Load Sharing Cluster File Systems

• US 20090210431A1
• Filed: 11/11/2008
• Published: 08/20/2009
• Est. Priority Date: 11/12/2007
• Status: Active Grant

• Current Assignee: RPX Corporation
• Original Assignee: Attune Systems, Inc. (F5 Incorporated)
• Inventors: Marinov, Borislav, Suresh, Suma, Coimbatore, Saravanan, Makkar, Chitra, Marinkovic, Vladan Z., Wong, Thomas K., Vogel, Ron S.
• Granted Patent: US 8,180,747 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/1827 Management specifically adapted to NAS management of storage area networks [SAN] G06F3/067

Abstract

Load sharing clusters in which each node is responsible for one or more non-overlapping subset(s) of the cluster namespace and will process only those requests that access file or directory objects in the partitioned namespace that the node controls while redirecting requests designated for other nodes. A non-overlapping subset may be migrated from a source node to a destination node, for example, for load sharing or hotspot mitigation. Migration typically includes maintaining a file virtualization link from the destination node to the source node to permit forwarding of requests by the destination node to the source node during migration of metadata and then migration of data from the source node. After migration is complete, the file virtualization link is broken and the destination node services requests for the non-overlapping subset from the migrated metadata and data.

Claims

1. In an aggregated filesystem having a cluster of file storage nodes and a distributed filesystem server (DFS) node, the file storage nodes collectively maintaining a shared storage including a plurality of non-overlapping portions, each file storage node owning at least one of the non-overlapping portions and including for each non-overlapping portion not owned by the file storage node a file virtualization link identifying another file storage node for the non-overlapping portion, the DFS node mapping each non-overlapping portion to a file storage node, a method for load sharing by the file storage nodes, the method comprising:

generating client requests by a number of client nodes, each client request identifying a non-overlapping portion and directed to a specific file storage node based on an access to the DFS server or information in a client cache; and

for each client request received by a file storage node, servicing the client request by the receiving file storage node if the receiving file storage node owns the identified non-overlapping portion and otherwise forwarding the client request by the receiving file storage node to another file storage node identified using the file virtualization links.

2. A method according to claim 1, further comprising:

migrating a specified non-overlapping portion from a source file storage node to a destination file server node.

3. A method according to claim 2, wherein the specified non-overlapping portion is migrated due to reconfiguration of the cluster.

4. A method according to claim 2, wherein the specified non-overlapping portion is migrated based on loading of the source file storage node.

5. A method according to claim 2, wherein migrating a specified non-overlapping portion from a source file storage node to a destination file server node comprises:

establishing a file virtualization link on the destination file server node, the file virtualization link identifying the file storage node that owns the non-overlapping portion;

updating the cluster resource to map the non-overlapping portion to the destination file storage node;

building metadata for the non-overlapping portion on the destination file storage node using sparse files such that all file and directory attributes of the non-overlapping portion are replicated on the destination file storage node without any data, and during such building, forwarding client requests received for the non-overlapping portion by the destination file storage node to the file storage node that owns the non-overlapping portion based on the file virtualization link;

after building the metadata for the non-overlapping portion on the destination file storage, copying data for the non-overlapping portion from the source file storage node to the destination file storage node, and during such copying, servicing metadata requests received for the non-overlapping portion by the destination file storage node using the metadata and forwarding data requests received for the non-overlapping portion by the destination file storage node to the file storage node that owns the non-overlapping portion based on the file virtualization link; and

after completion of the copying, designating the destination file storage node as the owner of the non-overlapping portion and thereafter servicing client requests received for the non-overlapping portion by the destination file storage node.

6. A method according to claim 5, wherein the destination file storage node is an existing file storage node in the cluster.

7. A method according to claim 5, wherein the destination file storage node is a new file storage node added to the cluster.

8. In an aggregated filesystem having a plurality of file storage nodes and a distributed filesystem server (DFS) node, the file storage nodes collectively maintaining a shared storage including a plurality of non-overlapping portions, each file storage node owning at least one of the non-overlapping portions and including for each non-overlapping portion not owned by the file storage node a file virtualization link identifying another file storage node for the non-overlapping portion, the DFS node mapping each non-overlapping portion to a file storage node, a method for load sharing by a file storage node, the method comprising:

receiving, by the file storage node, a client request identifying a non-overlapping portion;

when the file storage node owns the identified non-overlapping portion, servicing the client request by the file storage node; and

when the file storage node does not own the identified non-overlapping portion, forwarding the client request by the file storage node to another file storage node identified using the file virtualization links.

9. A method according to claim 8, further comprising:

migrating a specified non-overlapping portion from another file storage node.

10. A method according to claim 9, wherein migrating a specified non-overlapping portion from another file storage node comprises:

maintaining a file virtualization link to the specified non-overlapping portion on the other file storage node;

migrating metadata for the specified non-overlapping portion from the other file storage node;

after migrating the metadata, migrating data for the specified non-overlapping portion from the other file storage node; and

after migrating the data, breaking the file virtualization link.

11. A method according to claim 10, further comprising:

while migrating the metadata, redirecting requests for the specified non-overlapping portion to the other file storage node.

12. A method according to claim 10, further comprising:

while migrating the data, servicing metadata requests for the specified non-overlapping portion from the migrated metadata and forwarding data request for the specified non-overlapping portion to the other file storage node.

13. A method according to claim 10, further comprising:

after breaking the file virtualization link, servicing requests for the specified non-overlapping portion from the migrated metadata and data.

14. A method according to claim 9, wherein migrating the specified non-overlapping portion from the other file storage node is done for at least one of load sharing and hotspot mitigation.

15. A file storage node for use in an aggregated filesystem having a plurality of file storage nodes and a distributed filesystem (DFS) node, the file storage nodes collectively maintaining a shared storage including a plurality of non-overlapping portions, each file storage node owning at least one of the non-overlapping portions and including for each non-overlapping portion not owned by the file storage node a file virtualization link identifying another file storage node for the non-overlapping portion, the DFS node mapping each non-overlapping portion to a file storage node, the file storage node comprising:

a network interface for receiving a client request identifying a non-overlapping portion; and

a processor configured to service the client request if the file storage node owns the identified non-overlapping portion and to forward the client request to another file storage node identified using the file virtualization links if the file storage node does not own the identified non-overlapping portion.

16. A file storage node according to claim 15, wherein the processor is further configured to migrate a specified non-overlapping portion from another file storage node.

17. A file storage node according to claim 16, wherein the processor is configured to migrate a specified non-overlapping portion from another file storage node by maintaining a file virtualization link to the specified non-overlapping portion on the other file storage node;

migrating metadata for the specified non-overlapping portion from the other file storage node;

after migrating the metadata, migrating data for the specified non-overlapping portion from the other file storage node; and

after migrating the data, breaking the file virtualization link.

18. A file storage node according to claim 17, wherein the processor is configured to redirect requests for the specified non-overlapping portion to the other file storage node while migrating the metadata.

19. A file storage node according to claim 17, wherein the processor is configured to service metadata requests for the specified non-overlapping portion from the migrated metadata and forward data request for the specified non-overlapping portion to the other file storage node while migrating the data.

20. A file storage node according to claim 17, where in the processor is configured to service requests for the specified non-overlapping portion from the migrated metadata and data after breaking the file virtualization link.