Database Reference
In-Depth Information
They are two different things. Online or offline backups simply indicate the state of the
database (running or not) when the backup occurs.
A consistent or inconsistent backup refers to the temporal state of the data in the data-
base datafiles. An inconsistent backup can occur when the database is running or shut
down. A consistent database backup can only occur after the database is shut down nor-
mally (e.g.,
shutdown immediate
).
A database in NOARCHIVELOG mode can be backed up only when the database is in
a consistent state. As a result, any attempt to restore an inconsistent database backup taken
in NOARCHIVELOG mode will fail. A database in ARCHIVELOG mode will be able to
recover using either a consistent or inconsistent database backup.
RMAN Offline Backups
We discussed manual offline backups in Chapter 1. Offline backups in RMAN are not much
different except that you use the RMAN interface to actually do the backup rather than an
OS file-copy utility. You will still need to close the database, but your backup will be done
with the database in mount mode rather than completely shut down. No parameter-file
adjustments are required for an RMAN offline backup.
We recommend that you configure and use the FRA (discussed earlier
in this chapter) even if you are doing offline backups. This makes for a
standardized backup location and also allows the Oracle database to
manage the overall backup space utilization more efficiently.
To perform an offline backup of your database with RMAN, follow these steps:
1.
Start the RMAN client.
2.
Shut down the database from the RMAN client, SQL*Plus, or OEM.
The shutdown should be a consistent shutdown, so use the
SHUTDOWN
,
SHUTDOWN
IMMEDIATE
, or
SHUTDOWN TRANSACTIONAL
command.
3.
Start up the database in mount mode using the
STARTUP MOUNT
command.
4.
Back up the database with the RMAN
BACKUP
command:
RMAN>backup database;
5.
When the backup is complete, open the database with the
ALTER DATABASE OPEN
command.
RMAN Online Backups
For online backups in RMAN, the database must be configured in ARCHIVELOG mode
(see Chapter 1 for more on configuring the database for ARCHIVELOG-mode operations).
Once the database is configured properly and RMAN is configured properly (as discussed
earlier in this chapter), you can do online backups.
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