Patent ID: 8271447

Claim:
A method comprising: providing data protection to data in a first volume at a first data protection appliance by storing a copy of the data in a second volume using a second data protection appliance; tracking changes between data locations in the first volume and the second volume using a delta marking stream (DMS), the DMS comprising a stream of metadata comprising input/output completed to the first volume which have not yet been applied to a replication journal and input/output applied to the replication journal which have not been completed to the second volume, the replication journal comprising a DO stream, an UNDO stream, a DO metadata stream and an UNDO metadata stream; receiving, at the first data protection appliance, metadata not yet committed to the DMS; mirroring the metadata at a third data protection appliance in a same cluster as the first data protection appliance, wherein the same cluster comprises the first data protection appliance and the third data protection appliance; committing the metadata to the DMS; removing the metadata from the third data protection appliance if the metadata is committed to the DMS determining if the acquiring of the metadata at the third data protection appliance is successful; moving the metadata to the DMS and moving the system to stable mode if acquiring the metadata is successful; receiving a request to recover the metadata; and performing a full sweep on the first and second volumes if in a fragile mode.