Patent ID: 9563633
Date: 2017-02-07
CPC Classifications: G06F

Claim:
1. A method for pruning unused blocks from a versioned image backup of a source storage that is stored in a sparse storage, the method comprising: identifying a versioned image backup of a source storage that is stored in a sparse storage, the sparse storage supporting versioning using a snapshot process, the sparse storage storing first and second versions of the versioned image backup representing states of the source storage at successive first and second points in time, respectively; during a retention process, deleting the first version of the versioned image backup from the sparse storage; identifying a first set of blocks to include blocks that are indicated as allocated in a second file system block allocation map (FSBAM) that indicates blocks that were allocated in the source storage at the second point in time; identifying a second set of blocks to include blocks that are indicated as allocated in a second sparse storage block allocation map (SSBAM) that indicates the blocks that are allocated in the sparse storage for the second version of the versioned image backup; determining a third set of blocks that are included in the second set of blocks but are not included in the first set of blocks; and after the retention process, trimming the third set of blocks from the second version of the versioned image backup that is stored in the sparse storage.