RMAN Hot Backup Script

The following unix shell script will do a full RMAN hot backup to your database and will copy the backup files compressed to the directory you will specify. This is a hot-backup, and the database must to be in ARCHIVELOG mode for this to work.

A backup retention policy with a recovery window of 2 days is defined in this script. With this retention policy RMAN will keep archive logs and backup files necessary to recover to any point of time within those 2 days in the recovery window. Older backups and archivelogs not needed to satisfy this retention policy will be automatically deleted by this script. No RECOVERY CATALOG is being used with this script, instead database controlfiles are used to record the RMAN repository information.

Make sure you set the rman CONFIGURE CONTROLFILE AUTOBACKUP parameter to ON in in RMAN in order to take extra backups of the controlfile and spfile (RMAN will not backup init.ora files) as extra protection.

This script will delete obsolete backups and not needed archive logs from the disks only after a successful backup. This means you don’t need to set up cronjobs or manually delete not needed backups. This is the beauty of using RMAN. It does this automatically with the commands: “…DELETE NOPROMPT OBSOLETE;…” and “…DELETE NOPROMPT EXPIRED BACKUP…” See last lines in the script.

The RMAN hot backup script rman_backup.sh

# Declare your ORACLE environment variables
export ORACLE_SID= (put your SID here)
export ORACLE_BASE= (put your ORACLE BASE here)
export ORACLE_HOME= (put your ORACLE_HOME here)
export PATH=$PATH:${ORACLE_HOME}/bin

# Start the rman commands
rman target=/ << EOF
CONFIGURE CONTROLFILE AUTOBACKUP ON;
CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO ‘/(put backup directory here)/autobackup_control_file%F’;
CONFIGURE RETENTION POLICY TO RECOVERY WINDOW OF 2 DAYS;
run {
ALLOCATE CHANNEL RMAN_BACK_CH01 TYPE DISK;
CROSSCHECK BACKUP;
BACKUP AS COMPRESSED BACKUPSET DATABASE FORMAT ‘/(put backup directory here)/databasefiles_%d_%u_%s_%T’;
sql ‘ALTER SYSTEM ARCHIVE LOG CURRENT’;
BACKUP AS COMPRESSED BACKUPSET ARCHIVELOG ALL FORMAT ‘/(put backup directory here)/archivelogs_%d_%u_%s_%T’ DELETE INPUT;
BACKUP AS COMPRESSED BACKUPSET CURRENT CONTROLFILE FORMAT ‘/(put backup directory here)/controlfile_%d_%u_%s_%T’;
CROSSCHECK BACKUP;
DELETE NOPROMPT OBSOLETE;
DELETE NOPROMPT EXPIRED BACKUP;
RELEASE CHANNEL RMAN_BACK_CH01;
}
EXIT;
EOF
#

Note: If you run this script on a database which was being backed up using OS methods and user managed backups, initially it will fail as it will look to satisfy the ‘… ARCHIVELOG ALL…” clause. That is it will try to backup archivelogs since day 1. Well, unless you have lots of money to allocate for storage, we know that is not practical to keep all archivelogs and with OS backups usually we delete them manually according to the chosen backup retention pollicy. The script once run initially will fail like this:

Starting backup at 24-MAR-08
current log archived
using channel ORA_DISK_1
archived log /u00/arch/1_2_650282994.arc not found or out of sync with catalog
trying alternate file for archivelog thread 1, sequence 2
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of backup command at 03/24/2008 10:43:29
RMAN-06059: expected archived log not found, lost of archived log compromises recoverability
ORA-19625: error identifying file /u01/arch/1_2_650282994.arc
ORA-27037: unable to obtain file status
Linux Error: 2: No such file or directory
Additional information: 3

As you can see the script assumes that you have all archivelogs, if that is not the case (most likely), and you have been periodically deleting them ie. crontab, or manually, you can always sync the existing RMAN catalog (or controlfile) by crosschecking what is there on the disk before you run it with the following command from RMAN:

For before Oracle 9i

RMAN> change archivelog all crosscheck;

or in Oracle 9i,10g

RMAN> crosscheck archivelog all;

This will crosscheck existing archivelogs and will show you the ones which are EXPIRED and need to be deleted from the RMAN catalog, that is, they are not on the disks anymore, cause you have deleted them not using RMAN. RMAN doesn’t know this, it expects them! To delete these misleading entries from your control file you will have to run the command:

RMAN> delete expired archivelog all;

After you delete the expired archivelog records from the control file you can run the script and take your backups.

To see how a recovery is done with a backup taken with this script on a New Host with the same directory structure search this blog for RMAN Recovery.