Databases Reference
In-Depth Information
Loss
of
critical
datafiles
: If a technically defined critical datafile is
lost, there is no way to start the database, and the file must be restored
and fully recovered for the database to be open.
Loss
of
non-critical
datafiles
: In this case, the database can be opened
as long as the missing datafiles are declared offline. A recover operation
can take place on the specific missing database files once they have been
restored from a valid backup.
The recovery manager command used to perform the restore and recover operations
are precisely
RESTORE
and
RECOVER
. They have a simple syntax. The emphasis in this
topic is on the RMAN features rather than the
rman
syntax.
Backup compression
If limited disk space is available, or a backup across a network environment imposes
bandwidth restrictions, or if the backup is to be transported on media with a limited
storage capacity, then a compressed backup is a good option.
Fast backup compression
The compressed backup can be directly configured as an option for the
CONFIGURE
CHANNEL
command.
CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO COMPRESSED
BACKUPSET;
Once the backup is performed, it will be done in a compressed format.
The compression can also be configured in a non-persistent way, it can be specified
directly as a command option:
BACKUP AS COMPRESSED BACKUPSET DATABASE PLUS ARCHIVELOG;
In order for the DBA to recover from a compressed backup, they just need to issue
the regular
RESTORE/RECOVER
commands. There are no specific parameters required
to recover from a compressed backup set.
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