MANAGEMENT OF RECYCLING BIN FOR THINLY-PROVISIONED LOGICAL VOLUMES

• US 20100042802A1
• Filed: 08/15/2008
• Published: 02/18/2010
• Est. Priority Date: 08/15/2008
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Schwarz, Shemer, Helman, Haim, Sandler, Kariel Eliahu
• Granted Patent: US 8,347,059 B2
• Time in Patent Office: Days
• US Class Current: 711/173
• CPC Class Codes: G06F 12/0646 Configuration or reconfiguration
• CPC Class Codes: G06F 3/0605 by facilitating the interaction with a user or administrator
• CPC Class Codes: G06F 3/0631 by allocating resources to storage systems
• CPC Class Codes: G06F 3/0665 at area level, e.g. provisioning of virtual or logical volumes
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]

Abstract

A method for data storage includes representing logical volumes by respective sets of pointers to physical partitions in which data used by the logical volumes is stored. One or more of the logical volumes are defined as provisionally deleted. A subset of the provisionally-deleted logical volumes is selected such that each logical volume in the subset has one or more private physical partitions whose data is used exclusively by that logical volume. One or more of the private physical partitions of the logical volumes in the subset are released for reallocation to another logical volume.

Claims

1. A method for data storage, comprising:

representing logical volumes by respective sets of pointers to physical partitions in which data used by the logical volumes is stored;

defining one or more of the logical volumes as provisionally deleted;

selecting a subset of the provisionally-deleted logical volumes such that each logical volume in the subset has one or more private physical partitions whose data is used exclusively by that logical volume; and

releasing one or more of the private physical partitions of the logical volumes in the subset for reallocation to another logical volume.

2. The method according to claim 1, wherein at least one of the logical volumes in the subset comprises a copy of a given logical volume.

3. The method according to claim 1, wherein releasing the private physical partitions comprises permanently deleting the logical volumes in the subset.

4. The method according to claim 3, wherein representing the logical volumes comprises defining a reference-count list indicating respective counts of the logical volumes that point to the physical partitions, and wherein permanently deleting the logical volumes in the subset comprises updating the reference-count list.

5. The method according to claim 1, wherein selecting the subset comprises selecting the provisionally-deleted logical volumes having oldest provisional deletion times.

6. The method according to claim 1, wherein selecting the subset comprises selecting the provisionally-deleted logical volumes having highest numbers of the private physical partitions.

7. The method according to claim 1, wherein representing the logical volumes comprises representing the logical volumes by a hierarchical tree structure comprising nodes, wherein each of the nodes comprises a respective set of local pointers, and wherein the logical volumes are represented by respective nodes such that the local pointers in the nodes located along a path via the tree structure that connects a given node to a root node of the tree structure point to the physical partitions in which the data used by the logical volume represented by the given node is stored.

8. The method according to claim 7, wherein the local pointers in each node point to the private physical partitions of that node, and wherein selecting the subset comprises identifying the nodes having non-empty sets of the local pointers as representing the logical volumes having the private partitions.

9. The method according to claim 7, wherein releasing the private physical partitions comprises permanently deleting the logical volumes in the subset by deleting the nodes representing the logical volumes in the subset from the tree structure.

10. The method according to claim 9, wherein the tree structure comprises a binary tree in which the logical volumes are represented by leaf nodes and in which nodes that connect the leaf nodes to the root node comprise artificial nodes, and wherein deleting a first leaf node, which represents a first logical volume and is located below an artificial node, comprises:

deleting from the tree structure a second leaf node that represents a second logical volume and is located below the artificial node;

converting the artificial node into a merged node representing the second logical volume; and

combining the local pointers of the second leaf node with the local pointers of the artificial node to produce the local pointers of the merged node.

11. The method according to claim 1, and comprising accepting a request to allocate at least one physical partition to the other logical volume, and selecting the subset and releasing the private physical partitions responsively to the request.

