HASH VALUE COMPARISON DURING CRASH-TOLERANT INCREMENTAL CHANGE TRACKING BETWEEN BACKUPS OF A SOURCE STORAGE

摘要

Hash value comparison during crash-tolerant incremental change tracking between backups of a source storage. In one example embodiment, a method includes assigning each block in a source storage into one of multiple zones, creating a nonvolatile zone map, tracking each of the zones that is changed between a first point in time and a second point in time, identifying, as potentially changed zone blocks, the blocks in the source storage assigned to any zone marked as changed in the nonvolatile zone map, identifying, as potentially outdated backup blocks, the most recently backed-up blocks in one or more prior backups that correspond to the potentially changed zone blocks, calculating source hash values of the potentially changed zone blocks, calculating backup hash values of the potentially outdated backup blocks, and comparing the source hash values to the backup hash values to determine which blocks in the source storage actually changed.