You can
configure a device to be used by RMAN using the CONFIGURE DEVICE TYPE command.
Parallelism
Parallelism
is the number of streams of data that can be used to read from and write to the
device. This effectively causes that number of channels to be allocated when
the device is used by RMAN. For example, if a media manager has two tape drives
available, then parallelism 2 would allow both tape drives to be used
simultaneously for BACKUP commands using that media manager. Parallelism for
the disk device type is also useful, when you want to spread out a backup over
multiple disks.
Specify the
parallelism to be used on the device using the PARALLELISM clause, like this:
CONFIGURE DEVICE TYPE <device>
PARALLELISM <n>
where <n> is
the parallelism value.
Backup
Type
The output
of the backup can be either a backup set or an image copy. Configure the
default for a device type using the BACKUP TYPE TO clause. Specify BACKUP SET
for a backup set and COPY for an image copy.
Compression
Specify the
COMPRESSED keyword after the BACKUP TYPE TO clause to specify that backups to
this device are to be compressed. Compression results in smaller backup files.
Configuring
and Allocating Channels for Use in Backups
Choose from
the following options for configuring channels and executing backups:
•
Configure
automatic channels with the CONFIGURE command, and then issue the BACKUP
command at the RMAN prompt or within a RUN block.
•
Manually
allocate channels with the ALLOCATE CHANNEL command within a RUN block, and
then issue BACKUP commands.
Configuring
Backup Optimization
If you
enable backup optimization, the BACKUP command skips backing up files when the
identical files have already been backed up to the specified device type.
If RMAN
determines that a file is identical and it has already been backed up, then it
is a candidate to be skipped. However, RMAN performs further checking to
determine whether to skip the file, because both the retention policy and the
backup duplexing feature are factors in the algorithm that RMAN uses to
determine whether there are sufficient backups on the specified device type.
