Patent ID: 7711986

Claim:
A method comprising: receiving a write transaction by a primary device; transmitting the write transaction from the primary device to N backup devices, where N is greater than one; by each backup device, recording the write transaction to a local redo log stored at a high-performance storage; transmitting a notification to the primary device that the write transaction has been recorded; after the primary device has received notifications from M of the N backup devices, where M is less than N, committing the write transaction by the primary device; after committing the write transaction by the primary device, recording the write transaction by the primary device to a low-performance storage, such that the write transaction is recorded by the primary device to the low-performance storage after the M of the N backup devices have each recorded the write transaction to the local redo log stored at the high-performance storage, wherein the low-performance storage has a lower performance than a performance of each high-performance storage; in response to the primary device incurring a fault, one of the N backup devices becoming a new primary device, such that remaining of the N backup devices are N−1 backup devices; the new primary device determining which of the N backup devices has a newest local redo log; where the backup device having the newest local redo log is one of the N−1 backup devices, the new primary device requesting the backup device having the newest local redo log to send the newest local redo log to all other of the N backup devices; where the backup device having the newest local redo log is the new primary device, the new primary device sending the newest local redo log to the N−1 backup devices; and, by each of the N backup devices except the backup device having the newest local redo log, receiving the newest local redo log from the backup device having the newest local redo log, and updating the local redo log to a same state as the newest local redo log received.