Patent ID: 6895416

Claim:
A method for checkpointing a filesystem of a distributed-memory parallel supercomputer comprising a node that accesses user data on the filesystem, the filesystem comprising an interface that is associated with a disk for storing the user data, the method comprising the steps of: (a) informing the node and the interface to pause new file operations and complete outstanding file operations on the filesystem in order to take a checkpoint of the filesystem; (b) directing the interface to take the checkpoint of the associated disk; (c) the taking of the checkpoint comprising a step of clearing: (i) a recently written file allocation table (WFAT) for maintaining information regarding the user data written to the disk since the previously taken checkpoint; (ii) a recently deleted file allocation table (DFAT) for maintaining information regarding the user data deleted from the disk since the previously taken checkpoint; (d) informing the node and the interface that they may resume new file operations on the filesystem; and (e) within actions on the filesystem, recording in the WFAT and DFAT information required to rollback the filesystem to the previously taken checkpoint;