The RMU Backup command copies information contained in a database
to a file. It provides a number of options that allow you to
determine the following:
o Whether to perform a parallel backup operation.
When you specify a parallel backup operation, you must back up
to tape or multiple disks. The Parallel Backup Monitor allows
you to monitor the progress of a parallel backup operation.
o Whether to back up the database to disk or tape.
o The extent (how much of the database) to back up.
The backup operation uses a multithreaded process to optimize
the performance of the backup operation. See the Oracle Rdb
Guide to Database Maintenance for a complete description of how
multithreading works.
A parallel backup operation, in addition to using multithreaded
processes, uses a coordinator executor and multiple worker
executors (subprocesses) to enhance the speed of the backup
operation. You can also direct each worker executor to run on
a different node within a cluster to further enhance the speed
of the operation. You must have Oracle SQL/Services installed and
running to perform a parallel backup operation.
See the Oracle Rdb Guide to Database Maintenance for information
on when a parallel backup operation is most useful.
Use the Parallel qualifier to indicate to Oracle RMU that you
want to perform a parallel backup operation. Use the Noexecute
and List_Plan qualifiers to generate a Backup plan file. A Backup
plan file records the backup options and specifications you enter
on the command line in a text file. You can edit this text file
to fine-tune your parallel backup operation and execute it, as
needed, with the RMU Backup Plan command. Use the Statistics
option to the Parallel qualifier if you want to monitor the
progress of the parallel backup operation with the Parallel
Backup Monitor. See the description of the Parallel, List_Plan,
and Noexecute qualifiers, and the RMU Backup Plan command for
details.
You cannot use the Parallel Backup Monitor to monitor the
progress of a non-parallel backup operation. However, you can
achieve a close approximation of this by specifying the Executor_
Count=1 and the Statistics options with the Parallel qualifier.
This results in a parallel backup operation with one executor
and one controller that you can monitor with the Parallel Backup
Monitor.
Both parallel and non-parallel backup operations allow you to
perform different types of backup operations with respect to the
portions of the database to be backed up, as described in RMU
Backup Options.
Table 4 RMU Backup Options
Storage Area Selection
Database
Page Complete By-Area
Selection (All Areas) (Selected Areas)
Full Copies the database root Copies the database
(.rdb) file and all the root (.rdb) file and
database pages in all backs up only the
the storage areas in the database pages in the
database. This is the storage areas that you
default backup operation. specify on the backup
Note that you must use command line. All the
this type of backup prior storage areas in the
to upgrading to a newer database are backed
version of Oracle Rdb. up only if you specify
Because this is the them all (or perform
default operation, no a full and complete
qualifiers are needed to backup operation). Use
specify a full backup. the Include or Exclude
qualifiers to specify
the storage areas for
a full by-area backup
operation.
Incremental Copies all database pages Copies the database
that have been updated root (.rdb) file and
since the latest full only the database
backup operation and pages for the
the database root file. specified storage
Use the Incremental (or areas that have
Incremental=Complete) changed since the
qualifier to specify an latest full backup
incremental and complete operation. Use the
backup operation. Include or Exclude
qualifier along with
the Incremental=By_
Area qualifier
to specify an
incremental, by-area,
backup operation.
Oracle Corporation recommends that you use a full backup
operation to back up a database if you have made changes in the
physical or logical design. Performing an incremental backup
operation under these circumstances can lead to the inability to
recover the database properly.
If you choose to perform a by-area backup operation, your
database can be fully recovered after a system failure only
if after-image journaling is enabled on the database. If your
database has both read/write and read-only storage areas but does
not have after-image journaling enabled, you should do complete
backup operations (backup operations on all the storage areas
in the database) at all times. Doing complete backup operations
when after-image journaling is not enabled ensures that you can
recover the entire database to its condition at the time of the
previous backup operation.
When a full backup file is created for one or more storage
areas, the date and time of the last full backup file created
for those storage areas (as recorded in the backup (.rbf) file)
is updated. You can display the date and time of the last full
backup operation on each of the storage areas in a database by
executing an RMU Dump command with the Header qualifier on the
latest backup (.rbf) file for the database. The date and time
displayed by this command is the date and time of the last full
backup operation performed for the area.
Note that an incremental backup operation on a storage area does
not update the date and time for the last full backup operation
performed on the storage area that is recorded in the backup
file.
In the event of subsequent damage to the database, you can
specify backup files in an RMU Restore command to restore the
database to the condition it was in when you backed it up.
The RMU Backup command writes backup files in compressed format
to save space. Available or free space in the database root
(.rdb) file and on each database page in a storage area (.rda)
file is not written to the backup file.
NOTE
Use only the RMU Backup command to back up all Oracle Rdb
databases. Do not back up a database by using any other
method (such as the DCL BACKUP command). The database root
of a database is updated only when the RMU Backup command is
used.
For detailed information on backing up a database to tape, see
the Oracle Rdb Guide to Database Maintenance.