Hi,

All these days i was under the impression that one database is
one instance. Recently, i came across some information that tells
that one database can have multiple instances running parallely.
Can anyone shed some light on this.
Some information or links would be of great use

Thanks

See this link:

http://asktom.oracle.com/pls/ask/f?p...D:444613412425

It's when you have Oracle Parallel Server or RAC (lately). Two or more instances (SGA + background processes all together) run against the same set ot datafiles, redo log files,etc. (database).

Each instance have access to the same data - unlike as DB2 and SQL Server, where the data is partitioned (federated clustering).


Hope that helps,

clio_usa - OCP - DBA