Quiescing Oracle RAC Databases

The procedure for quiescing Oracle RAC databases is identical to quiescing a noncluster database.

You use the ALTER SYSTEM QUIESCE RESTRICTED statement from one instance. You cannot open the database from any instance while the database is in the process of being quiesced. When all non-DBA sessions become inactive, the ALTER SYSTEM QUIESCE RESTRICTED statement finishes, and the database is considered as in a quiesced state. In an Oracle RAC environment, this statement affects all instances, not only the one from which the statement is issued.

To successfully issue the ALTER SYSTEM QUIESCE RESTRICTED statement in an Oracle RAC environment, you must have the Database Resource Manager feature activated, and it must have been activated since instance startup for all instances in the cluster database. It is through the facilities of the Database Resource Manager that non-DBA sessions are prevented from becoming active. Also, while this statement is in effect, any attempt to change the current resource plan is queued until after the system is unquiesced.

These conditions apply to Oracle RAC:

If you issued the ALTER SYSTEM QUIESCE RESTRICTED statement but Oracle AI Database has not finished processing it, you cannot open the database.
You cannot open the database if it is in a quiesced state.
The ALTER SYSTEM QUIESCE RESTRICTED and ALTER SYSTEM UNQUIESCE statements affect all instances in an Oracle RAC environment, not only the instance that issues the command.

Note:

You cannot use the quiesced state to take a cold backup. This is because Oracle AI Database background processes may still perform updates for Oracle AI Database internal purposes even while the database is in quiesced state. In addition, the file headers of online data files continue to look like they are being accessed. They do not look the same as if a clean shutdown were done. You can still take online backups while the database is in a quiesced state.