SYSTEM SOFTWARE INTERFACES FOR SPACE-OPTIMIZED BLOCK DEVICES

• US 20120054410A1
• Filed: 07/12/2011
• Published: 03/01/2012
• Est. Priority Date: 08/30/2010
• Status: Active Grant

• Current Assignee: Vmware LLC (Broadcom, Inc.)
• Original Assignee: VMware, Inc. (Broadcom, Inc.)
• Inventors: VAGHANI, Satyam B., ASWATHANARAYANA, Tejasvi
• Granted Patent: US 9,052,825 B2
• Time in Patent Office: Days
• US Class Current: 711/6
• CPC Class Codes: G06F 11/1484 involving virtual machines
• CPC Class Codes: G06F 12/06 Addressing a physical block of locations, e.g. base addressing, module addressing, memory dedication G06F12/08 takes precedence
• CPC Class Codes: G06F 12/08 in hierarchically structured memory systems, e.g. virtual memory systems
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/0629 Configuration or reconfiguration of storage systems
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0644 Management of space entities, e.g. partitions, extents, pools
• CPC Class Codes: G06F 3/0664 at device level, e.g. emulation of a storage device or system
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]

Abstract

Interfaces to storage devices that employ storage space optimization technologies, such as thin provisioning, are configured to enable the benefits gained from such technologies to be sustained. Such an interface may be provided in a hypervisor of a virtualized computer system to enable the hypervisor to discover features of a logical unit number (LUN), such as whether or not the LUN is thinly provisioned, and also in a virtual machine (VM) of the virtualized computer system to enable the VM to discover features of a virtual disk, such as whether or not the virtual disk is thinly provisioned. The discovery of these features enables the hypervisor or the VM to instruct the underlying storage device to carry out certain operations such as an operation to deallocate blocks previously allocated to a logical block device, so that the storage device can continue to benefit from storage space optimization technologies implemented therein.

Claims

1. A method of determining features of a logical block device for a computer system, comprising:

querying the logical block device with a first query and receiving a response thereto from the logical block device that indicates whether or not the logical block device is thinly provisioned; and

querying the logical block device with a second query and receiving a response thereto from the logical block device that indicates whether or not the logical block device supports an unmap command, wherein the unmap command is a command to deallocate blocks previously allocated to the logical block device.

2. The method of claim 1, wherein the response to the second query further includes an alignment value and a granularity value, the alignment value specifying an offset at which the logical block device performs space reclamation operations, and the granularity value specifying a unit size at which the logical block device performs space reclamation operations.

3. The method of claim 2, wherein the response to the second query further includes an integer value that represents the maximum number of arguments that can be included in a single unmap command.

4. The method of claim 2, wherein the logical block device is a logical unit number (LUN) and the computer system includes a file system that is interfaced with the logical block device.

5. The method of claim 4, wherein the computer system has a virtual machine executing therein and the file system is a component of a virtualization software that supports execution of the virtual machine.

6. The method of claim 5, wherein the virtualization software layer emulates physical hardware for the virtual machine including a virtual disk that is managed as a file stored in the logical block device.

7. The method of claim 6, further comprising:

querying, from within the virtual machine, the virtual disk with a third query and receiving a response thereto from the virtual disk that indicates whether or not the virtual disk is thinly provisioned; and

querying, from within the virtual machine, the virtual disk with a fourth query and receiving a response thereto from the virtual disk that indicates whether or not the virtual disk supports an unmap command, wherein the unmap command is a command to deallocate blocks previously allocated to the virtual disk.

8. The method of claim 7, wherein the response to the fourth query further includes an alignment value and a granularity value, the alignment value specifying an offset at which the logical block device performs space reclamation operations, and the granularity value specifying a unit size at which the logical block device performs space reclamation operations.

9. The method of claim 8, wherein the response to the fourth query further includes an integer value that represents the maximum number of arguments that can be included in a single unmap command issued to the virtual disk.

10. The method of claim 1, wherein the computer system is a virtual machine executing in a host and the logical block device is a virtual disk for the virtual machine, and the virtual machine includes a file system that is interfaced with the virtual disk.

11. The method of claim 10, wherein the host includes a virtualization software that supports execution of the virtual machine and emulates physical hardware for the virtual machine including the virtual disk.

12. The method of claim 11, wherein the response to the second query further includes an alignment value and a granularity value, the alignment value specifying an offset at which the logical block device performs space reclamation operations, and the granularity value specifying a unit size at which the logical block device performs space reclamation operations.

