Replication and Locks

Can anybody post information on replication servers? What is the exact purpose of these servers: Is it for performance, or for recovery incase of a crash? In our current project we plan to use replication servers for performance ie. Data will be accessed simultaneously from these servers when a request comes. My question is whether there will be a window of inconsistency in the data between the primary database and replicate database. I heard about something called a lock propogation from primary to replicate servers. Is this possible in any of the current databases? Please reply to these questions to this e-mail id or jijo%istc206a04%st@singtel.com Regards, Joe (Work) (Singapore - 65) 462-3575 (Home) (Singapore - 65) 365-8094 (Fax ) (Singapore - 65) 467-9106