 |
|
Oracle Backing
Up the Flash Recovery Area
Oracle Tips by Burleson Consulting |
This
is an excerpt from "Oracle 10g New Features for Administrators" by
Ahmed Baraka.
In order to back up the flash recovery area itself
using RMAN, you must set CONFIGURE BACKUP OPTIMIZATION to ON.
You can back up the flash recovery area only to a
tape device using these backup commands:
BACKUP RECOVERY AREA
o This command backs up all flash recovery files
in the current or previous flash recovery area destinations.
o It backs up only those files that have never
been backed up to tape before.
o The files that the command will back up include
full backups, incremental backups, control file autobackups,
archive logs, and datafile copies.
BACKUP RECOVERY FILES - This command backs up all
the files that the BACKUP RECOVERY AREA command does, but from all
areas on your file system, not just from the flash recovery area.
BACKUP RECOVERY FILE DESTINATION - Use this command
to move disk backups created in the flash recovery area to tape.
Note: Neither of the two commands, BACKUP
RECOVERY AREA or BACKUP RECOVERY FILES, will back up any permanent
files or the flashback logs in the flash recovery area.
Managing the Flash Recovery Area - Space Management
If you ever receive the out-of-space warning (85)
and critical alerts (97) because of space pressure in you flash
recovery area, you have the following options:
o Consider changing your backup retention and
archive log retention policies.
o Increase the size of the
DB_RECOVERY_FILE_DEST_SIZE parameter to allocate more space to
your current flash recovery area.
o Use the BACKUP RECOVERY AREA command in the RMAN
to back up the contents of the flash recovery area to a tape
device.
o Use the RMAN to delete unnecessary backup files.
The RMAN commands CROSSCHECK and DELETE EXPIRED come in handy
during this deletion process.
Data Dictionary Views
V$RECOVERY_FILE_DEST
This view is the main source and contains the
following columns:
|
SPACE_LIMIT |
how much space has been
allocated to the flash recovery area |
|
SPACE_USED |
space occupied |
|
SPACE_RECLAIMABLE |
how much space you can reclaim
by getting rid of obsolete and redundant files in the flash
recovery area. |
|
NUMBER_OF_FILES |
number of files |
V$FLASH_RECOVERY_AREA_USAGE
This view provides information about the flash
recovery area disk space usage. Following is its main columns:
FILE_TYPE - the type of the file and can have
any of the following values:
controlfile, onlinelog,
archivelog, backuppiece, imagecopy, flashbacklog
PERCENT_SPACE_USED - This represents the disk space used by the file
type, in percentage.
PERCENT_SPACE_RECLAIMABLE - this represents the
percentage of disk space reclaimable from the file type after
deleting any obsolete or redundant files, and files backed up to a
tertiary device.
Flash Recovery Area Columns in Other Views
The Yes/No column IS_RECOVERY_DEST_FILE is added to
some dictionary views to indicate whether the file was created in
the flash recovery area. It exists in V$CONTROLFILE, V$LOGFILE,
V$ARCHIVED_LOG, V$DATAFILE_COPY, V$BACKUP_PIECE.
Moving the Flash Recovery Area
ALTER SYSTEM SET
DB_RECOVERY_FILE_DEST='/u01/app/oracle/new_area
' SCOPE=BOTH
Eventually, Oracle will delete all the transient
files from the previous flash recovery area location, when each of
them become eligible for deletion. However, if you want to move your
current permanent files, transient files, or flashback logs to the
new flash recovery area, you can do so by using the standard
file-moving procedures.
 |
If you like Oracle tuning, see the
book "Oracle
Tuning: The Definitive Reference", with 950 pages of tuning
tips and scripts.
You can buy it direct from the publisher for 30%-off and get
instant access to the code depot of Oracle tuning scripts. |