13. The method of claim 12, wherein the response to the second query further includes an integer value that represents the maximum number of arguments that can be included in a single unmap command.

14. A non-transitory computer readable storage medium comprising instructions executable by a computer system to carry out a method of determining features of a logical block device for the computer system, said method comprising:

querying the logical block device with a first query and receiving a response thereto from the logical block device that indicates whether or not the logical block device is thinly provisioned; and

querying the logical block device with a second query and receiving a response thereto from the logical block device that indicates whether or not the logical block device supports an unmap command, wherein the unmap command is a command to deallocate blocks previously allocated to the logical block device.

15. The non-transitory computer readable storage medium of claim 14, wherein the response to the second query further includes an alignment value and a granularity value, the alignment value specifying an offset at which the logical block device performs space reclamation operations, and the granularity value specifying a unit size at which the logical block device performs space reclamation operations.

16. The non-transitory computer readable storage medium of claim 15, wherein the response to the second query further includes an integer value that represents the maximum number of arguments that can be included in a single unmap command.

17. The non-transitory computer readable storage medium of claim 15, wherein the logical block device is a logical unit number (LUN) and the computer system has a file system that is interfaced with the logical block device.

18. The non-transitory computer readable storage medium of claim 15, wherein the computer system is a virtual machine to be executed in a host and the logical block device is a virtual disk for the virtual machine.

19. A computer system interfaced with a logical block device, comprising:

an interface component that interfaces the computer system to the logical block device; and

a processor and memory,

wherein the processor is programmed to query the logical block device with a first query and receive a response thereto from the logical block device that indicates whether or not the logical block device is thinly provisioned, and query the logical block device with a second query and receive a response thereto from the logical block device that indicates whether or not the logical block device supports an unmap command, wherein the unmap command is a command to deallocate blocks previously allocated to the logical block device.

20. The computer system of claim 19, wherein the response to the second query further includes an alignment value and a granularity value, the alignment value specifying an offset at which the logical block device performs space reclamation operations, and the granularity value specifying a unit size at which the logical block device performs space reclamation operations.

21. The computer system of claim 20, wherein the response to the second query further includes an integer value that represents the maximum number of arguments that can be included in a single unmap command.

22. The computer system of claim 20, wherein the processor is programmed to execute a virtual machine and a virtual disk for the virtual machine, and wherein the virtual machine queries the virtual machine with a third query and receives a response thereto from the virtual disk that indicates whether or not the virtual disk is thinly provisioned, and queries the virtual disk with a fourth query and receive a response thereto from the virtual disk that indicates whether or not the virtual disk supports an unmap command, wherein the unmap command is a command to deallocate blocks previously allocated to the virtual disk.

23. The computer system of claim 20, wherein the response to the fourth query further includes an alignment value and a granularity value, the alignment value specifying an offset at which the logical block device performs space reclamation operations, and the granularity value specifying a unit size at which the logical block device performs space reclamation operations.

24. The computer system of claim 23, wherein the response to the fourth query further includes an integer value that represents the maximum number of arguments that can be included in a single unmap command issued to the virtual disk.

25. A computer system comprising:

a plurality of hosts, each having virtualization software to support execution of one or more virtual machines, the hosts including first and second hosts each having virtualization software of a first type that supports thinly provisioned virtual disks and an unmap command, wherein the unmap command is a command for deallocating blocks previously allocated to a thinly provisioned virtual disk, and a third host having virtualization software of a second type that does not support thinly provisioned virtual disks or the unmap command; and

a management server for the virtual machines having a resource scheduling software executed therein to recommend live migration of virtual machines between two hosts other than from a host having a virtualization software of the first type to a host having a virtualization software of the second type.

26. The computer system of claim 25, wherein each of the hosts having a virtualization software of the first type includes:

an interface component that interfaces the host to a logical block device; and

a processor and memory,

wherein the processor is programmed to query the logical block device with a first query and receive a response thereto from the logical block device that indicates whether or not the logical block device is thinly provisioned, and query the logical block device with a second query and receive a response thereto from the logical block device that indicates whether or not the logical block device supports an unmap command, wherein the unmap command is a command to deallocate blocks previously allocated to the logical block device.

27. The computer system of claim 26, wherein the response to the second query further includes an alignment value and a granularity value, the alignment value specifying an offset at which the logical block device performs space reclamation operations, and the granularity value specifying a unit size at which the logical block device performs space reclamation operations.

28. The computer system of claim 27, wherein the response to the second query further includes an integer value that represents the maximum number of arguments that can be included in a single unmap command.