap structures of the aggregate and the vvol include an active map, a summary map and a space map.

6. The method of claim 5 wherein the step of freeing further comprises the steps of:

clearing a bit entry of the vvol active map for the acquired vvbn;

checking a bit entry of the vvol summary map for the acquired vvbn; and

if the bit entry is not cleared in the vvol summary map, retaining the acquired vvbn at a container file of the vvol.

7. The method of claim 6 wherein the step of freeing further comprises the steps of:

if the bit entry is cleared in the vvol summary map, decrementing the vvol space map; and

clearing a pvbn of the second block from the container map of vvol to thereby free the second block from the vvol.

8. The method of claim 7 wherein the step of freeing further comprises the steps of:

clearing a bit entry of the aggregate active map for the cleared pvbn;

checking a bit entry of the aggregate summary map for the cleared pvbn; and

if the bit entry is cleared, decrementing the aggregate space map.

9. The method of claim 6 wherein the step of freeing further comprises the step of, if the bit entry is cleared in the vvol summary map, delaying release of the second block from the vvol to the aggregate.

10. A system adapted to perform write allocation in a storage system having a plurality of disks, the system comprising:

a file system executing on the storage system, the file system adapted to logically organize information stored on the disks as a physical volume block number (pvbn) space and a virtual volume block number (vvbn) space;

an aggregate including one or more groups of disks adapted to utilize the pvbn space to define a storage space of blocks provided by the disks;

at least one virtual volume (vvol) contained within the aggregate, the vvol adapted to utilize the vvbn space to organize the blocks within files;

block allocation bitmap structures configured to provide disk geometry information, the block allocation bitmap structures maintained by the file system for the aggregate and the vvol; and

a write allocator of the file system configured to allocate a first block to the vvol from the aggregate and free a second block from the vvol to the aggregate.

11. The system of claim 10 wherein the block allocation bitmap structures of the aggregate and the vvol include an active map, a summary map and a space map.

12. The system of claim 11 wherein the write allocator allocates the first block to the vvol by implementing a write allocation technique that (i) selects a pvbn for the block from the pvbn space of the aggregate and a vvbn for the block from a vvbn space of the vvol and (ii) adjusts the block allocation bitmap structures of the aggregate to record the selected pvbn and block allocation bitmap structures of the vvol to record the selected vvbn.

13. The system of claim 12 further comprising an owner map of the aggregate that provides a backward mapping between the selected pvbn in the aggregate to a virtual volume identifier (vvid) that owns the selected pvbn and the selected vvbn of the vvol in which the pvbn is located.

14. The system of claim 13 wherein the write allocator allocates the first block to the vvol by implementing the write allocation technique that further inserts the selected vvbn and vvid of the vvol into the owner map at an entry defined by the selected pvbn.

15. The system of claim 14 further comprising a container map of the vvol that provides a forward mapping of the selected vvbn of the vvol to the selected pvbn of the aggregate.

16. The system of claim 15 wherein the write allocator allocates the first block to the vvol by implementing the write allocation technique that further inserts the selected pvbn into the container map of the vvol.

17. The system of claim 16 further comprising a buffer tree configured to provide a representation of blocks for a file in a memory of the storage system.

18. The system of claim 17 wherein the write allocator allocates the first block to the vvol by implementing a write allocation technique that further updates an indirect block or inode file parent of the first block in the buffer tree with one or more block pointers to the block.

19. Apparatus for performing write allocation in a storage system, the apparatus comprising:

means for allocating a first block to a virtual volume (vvol) from an aggregate in the storage system; and

means for freeing a second block from the vvol to the aggregate.

20. A computer readable medium containing executable program instructions for performing write allocation in a storage system, the executable instructions comprising one or more program instructions for:

allocating a first block to a virtual volume (vvol) from an aggregate in the storage system; and

freeing a second block from the vvol to the aggregate.