A configuration file specifies a percentage value of data to validate. A synthetic full backup image of a source volume on cloud storage is accessed. The synthetic full backup is created by merging changed blocks of an incremental backup with another previous backup. A bitmap specifying locations of the changed blocks is examined. A region on the synthetic full backup beginning at a location corresponding to an initial changed block and ending at a location corresponding to a last changed block according to the bitmap is identified. The region is partitioned into a set of portions. Each portion is validated by randomly selecting blocks in a respective portion to validate. The validating of the respective portion continues until an amount of data validated in the respective portion reaches a size equal to the percentage value of a size of the incremental backup divided by a number of portions.