Secondary database server

A secondary database server or SDS is a database server that is kept in synchronisation with the main database so that if the main database goes offline, the secondary database server can be used instead. This is important for a live system that must be online 24 hours a day, and most DBMS systems that support SDSs are capable of automatically detecting and switching to the secondary server within seconds of the main server going offline. The secondary database server can also be used to run read-only queries to take load off the first database server and increase system performance.