FILE SYSTEM INDEPENDENT CONTENT AWARE CACHE

• US 20130167155A1
• Filed: 11/13/2012
• Published: 06/27/2013
• Est. Priority Date: 04/26/2010
• Status: Active Grant

• Current Assignee: Vmware LLC (Broadcom, Inc.)
• Original Assignee: VMware, Inc. (Broadcom, Inc.)
• Inventors: DAVIS, Scott Howard
• Granted Patent: US 8,776,089 B2
• Time in Patent Office: Days
• US Class Current: 719/312
• CPC Class Codes: G06F 12/084 with a shared cache
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 2212/222 Non-volatile memory
• CPC Class Codes: G06F 2212/465 Structured object, e.g. database record

Abstract

A server supporting the implementation of virtual machines includes a local memory used for caching, such as a solid state device drive. During I/O intensive processes, such as a boot storm, a “content aware” cache filter component of the server first accesses a cache structure in a content cache device to determine whether data blocks have been stored in the cache structure prior to requesting the data blocks from a networked disk array via a standard I/O stack of the hypervisor.

Claims

1. A method for obtaining data for a virtual machine in a server supporting a hypervisor for running virtual machines, the method comprising:

receiving a read request from the virtual machine intended for transmission to a virtual drive that is accessed through a root virtual machine running in the server;

confirming that the read request corresponds to a specific content type in the virtual drive;

identifying an entry in a cache index, wherein the entry includes (i) information that matches (a) an address offset in the read request and (b) an identity associated with the virtual machine, and (ii) a reference to data stored in a cache maintained in a local memory in the server;

circumventing a standard I/O stack of the root virtual machine used to access the virtual drive by requesting the data directly from the local memory by providing address information corresponding to the reference to a driver for the local memory;

receiving the data from the driver for the local memory; and

transmitting the data to the virtual machine in response to the read request.

2. The method of claim 1, wherein the specific content type relates to data in a boot image in the virtual drive.

3. The method of claim 2, wherein the server is networked to a disk array that stores an actual boot image comprising data blocks of the boot image in the virtual drive.

4. The method of claim 1, wherein the local memory is a solid state drive in the server.

5. The method of claim 1, wherein the reference is a hash value corresponding to an entry in a hash table including the address information, which is used to access the data stored in the cache.

6. The method of claim 5, wherein the reference is included in at least one other entry in the cache index that includes an identity associated with another virtual machine.

7. The method of claim 1, wherein the steps are performed by a cache filter component running in the root virtual machine.

8. A computer-readable storage medium including instructions that, when executed by a computer processor of a server supporting a hypervisor for running virtual machines, causes the computer processor obtain data for a virtual machine by performing the steps of:

receiving a read request from the virtual machine intended for transmission to a virtual drive that is accessed through a root virtual machine running in the server;

confirming that the read request corresponds to a specific content type in the virtual drive;

identifying an entry in a cache index, wherein the entry includes (i) information that matches (a) an address offset in the read request and (b) an identity associated with the virtual machine, and (ii) a reference to data stored in a cache maintained in a local memory in the server;

circumventing a standard I/O stack of the root virtual machine used to access the virtual drive by requesting the data directly from the local memory by providing address information corresponding to the reference to a driver for the local memory;

receiving the data from the driver for the local memory; and

transmitting the data to the virtual machine in response to the read request.

9. The computer-readable storage medium of claim 8, wherein the specific content type relates to data in a boot image in the virtual drive.

10. The computer-readable storage medium of claim 9, wherein the server is networked to a disk array that stores an actual boot image comprising data blocks of the boot image in the virtual drive.

11. The computer-readable storage medium of claim 8, wherein the local memory is a solid state drive in the server.

12. The computer-readable storage medium of claim 8, wherein the reference is a hash value corresponding to an entry in a hash table including the address information, which is used to access the data stored in the cache.

13. The computer-readable storage medium of claim 12, wherein the reference is included in at least one other entry in the cache index that includes an identity associated with another virtual machine.

14. The computer-readable storage medium of claim 8, wherein the steps are performed by a cache filter component running in the root virtual machine.

15. A server supporting a hypervisor for running virtual machines and configured to obtain data for a virtual machine running in the server, the server comprising a processor configured to perform the steps of:

receiving a read request from the virtual machine intended for transmission to a virtual drive that is accessed through a root virtual machine running in the server;

confirming that the read request corresponds to a specific content type in the virtual drive;

identifying an entry in a cache index, wherein the entry includes (i) information that matches (a) an address offset in the read request and (b) an identity associated with the virtual machine, and (ii) a reference to data stored in a cache maintained in a local memory in the server;

circumventing a standard I/O stack of the root virtual machine used to access the virtual drive by requesting the data directly from the local memory by providing address information corresponding to the reference to a driver for the local memory;

receiving the data from the driver for the local memory; and

transmitting the data to the virtual machine in response to the read request.

16. The server of claim 15, wherein the specific content type relates to data in a boot image in the virtual drive.

17. The server of claim 16, wherein the server is networked to a disk array that stores an actual boot image comprising data blocks of the boot image in the virtual drive.

18. The server of claim 15, wherein the local memory is a solid state drive in the server.

19. The server of claim 15, wherein the reference is a hash value corresponding to an entry in a hash table including the address information, which is used to access the data stored in the cache.

20. The server of claim 15, wherein the reference is included in at least one other entry in the cache index that includes an identity associated with another virtual machine.