Shared file system having a token-ring style protocol for managing meta-data

• US 6,665,675 B1
• Filed: 09/07/2000
• Issued: 12/16/2003
• Est. Priority Date: 09/07/2000
• Status: Expired due to Term

• Current Assignee: Harmonic Incorporated
• Original Assignee: Omneon Video Networks
• Inventors: Mitaru, Alexandru
• Primary Examiner(s): Mizrahi, Diane D.
• Application Number:
  US09/657,079
• Time in Patent Office: 1,195 Days
• Field of Search: 707/10, 707/103.R, 709/203, 709/225, 709/226, 709/231, 709/218, 717/108, 714/35, 714/39, 714/48, 714/49, 370/403
• US Class Current: 1/1
• CPC Class Codes: H04L 67/1095 Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A system is disclosed having shared storage nodes and a number of processing nodes coupled to the shared storage nodes. The storage nodes are to store user data and file system meta-data (FSMD) and can be accessed by the processing nodes. Each respective processing node stores a copy of the FSMD, and can update its copy of the FSMD based upon content of a token received from one of the processing nodes. The processing node adds information to the token that describes a change that node makes to the copy of the FSMD, and then sends the token to another one of the processing nodes. Such a scheme may prove to be a more scalable solution for a shared file system as the number of processing nodes are increased, because the overhead associated with managing the meta-data does not significantly diminish the performance of the storage system as a whole.

Claims

1. A system comprising:

one or more shared storage nodes to store user data and file system meta-data (FSMD); and

a plurality of processing nodes coupled to the shared storage nodes, each respective processing node having a processor and a memory, the memory containing a plurality of instructions which, when executed by the processor, cause the respective processing node to (1) disallow changes to a stored copy of the FSMD unless a token is present, (2) update the copy of the FSMD based upon content of the token received from one of the plurality of processing nodes, (3) add information to the token that describes a change that node makes to the copy of the FSMD, and then (4) send the token to another one of the processing nodes.

2. The system of claim 1 wherein in each respective processing node, the memory includes further instructions which, when executed by the processor, cause that node to be part of a virtual ring made of the plurality of processing nodes, the token to be passed around the ring to give each of the plurality of processing nodes a fair chance to change a copy of the FSMD.

3. The system of claim 2 wherein in each respective processing node, the memory includes further instructions which, when executed by the processor, delete information in the token that describes a change that node made to the copy of the FSMD a previous time that node had the token.

4. The system of claim 1 wherein each respective processing node further comprises non-volatile memory to store a journal that describes changes made to the FSMD.

5. The system of claim 4 wherein in each respective processing node, the memory includes further instructions which, when executed by the processor, cause that node to write the journal to the shared storage nodes when the non-volatile memory is close to being full.

6. An article of manufacture suitable for use as part of a shared storage system having (1) one or more shared storage nodes to store user data and file system meta-data (FSMD) and (2) a plurality of processing nodes coupled to the shared storage node, each respective processing node having a processor, the article of manufacture comprising:

a machine-readable medium containing a plurality of instructions which, when executed by the processor, cause the respective processing node to (1) disallow changes to a stored copy of the FSMD unless a token is present, (2) update the copy of the FSMD based upon content of the token received from one of the plurality of processing nodes, (3) add information to the token that describes a change that node makes to the copy of the FSMD, and then (4) send the token to another one of the processing nodes.

7. The article of manufacture of claim 6 wherein the machine-readable medium includes further instructions which, when executed by the processor, cause that node to be part of a virtual ring made of the plurality of processing nodes, the token to be passed around the ring to give each of the plurality of processing nodes a fair chance to change a copy of the FSMD.

8. The article of manufacture of claim 7 wherein the machine-readable medium includes further instructions which, when executed by the processor, delete information in the token that describes a change that node made to the copy of the FSMD a previous time that node had the token.

9. The article of manufacture of claim 6 wherein the machine-readable medium includes a non-volatile portion to store a journal that describes changes made to the copy of the FSMD.

10. The article of manufacture of claim 9 wherein the machine readable medium includes further instructions which, when executed by the processor, cause that node to write the journal to the shared storage nodes when the non-volatile memory is close to being full.

11. In a processing node, a method for managing file system meta-data (FSMD), comprising:

disallowing changes to the FSMD unless a token is present;

updating a stored copy of the FSMD based upon content of the token received from one of a plurality of processing nodes;

adding information to the token that describes a change the processing node makes to the copy of the FSMD; and

then

sending the token to another one of the processing nodes.

12. The method of claim 11 further comprising:

forming a virtual ring made of the plurality of processing nodes, the token to be passed around the ring to give each of the plurality of processing nodes a fair chance to change the FSMD.

13. The method of claim 12 further comprising:

deleting information in the token that describes a change the processing node made to the copy of the FSMD a previous time that node had the token.

14. The method of claim 11 further comprising storing a journal that describes changes made to the FSMD in non-volatile memory.

15. The method of claim 14 further comprising:

writing the journal to the storage nodes when the non-volatile memory is close to being full.