Patent ID: 8392675

Claim:
A method, comprising: generating a current persistent, point-in-time image (PPI) of a data management module corresponding to a set of blocks, the data management module being associated with an active map, wherein the active map is representative of a current allocation status of the set of blocks; generating a PPI map that corresponds to the current PPI, wherein the PPI map is representative of allocation status of the set of blocks at a time at which the current PPI was generated; detecting, for a particular block of the set of blocks, divergence in allocation status between the active map and the PPI map; and in response to detecting the divergence for the particular block, updating allocation status of the particular block in a summary map, the summary map indicative of allocation status of each block of the set of blocks based on a plurality of PPI maps, wherein the plurality of PPI maps correspond to PPIs generated at different points in time, and wherein the summary map and the active map are used to determine an allocation status of one or more blocks of the set of blocks as being allocated or free when making a write allocation decision.