Abstract: A mirror destination storage server receives mirror update data streams from several mirror source storage servers. Data received from each mirror is cached and periodic checkpoints are queued, but the data is not committed to long-term storage at the mirror destination storage server immediately. Instead, the data remains in cache memory until a trigger event causes the cache to be flushed to a mass storage device. The trigger event is asynchronous with respect to packets of at least one of the data streams. In one embodiment, the trigger event is asynchronous with respect to packets of all of the data streams.

Abstract: Differences between data objects stored on a mass storage device can be identified quickly and efficiently by comparing block numbers stored in data structures that describe the data objects. Bit-by-bit or byte-by-byte comparisons of the objects' actual data need only be performed if the block numbers are different. Objects that share many data blocks can be compared much faster than by a direct comparison of all the objects' data. The fast comparison techniques can be used to improve storage server mirrors and database storage operations, among other applications.