Clustered filesystem

• US 20030078946A1
• Filed: 06/05/2002
• Published: 04/24/2003
• Est. Priority Date: 06/05/2001
• Status: Active Grant

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Silicon Graphics Incorporated (Graphics Properties Holdings, Inc.)
• Inventors: Mowat, Eric, Leong, James, Costello, Laurie
• Granted Patent: US 6,950,833 B2
• Time in Patent Office: Days
• US Class Current: 707/201
• CPC Class Codes: G06F 11/2064 while ensuring consistency
• CPC Class Codes: G06F 11/2082 Data synchronisation
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: H04L 67/10 in which an application is distributed across nodes in the network software deployment G06F8/60; multiprogramming arrangements G06F9/46
• CPC Class Codes: H04L 67/564 Enhancement of application control based on intercepted application data
• CPC Class Codes: H04L 67/566 Grouping or aggregating service requests, e.g. for unified processing
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: Y10S 707/99933 Query processing, i.e. searching
• CPC Class Codes: Y10S 707/99938 Concurrency, e.g. lock management in shared database
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

A cluster of computer system nodes share direct read/write access to storage devices via a storage area network using a cluster filesystem. Version information about subsystems is acquired by a leader node when forming a cluster membership and distributed to all nodes in the cluster to enable proper messaging during operation. Access to files on the storage devices is arbitrated by the cluster filesystem using tokens. Upon detection of a change in location of the metadata server, client nodes waiting for a token are interrupted to check on the status of at least one of data and node availability. The cluster operating system maintains consistency of a mirrored data volume by automatically ensuring replication of a mirror leg while continuing to accept access requests to the mirrored data volume.

Claims

1. A cluster of computer systems, comprising:

storage devices storing at least one mirrored data volume with at least two mirror legs;

a storage area network coupled to said storage devices; and

computer system nodes, coupled to said storage area network, sharing direct read/write access to said storage devices and maintaining mirror consistency during normal operation and upon failure of at least one of said storage devices or at least one of said computer system nodes, while continuing to accept access requests to the mirrored data volume.

2. A method of maintaining mirror consistency of data volumes in a cluster of computer system nodes sharing direct read/write access to storage devices via a storage area network, comprising:

automatically ensuring replication of a mirror leg in response to detection that a failed process was writing to a mirrored data volume;

accepting access requests to the mirrored data volume while reading data from an intact mirror leg and writing the data back to the mirrored data volume; and

processing the access requests that do not interfere with the creation of a replacement mirror leg while postponing processing of interfering access requests until there is no interference.

3. A method as recited in claim 2, wherein said ensuring comprises

detecting failure of at least process accessing the mirrored data volume;

detecting and aborting any outstanding input/output operations requested by the at least one process; and

initiating a mirror revive process if a write operation from the at least one process to a mirrored volume is detected.

4. A method as recited in claim 3,

wherein the mirror revive process comprises

holding input/output requests from the computer system nodes made during the mirror revive process in an overlap queue;

reading from a first range of addresses on an intact leg of the mirrored data volume and writing to first range of addresses on all legs of the mirrored data volume after ensuring that all input/output activity to the first range of addresses is complete; and

repeating said reading and writing for additional ranges of addresses, until all legs of the mirrored data volume are consistent, and

wherein said processing the access requests includes processing the input/output requests in the overlap queue that are outside the first range of addresses during said read and writing to the first range of addresses.

5. A method as recited in claim 4, further comprising:

detecting failure of a storage device storing at least part of a leg of the mirrored data volume;

replicating the leg of the mirrored data volume using the mirror revive process.

6. At least one computer readable medium storing at least one program embodying a method of maintaining mirror consistency of data volumes in a cluster of computer systems sharing direct read/write access to storage devices via a storage area network, said method comprising:

automatically ensuring replication of a mirror leg in response to detection that a failed process was writing to a mirrored data volume;

accepting access requests to the mirrored data volume while reading data from an intact mirror leg and writing the data back to the mirrored data volume; and

processing the access requests that do not interfere with the creation of a replacement mirror leg while postponing processing of interfering access requests until there is no interference.

7. A method of establishing a new cluster membership of computer system nodes sharing direct read/write access to storage devices via a storage area network and a cluster operating system, comprising:

transmitting version tags for at least one subsystem of the cluster operating system from each node of a prospective membership to a leader node when establishing the nodes available for cluster membership; and

transmitting version information for all of the nodes with a proposed cluster membership from the leader node to all other nodes in the proposed cluster membership.

8. A method as recited in claim 7, further comprising communicating between the at least one subsystem on at least two computer system nodes based on the version information.

9. At least one computer readable medium storing at least one program embodying a method of establishing a new cluster membership of computer system nodes sharing direct read/write access to storage devices via a storage area network and a cluster operating system, comprising:

transmitting version tags for at least one subsystem of the cluster operating system from each node of a prospective membership to a leader node when establishing the nodes available for cluster membership; and

transmitting version information for all of the nodes with a proposed cluster membership from the leader node to all other nodes in the proposed cluster membership.

10. A method of operating a cluster of computer system nodes sharing direct read/write access to storage devices via a storage area network, comprising:

requesting a token by a client node from a metadata server node for a file prior to performing a required access to the file;

waiting for a response to said requesting;

holding the token at the client node upon receipt from the metadata server node;

releasing the token at the client node upon completion of the required access to the file; and

interrupting said waiting to check on status of at least one of data and node availability, in response to detection of a change in location of the metadata server.

11. At least one computer readable medium storing at least one program embodying a method of operating a cluster of computer system nodes sharing direct read/write access to storage devices via a storage area network, said method comprising:

requesting a token by a client node from a metadata server node for a file prior to performing a required access to the file;

waiting for a response to said requesting;

holding the token at the client node upon receipt from the metadata server node;

releasing the token at the client node upon completion of the required access to the file; and

interrupting said waiting to check on status of at least one of data and node availability, in response to detection of a change in location of the metadata server.

12. A cluster of computer systems, comprising:

storage devices storing at least one file;

a storage area network coupled to said storage devices;

at least one metadata server node, coupled to said storage area network metadata client nodes, coupled to said storage area network, sharing direct read/write access to said storage devices by sending a token request from said at least one metadata server node for the at least one file prior to performing a required access to the at least one file, waiting for a response to the token request, holding at least one token upon receipt from said at least one metadata server node, releasing the at least one token upon completion of the required access to the file and interrupting the waiting to check on status of at least one of data and node availability, in response to detection of a change in location of said at least one metadata server node.