1. One or more computer storage media having computer-executable instructions embodied thereon that, when executed, cause a computing device to perform a method of ensuring consistency across a replicated data storage system, the method comprising: receiving, at a secondary data store, one or more messages from a primary data store, said one or more messages comprising checkpointing information and a checksum for a range of data in a corresponding checkpoint at the primary data store; creating a local checkpoint in accordance with the checkpointing information; calculating a local checksum over the range of data in the local checkpoint; comparing the local checksum with the received checksum to determine if a discrepancy exists for the range of data between data stored at the primary data store and data stored at the secondary data store.