#
# Multiple entries with the same $ORACLE_SID are not allowed.
##
+ASM1:/u01/app/oracle/product/11.1.0/db_1:Y
rac:/u01/app/oracle/product/11.1.0/db_1:Y
Redo Logs in a RAC Environment
As with a single-node instance, online redo logs are used for instance recovery in a RAC
environment; each instance in a RAC environment has its own set of online redo log files that
are used to roll forward all information in the redo logs and then roll back any uncommitted
transactions initiated on that node using the undo tablespace.
Even before the failed instance has restarted, one of the surviving instances detects the instance
failure and uses the online redo log files to ensure that no committed transactions are lost; if this
process completes before the failed instance restarts, the restarted instance does not need instance
recovery. Even if more than one instance fails, all that is required for instance recovery is one
remaining node. If all instances in a RAC fail, the first instance that starts up will perform instance
recovery for the database using the online redo log files from all instances in the cluster.
If media recovery is required and the entire database must be recovered, all instances except
for one must be shut down and media recovery is performed from a single instance. If you are
recovering noncritical database files, all nodes may be up as long as the tablespaces containing
the files to be recovered are marked as OFFLINE.
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