Disclosed herein is a system and method for checking and maintaining consistency of blocks stored in a virtual disk with a content based read cache (CBRC). When blocks are written to the cache and virtual disk, a hash is computed for the block and stored in a digest file on the virtual disk. In the background, each block is obtained from the virtual disk, its hash is recomputed, and the hash is compared to the stored hash in the digest file. If the comparison indicates a mismatch, then an error is reported.