Performing Oracle User-Managed Backups - OCP: Oracle Database 12c Administrator Certified Professional - page 25

Performing Database Restricted-Mode Operations
Sometimes it's nice to have the house to yourself, isn't it? Oracle allows you the equivalent
of having the house to yourself when you put the database in restricted mode. When the
database is in restricted mode, only those with the restricted session privilege can access
it. Since DBA accounts have restricted session privileges, this means you can log into the
database and do your work, feeling secure that other users won't get in and cause problems.
You may find that during certain recovery operations a restricted session will help when
you need to get into the database to perform some DBA-related activities but you don't
want other users to log in yet.
To open the database in restricted mode, you issue the STARTUP RESTRICT command. If
your database is already open, you can put it in restricted mode with the ALTER DATABASE
ENABLE RESTRICTED SESSION command. This will not impact existing users, but new users
will not be able to connect unless they have the restricted session privilege. To disable the
restricted session and allow users to connect to the database, use the ALTER DATABASE
DISABLE RESTRICTED SESSION command.

Performing Backup and Recovery Operations and Getting Database Status
So, what kind of operations would you perform given the different open or closed combina-
tions of the database? Here are some examples:

Operations while the instance is down and the database is not open:

Copy the spfile to a pfile

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Copy the pfile to an spfile

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Perform manual cold backups

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Operations while the instance is open and the database is not open:

Create a database

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Create a database control file

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Restore the database control file or spfile from RMAN

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Operations while the instance is mounted and the database is not open:

Cold backup with RMAN

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Recovery of critical data files ( SYSTEM , UNDO tablespaces)

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Offline recovery of entire database

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Operations while the instance is mounted and the database is open:

Online data file or tablespace recovery of noncritical tablespaces

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Online backups of the database

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