Consolidating decremental backups in a decremental backup chain

摘要

Consolidating decremental backups in a decremental backup chain. In one example embodiment, a method for consolidating decremental backups in a decremental backup chain includes identifying a decremental backup chain that includes multiple decremental backups of a source storage and a base backup of the source storage, identifying, for consolidation, a sequential set of decremental backups in the multiple decremental backups, identifying a set of oldest blocks from the sequential set of decremental backups for unique block positions of blocks included in the sequential set of decremental backups, and creating a consolidated decremental backup that includes the set of oldest blocks.

主权项

1. A method for consolidating decremental backups in a decremental backup chain, the method comprising:
identifying a decremental backup chain that includes multiple decremental backups of a source storage and a base backup of the source storage; identifying, for consolidation, a sequential set of decremental backups in the multiple decremental backups; identifying a set of oldest blocks from the sequential set of decremental backups for unique block positions of blocks included in the sequential set of decremental backups; and creating a consolidated decremental backup that includes the set of oldest blocks, wherein the identifying of the set of oldest blocks includes:
retrieving one or more file system block allocation maps (FSBAMs) for points in time represented by the consolidated decremental backup and represented by any of the other decremental backups in the decremental backup chain that depend on the consolidated decremental backup, the retrieving of the one or more FSBAMs including, for each FSBAM, searching forward in the decremental backup chain, from the decremental backup in the decremental backup chain that represents the point in time of the FSBAM, for the first block for each of one or more block positions that make up the FSBAM in order to reconstruct the FSBAM;identifying free blocks, corresponding to block positions that are indicated as being free in all of the FSBAM(s), in the set of oldest blocks; andpruning the free blocks out of the set of oldest blocks.