wow, you should write a book on this stuff :-) the san would be synchronous writes. So If i can try to put it simply - it would work that way, but dataguards on the face of it seems the better, cheaper solution ? On 6/1/05, Carel-Jan Engel <cjpengel.dbalert@xxxxxxxxx> wrote: > David, >=20 > Is the SAN replicating synchronously or asynchronously? > Data Guard needs less bandwidth than storage based replication. Most of t= he > times SAN's are configured to replicate asynchrously. Just think of the > amount of data that needs to be sent over when storage is replicated: Red= o > writes (all members), archive copies (maybe also redundant?), the writes = to > data files, and the updates of the controlfile. Mind that storage based > replication is often disk block based, or even disktrack-based! You can > imagine what amount of data needs to go through the pipe for that. Compar= e > that with just sending the redo entries with Data Guard. The standby site > will take care of applying them, writing to data files and performing the > archive job locally.=20 > -- //www.freelists.org/webpage/oracle-l