Methods and systems for improved data caching in a virtualized environment

1. A machine implemented method, comprising:

mapping a plurality of virtual hard drives to a logical unit number (LUN) of a storage system, each virtual hard drive including a logical block address (LBA) range of the storage system LUN;

storing the mapping in a caching module data structure;

determining that one of the virtual hard drives should be cached; and

updating the caching module data structure to indicate that the LBA range associated with the one of the virtual hard drives should be cached.

2. The machine implemented method of claim 1 further comprising:

receiving an input/output (I/O) command from a virtual machine, the I/O command relating to an I/O LUN for a command data length; and

when the caching data structure indicates that caching is allowed for a LBA range referenced by the I/O LUN and command data length, processing the I/O command for a cache LUN.

3. The machine implemented method of claim 2 further comprising: forwarding the I/O command to the storage system.

4. The machine implemented method of claim 3 , wherein forwarding the I/O command is a lower priority when the I/O command has been processed for the cache LUN than when it has not.

5. The machine implemented method of claim 1 , wherein determining that one of the virtual hard drives should be cached includes receiving input from a system manager.

6. The machine implemented method of claim 1 , wherein determining that one of the virtual hard drives should be cached includes tracking I/O statistics for the virtual hard drives.

7. A machine implemented method comprising:

selecting a virtual machine for which to provide caching;

obtaining parameters of a virtual disk associated with the virtual machine, the parameters including a storage LUN identity and a LBA range;

updating a caching module data structure with the storage LUN identity and the LBA range to allow caching;

receiving an I/O command from a virtual machine, the I/O command for reading from or writing to an I/O LUN at an LBA start location for a data length;

checking the I/O LUN and the data length against the caching module data structure to determine if the I/O command relates to an LBA range that allows caching; and

processing the I/O command for a cache LUN, when the determination is that the LBA range allows caching.

8. The machine implemented method of claim 7 wherein the caching module data structure comprises a plurality of LUN identifiers (IDs) corresponding to LUNs available to the virtual machine, each LUN ID having a plurality of associated LBA ranges, and each associated LBA range having an associated cache approval indicator.

9. The machine implemented method of claim 8 wherein checking the I/O LUN and the data length against the caching module data structure to determine if the I/O command relates to an LBA range that allows caching, comprises:

finding the I/O LUN in the plurality of LUN IDs;

finding a matching LBA range from the plurality of associated LBA ranges that corresponds to the LBA start location and the data length; and

checking the associated cache approval indicator for the matching LBA range.

10. A non-transitory, machine readable storage medium storing executable instructions, which when executed by a machine, causes the machine to perform a method, the method comprising:

mapping a plurality of virtual hard drives to a logical unit number (LUN) of a storage system, each virtual hard drive including a logical block address (LBA) range of the storage system LUN;

storing the mapping in a caching module data structure;

determining that one of the virtual hard drives should be cached; and

updating the caching module data structure to indicate that the LBA range associated with the one of the virtual hard drives should be cached.

11. The storage medium of claim 10 , the method further comprising:

receiving an input/output (I/O) command from a virtual machine, the I/O command relating to an I/O LUN for a command data length; and

when the caching data structure indicates that caching is allowed for a LBA range referenced by the I/O LUN and command data length, processing the I/O command for a cache LUN.

12. The storage medium of claim 11 , the method further comprising: forwarding the I/O command to the storage system.

13. The storage medium of claim 12 , wherein forwarding the I/O command is a lower priority when the I/O command has been processed for the cache LUN than when it has not.

14. The storage medium of claim 10 , wherein determining that one of the virtual hard drives should be cached includes receiving input from a system manager.

15. The storage medium of claim 10 , wherein determining that one of the virtual hard drives should be cached includes tracking I/O statistics for the virtual hard drives.

16. A system comprising:

a processor executing instructions out of a memory for:

mapping a plurality of virtual hard drives to a logical unit number (LUN) of a storage system, each virtual hard drive including a logical block address (LBA) range of the storage system LUN;

storing the mapping in a caching module data structure;

determining that one of the virtual hard drives should be cached; and

updating the caching module data structure to indicate that the LBA range associated with the one of the virtual hard drives should be cached.

17. The system of claim 16 further including instructions for:

receiving an input/output (I/O) command from a virtual machine, the I/O command relating to an I/O LUN for a command data length; and

when the caching data structure indicates that caching is allowed for the LBA range referenced by the I/O LUN and command data length, processing the I/O command for a cache LUN.

18. The system of claim 17 further including instructions for: forwarding the I/O command to the storage system.

19. The system of claim 18 , wherein forwarding the I/O command is a lower priority when the I/O command has been processed for the cache LUN than when it has not.

20. The system of claim 16 , wherein determining that one of the virtual hard drives should be cached includes receiving input from a system manager.

21. The system of claim 16 , wherein determining that one of the virtual hard drives should be cached includes tracking I/O statistics for the virtual hard drives.