Disk volume virtualization block-level caching

• US 6,957,294 B1
• Filed: 11/15/2002
• Issued: 10/18/2005
• Est. Priority Date: 11/15/2002
• Status: Expired due to Fees

• Current Assignee: Unisys Corporation
• Original Assignee: Unisys Corporation
• Inventors: Hunter, James R., Grzegorek, Richard, Yip, Vincent S., Neill, Joseph P., Saunders, Michael J.
• Primary Examiner(s): Sparks, Donald
• Assistant Examiner(s): FARROKH, HASHEM
• Application Number:
  US10/295,161
• Time in Patent Office: 1,068 Days
• Field of Search: 711111-115, 711/119, 711/136, 711141-143, 711/153, 711/173, 711 4- 6, 711100-105, 711161-162, 709214-215, 709217-219, 709/223, 709/226, 709/321, 709220-221, 709/229
• US Class Current: 711/4
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 2003/0697 device management, e.g. handlers, drivers, I/O schedulers
• CPC Class Codes: G06F 2212/311 In host system
• CPC Class Codes: G06F 3/0601 Interfaces specially adapted for storage systems

Abstract

The present invention provides systems and methods for allocating a pool of global memory among a set of client/servers so that storage volumes associated with a plurality of client/servers are each allocated a portion of the pool of global memory for caching of data from that volume. The amount of memory to be used for caching the volume'"'"'s input/output operations (I/Os), the page size, the cache type, the cache replacement policy and the maximum cache read can be specified by volume. The amount of memory to be used for caching the volume'"'"'s input/output operations, the cache type, the cache replacement policy and the maximum cache read I/O size can be changed dynamically by the changing volume-based attributes.

Claims

1. A system for accessing data on a computer storage medium, comprising:

at least one storage unit coupled to a resource manager, the at least one storage unit partitioned into at least one of a plurality of volumes;

the resource manager managing a pool of available memory, wherein the pool is allocated among the plurality of volumes according to a set of attributes associated with each volume, wherein the set of attributes comprises a size of caching space that can be changed dynamically, and wherein the pool of available memory may be dynamically reallocated among the plurality of volumes.

2. The system of claim 1 wherein the set of attributes associated with each volume further comprises at least one of:

a caching page size, a cache type, a cache replacement policy and a maximum cache read size.

3. The system of claim 2 wherein the maximum cache read size specified by volume can be changed dynamically.

4. The system of claim 1 further comprising at least one of a plurality of clients coupled to the resource manager, wherein the at least one client is associated with the at least one volume.

5. The system of claim 1 wherein the resource manager comprises a volume disk cache driver.

6. The system of claim 5 wherein the volume disk cache driver receives an input/output request from a requestor, the input/output request requesting data from a first volume, the first volume associated with a first volume disk cache space.

7. The system of claim 6 wherein the volume disk cache driver returns the requested data to the requestor from the first volume disk cache space.

8. The system of claim 1 wherein the resource manager further comprises an interface for changing the set of attributes associated with at least one volume of the plurality of volumes.

9. The system of claim 1 wherein the volume disk cache driver is implemented as a upper level filter to a logical disk manager.

10. A method of volume disk caching comprising:

reserving a pool of memory for caching at least one of a plurality of logical disk volumes;

receiving an attribute value associated with a size of the pool of memory to be reserved;

allocating the pool of memory among the at least one of a plurality of logical disk volumes in accordance with a set of attributes associated with the at least one logical disk volume, wherein the set of attributes comprises a size of caching space that can be changed dynamically.

11. The method of claim 10 further comprising reserving the pool of memory from system memory.

12. The method of claim 10 further comprising dynamically reallocating the pool of memory in response to receiving an updated set of attributes associated with at least one of the volumes.

13. The method of claim 10 wherein the set of attributes includes an attribute for setting the amount of memory to be used for caching the at least one logical disk volume.

14. The method of claim 13, wherein the attribute can be changed without interrupting caching.

15. The method of claim 10 wherein the set of attributes includes an attribute for setting the size of each cache page for the at least one logical disk volume.

16. The method of claim 10 wherein the attributes includes an attribute for setting the type of caching to be used to write through caching.

17. The method of claim 10 wherein the set of attributes includes an attribute for setting the type of caching to be used to write back caching.

18. The method of claim 10 wherein the set of attributes includes an attribute for specifying a cache replacement policy.

19. The method of claim 18 wherein the attribute can be changed without stopping caching.

20. The method of claim 10 wherein the set of attributes includes an attribute for setting the size of the largest cache read operation.

21. The method of claim 20 wherein the attribute can be changed without stopping caching.

22. A computer-readable medium having stored thereon program code for performing volume-based caching, the program code when executed by a computer causing the computer to:

reserve a pool of memory for caching at least one of a plurality of logical disk volumes;

receive an attribute value associated with a size of the pool of memory to be reserved; and

allocate the pool of memory among the at least one of a plurality of logical disk volumes in accordance with a set of attributes associated with the at least one logical disk volume, wherein the set of attributes comprises a size of caching space that can be changed dynamically.