12. The method according to claim 11, wherein the request comprises an instruction to create the other logical volume.

13. The method according to claim 11, wherein the request comprises an instruction to resize the other logical volume.

14. The method according to claim 11, wherein the data used by the other logical volume is stored on a first storage device, and wherein the request comprises an instruction to allocate the at least one physical partition to the other logical volume on a second storage device upon a failure in the first storage device.

15. Apparatus for data storage, comprising:

an interface, which is operative to communicate with at least one host computer so as to receive data for storage that is addressed to logical volumes assigned on a storage device having physical partitions; and

a processor, which is coupled to represent the logical volumes by respective sets of pointers to the physical partitions in which data used by the logical volumes is stored, to define one or more of the logical volumes as provisionally deleted, to select a subset of the provisionally-deleted logical volumes such that each logical volume in the subset has one or more private physical partitions whose data is used exclusively by that logical volume, and to release one or more of the private physical partitions of the logical volumes in the subset for reallocation to another logical volume.

16. The apparatus according to claim 15, wherein at least one of the logical volumes in the subset comprises a copy of a given logical volume.

17. The apparatus according to claim 15, wherein the processor is coupled to permanently delete the logical volumes in the subset.

18. The apparatus according to claim 15, wherein the processor is coupled to select the provisionally-deleted logical volumes having oldest provisional deletion times.

19. The apparatus according to claim 15, wherein the processor is coupled to select the provisionally-deleted logical volumes having highest numbers of the private physical partitions.

20. The apparatus according to claim 15, wherein the processor is coupled to represent the logical volumes by a hierarchical tree structure comprising nodes, wherein each of the nodes comprises a respective set of local pointers, and wherein the logical volumes are represented by respective nodes such that the local pointers in the nodes located along a path via the tree structure that connects a given node to a root node of the tree structure point to the physical partitions in which the data used by the logical volume represented by the given node is stored.

21. The apparatus according to claim 20, wherein the local pointers in each node point to the private physical partitions of that node, and wherein the processor is coupled to identify the nodes having non-empty sets of the local pointers as representing the logical volumes having the private partitions.

22. The apparatus according to claim 20, wherein the processor is coupled to permanently delete the logical volumes in the subset by deleting the nodes representing the logical volumes in the subset from the tree structure.

23. The apparatus according to claim 22, wherein the tree structure comprises a binary tree in which the logical volumes are represented by leaf nodes and in which nodes that connect the leaf nodes to the root node comprise artificial nodes, and wherein the processor is coupled to delete a first leaf node, which represents a first logical volume and is located below an artificial node, by:

deleting from the tree structure a second leaf node that represents a second logical volume and is located below the artificial node;

converting the artificial node into a merged node representing the second logical volume; and

combining the local pointers of the second leaf node with the local pointers of the artificial node to produce the local pointers of the merged node.

24. A system for data storage, comprising:

a storage device comprising physical partitions; and

a storage controller, which is coupled to communicate with at least one host computer so as to receive data for storage that is addressed to logical volumes assigned on the storage device, to represent the logical volumes by respective sets of pointers to the physical partitions in which data used by the logical volumes is stored, to define one or more of the logical volumes as provisionally deleted, to select a subset of the provisionally-deleted logical volumes such that each logical volume in the subset has one or more private physical partitions whose data is used exclusively by that logical volume, and to release one or more of the private physical partitions of the logical volumes in the subset for reallocation to another logical volume.

25. A computer software product for data storage, the product comprising a computer-readable medium, in which program instructions are stored, which instructions, when read by the computer, cause the computer to communicate with at least one host computer so as to receive data for storage that is addressed to logical volumes assigned on a storage device having physical partitions, to represent the logical volumes by respective sets of pointers to the physical partitions in which data used by the logical volumes is stored, to define one or more of the logical volumes as provisionally deleted, to select a subset of the provisionally-deleted logical volumes such that each logical volume in the subset has one or more private physical partitions whose data is used exclusively by that logical volume, and to release one or more of the private physical partitions of the logical volumes in the subset for reallocation to another logical volume.