Importance

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Abstract

A shared persistent memory (e.g., disk) file system provides persistent memory block allocation with multiple redo logging of memory blocks. The file system employs a three part block state indicator (V,A,U). V is a volume indication. A is allocation sequence indication. U is update sequence number indication. The file system (a) generates indication of the allocation sequence in the allocation map in a manner free of initially reading the block from storage memory, (b) records the indication of volume, allocation sequence and update sequence in an entry of the transaction log of the requesting computer node, and (c) sets indications of volume, allocation sequence and update sequence on the subject block in storage memory. Subsequent transactions on the subject block, by the requesting node are recorded in respective entries in the transaction log. Each respective entry reflects state of the subject block by indicating in the block state indicator the volume, allocation sequence and order of update sequence. The file system includes redo recovery means for updating blocks in the storage memory upon a failure in the computer system. For each block being updated, the recovery means utilizes one transaction log and the block state indicators recorded therein corresponding to indications of volume and update sequence in the block in storage memory.

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First Claim