This chapter explains features of Oracle multi-instance architecture which differ from an Oracle server in exclusive mode. DBWR processes are shown writing data, users reading data. An Oracle instance can be started on one or more nodes in the network.
All instances share the same datafiles and control file.
Each instance has its own set of redo log files. On some MPP platforms, a redo server exists so that only one set of redo logs is necessary for the whole OPS system. Archived logs are private, but must be accessible to all instances for media recovery. All instances can execute transactions concurrently against the same database, and each instance can have multiple users executing transactions. Row level locking is preserved.