System and method for caching network file systems

• US 20070250552A1
• Filed: 04/24/2006
• Published: 10/25/2007
• Est. Priority Date: 04/25/2005
• Status: Active Grant

• Current Assignee: NetApp, Inc.
• Original Assignee: NetApp, Inc.
• Inventors: Lango, Jason, Zheng, Qinghua, Grunwald, David, Ayyar, Kartik, Prakash, Ashish, Ackaouy, Emmanuel, Griess, Peter, Eastham, Paul, Quirion, Brian, Wagner, J., Amdur, Matthew, English, Robert, Tsai, Robert
• Granted Patent: US 8,055,702 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 15/167 using a common memory, e.g. mailbox
• CPC Class Codes: G06F 2003/0697 device management, e.g. handlers, drivers, I/O schedulers
• CPC Class Codes: G06F 3/0601 Interfaces specially adapted for storage systems
• CPC Class Codes: G06F 3/0617 in relation to availability
• CPC Class Codes: G06F 3/0643 Management of files
• 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]
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD
• CPC Class Codes: H04L 67/565 Conversion or adaptation of application format or content adding application control or application functional data H04L67/561
• CPC Class Codes: H04L 67/568 Storing data temporarily at an intermediate stage, e.g. caching
• CPC Class Codes: H04L 67/59 Providing operational support to end devices by off-loading in the network or by emulation, e.g. when they are unavailable

Abstract

A network caching system has a multi-protocol caching filer coupled to an origin server to provide storage virtualization of data served by the filer in response to data access requests issued by multi-protocol clients over a computer network. The multi-protocol caching filer includes a file system configured to manage a sparse volume that “virtualizes” a storage space of the data to thereby provide a cache function that enables access to data by the multi-protocol clients. To that end, the caching filer further includes a multi-protocol engine configured to translate the multi-protocol client data access requests into generic file system primitive operations executable by both the caching filer and the origin server.

Claims

1. A network caching system comprising:

an origin server; and

a caching filer coupled to the origin server, the caching filer having a file system configured to manage a sparse volume that virtualizes a storage space of data to thereby provide storage virtualization of data served by the filer in response to data access requests issued by multi-protocol clients.

2. The network caching system of claim 1 further comprising a multi-protocol engine of the caching filer, the multi-protocol engine configured to translate the multi-protocol data access requests issued by the multi-protocol clients into file system operations executable by both the caching filer and the origin server.

3. The network caching system of claim 2 further comprising a local cache of the caching filer, the local cache including the sparse volume adapted to serve data requested by one or more clients from one or more storage objects having at least one absent block representing data that is missing from the sparse volume, wherein the missing data of the absent block is stored on the origin server and retrieved using a remote fetch operation in a manner that is transparent to the client.

4. The network caching system of claim 3 wherein the storage object is one of a file and logical unit number.

5. The network caching system of claim 3 wherein the sparse volume is a cache volume comprising one or more disks coupled to the caching filer.

6. The network caching system of claim 5 further comprising a remote update engine (RUE) of the caching filer, the RUE configured to forward any file system operations that modify the cache volume to the origin server.

7. The network caching system of claim 6 further comprising a truncator of the caching filer, the truncator configured to implement a cache ejection policy to reclaim storage space as the cache volume becomes full.

8. A method for operating a network caching system comprising:

receiving a data access request directed to a storage object at a caching filer of the system;

determining whether the data access request modifies data stored on a cache volume of the caching filer;

if so, conveying the data access request from the caching filer to an origin server of the system; and

processing the data access request at the origin server.

9. The method of claim 8 further comprising:

if the data access request does not modify data stored on the cache volume, passing the request into a file system of the caching filer;

determining whether data requested by the request is resident on a local cache of the caching filer;

if not, generating one or more fetch operations at the caching filer to retrieve the requested data from the origin server; and

upon receiving a response from the origin server, storing the retrieved data in the local cache of the caching filer.

10. The method of claim 9 further comprising:

if the requested data is resident on the local cache of the caching filer, servicing the request at the caching filer.

11. A method for operating a network caching system comprising:

receiving a data access request directed to a storage object at a caching filer of the system;

sending a fetch on demand (FOD) request from the caching filer to an origin server of the system, the FOD request requesting a latest copy of attributes of the storage object;

determining whether a change occurred in any of the attributes since the storage object was cached at the caching filer; and

if so, triggering an ejection of the storage object stored on a local cache of the caching filer.

12. The method of claim 11 wherein the storage object is one of a file and logical unit number.

13. The method of claim 11 wherein the attributes include a modification time of the storage object and a creation time of the storage object.

14. The method of claim 13 wherein a change occurring in any of the attributes indicates that the storage object had been modified since cached at the caching filer.

15. The method of claim 11 further comprising:

generating one or more fetch operations at the caching filer to retrieve the requested data from the origin server.

16. The method of claim 15 wherein each fetch operation is embodied as a NRV read message.

17. Apparatus for operating a network caching system comprising:

means for receiving a data access request directed to a storage object at a caching filer of the system;

means for determining whether the data access request modifies data stored on a cache volume of the caching filer;

if so, means for conveying the data access request from the caching filer to an origin server of the system; and

means for processing the data access request at the origin server.

18. The apparatus of claim 17 further comprising:

if the data access request does not modify data stored on the cache volume, means for passing the request into a file system of the caching filer;

means for determining whether data requested by the request is resident on a local cache of the caching filer;

if not, means for generating one or more fetch operations at the caching filer to retrieve the requested data from the origin server; and

upon receiving a response from the origin server, means for storing the retrieved data in the local cache of the caching filer.

19. A computer readable medium containing executable program instructions for operating a network caching system, the executable instructions comprising one or more program instructions for:

receiving a data access request directed to a storage object at a caching filer of the system;

determining whether the data access request modifies data stored on a cache volume of the caching filer;

if so, conveying the data access request from the caching filer to an origin server of the system; and

processing the data access request at the origin server.

20. The computer readable medium of claim 19 further comprising one or more program instructions for:

if the data access request does not modify data stored on the cache volume, passing the request into a file system of the caching filer;

determining whether data requested by the request is resident on a local cache of the caching filer;

if not, generating one or more fetch operations at the caching filer to retrieve the requested data from the origin server; and

upon receiving a response from the origin server, storing the retrieved data in the local cache of the caching filer.