Clustered filesystem

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, by
• 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;
• 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.

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, maintaining mirror consistency during normal operation and replicating a mirror leg upon detecting failure of a first one of said computer system nodes that was writing to the at least one mirrored data volume, while continuing to accept access requests to the at least one mirrored data volume from remaining ones of said computer system nodes.

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.