RMAN Improvements Over Versions

Back in the days of 9iR2, RMAN was getting very popular but there were some issues with features where end-user requirements were not met to it's fullest extent. Over the next set of releases Oracle RMAN has improved on these issues and has become my favorites these days.

One of the biggest improvements in RMAN came in Oracle 10g with the introduction of block change tracking. However, there was another feature that left us longing for more. The "KEEP FOREVER" feature that would let us keep a backup forever (or until we desired) so to speak.

In Oracle 9i (9.2.0.7 to be precise), I tried to use this feature to retain my Oracle ERP 11i backups until a critical phases of the projects were complete say, CRP II or UAT etc. In 9i, when the retention was set to number of redundancies, and a copy of the database backup was meant to be kept forever, we ran into an issue when the newest nth backup will actually not happen.
In other words, If the redundancy was set at (let's say 5), and the first backup was "kept forever", then the 6th backup was not actually retained for restore. Instead the backup commands will complete successfully without the physical backup taking place. The only option, as I recall, was to keep incrementing the redundancy until the "keep forever" backup was to expire and do catalog maintenance to cleanup subsequent backups before getting back to the original redundancy requirement. To say the least, this was not very helpful.

Then in Oracle 10g, I was delighted to see that this issue was resolved but the one last nagging issue still remained with long term backups. That is the requirement to have the backup in a consistent state in order to have the archived logs deleted. If the backup was to be taken in an inconsistent state, Oracle kept every single one of archived logs for recovery. I used to wonder why this requirement was enforced as it is expected that an inconsistent backup when used for restore will be restored to a point-in-time or SCN and should be opened "resetlogs". In this case, there is no need for "all" the archives to be kept up until right this minute.

Finally, this critical issue has been answered in Oracle 11g.

Oracle 11g has introduced a new feature called a "restore point" in rman backups wherein a restore point that tracks the last SCN for a long-term inconsistent backup is maintained. Gone are the syntaxes "keep forever logs or nologs" instead we use "keep forever restore point XXX". This will provide us with the ability to delete all the archive logs generated after the long term backup thereby saving lot of space that in it's absence would be needed to maintain all the archived logs.

So with 11g, Now we can take a inconsistent backup that is long term with no overhead storage requirement for all the archived logs generated. That's great!!!

Below are the rman output for a 10g and 11g "keep forever" backup respectively.


10g Keep Forever Backup

RMAN> backup full database tag='full_keep_forever' keep forever logs;

Starting backup at 04-DEC-08
using channel ORA_DISK_1
using channel ORA_DISK_2
backup will never be obsolete
archived logs required to recover from this backup will expire when this backup expires
skipping datafile 6; already backed up 2 time(s)
channel ORA_DISK_1: starting full datafile backupset
channel ORA_DISK_1: specifying datafile(s) in backupset
input datafile fno=00004 name=C:\ORACLE\PRODUCT\ORADATA\O10203\USERS01.DBF
input datafile fno=00008 name=C:\ORACLE\PRODUCT\ORADATA\O10203\RMAN_TEST_TBS01.DBF
input datafile fno=00005 name=C:\ORACLE\PRODUCT\ORADATA\O10203\USERS02.DBF
channel ORA_DISK_1: starting piece 1 at 04-DEC-08
channel ORA_DISK_2: starting full datafile backupset
channel ORA_DISK_2: specifying datafile(s) in backupset
input datafile fno=00001 name=C:\ORACLE\PRODUCT\ORADATA\O10203\SYSTEM01.DBF
input datafile fno=00002 name=C:\ORACLE\PRODUCT\ORADATA\O10203\UNDOTBS01.DBF
input datafile fno=00003 name=C:\ORACLE\PRODUCT\ORADATA\O10203\SYSAUX01.DBF
input datafile fno=00007 name=C:\ORACLE\PRODUCT\ORADATA\O10203\NEW_RW_TBS01.DBF
channel ORA_DISK_2: starting piece 1 at 04-DEC-08
channel ORA_DISK_2: finished piece 1 at 04-DEC-08
piece handle=F:\RMANBACKUP\E3K1DTCM_1_1 tag=FULL_KEEP_FOREVER comment=NONE
channel ORA_DISK_2: backup set complete, elapsed time: 00:03:21
channel ORA_DISK_1: finished piece 1 at 04-DEC-08
piece handle=F:\RMANBACKUP\E2K1DTCK_1_1 tag=FULL_KEEP_FOREVER comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:03:38
Finished backup at 04-DEC-08

Starting Control File and SPFILE Autobackup at 04-DEC-08
piece handle=C:\ORACLE\PRODUCT\DB102\DATABASE\C-4123959065-20081204-01 comment=NONE
Finished Control File and SPFILE Autobackup at 04-DEC-08

11g Keep Forever Backup

RMAN> backup full database tag='full_keep_forever' keep forever restore point abc;

Starting backup at 04-DEC-08
current log archived

using channel ORA_DISK_1
backup will never be obsolete
archived logs required to recover from this backup will be backed up
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
input datafile file number=00002 name=C:\ORACLE\PRODUCT\ORADATA\ORA11\SYSAUX01.DBF
input datafile file number=00001 name=C:\ORACLE\PRODUCT\ORADATA\ORA11\SYSTEM01.DBF
input datafile file number=00003 name=C:\ORACLE\PRODUCT\ORADATA\ORA11\UNDOTBS01.DBF
input datafile file number=00004 name=C:\ORACLE\PRODUCT\ORADATA\ORA11\USERS01.DBF
input datafile file number=00005 name=C:\ORACLE\PRODUCT\ORADATA\ORA11\EISCAT01.DBF
input datafile file number=00006 name=C:\ORACLE\PRODUCT\ORADATA\ORA11\HYPUSER01.DBF
input datafile file number=00007 name=C:\ORACLE\PRODUCT\ORADATA\ORA11\PROD_SRC01.DBF
channel ORA_DISK_1: starting piece 1 at 04-DEC-08
channel ORA_DISK_1: finished piece 1 at 04-DEC-08
piece handle=C:\ORACLE\PRODUCT\11G\DB_1\DATABASE\11K1DTMI_1_1 tag=FULL_KEEP_FOREVER comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:02:58


current log archived
using channel ORA_DISK_1
backup will never be obsolete
archived logs required to recover from this backup will be backed up
channel ORA_DISK_1: starting archived log backup set
channel ORA_DISK_1: specifying archived log(s) in backup set
input archived log thread=1 sequence=191 RECID=31 STAMP=672593814
channel ORA_DISK_1: starting piece 1 at 04-DEC-08
channel ORA_DISK_1: finished piece 1 at 04-DEC-08
piece handle=C:\ORACLE\PRODUCT\11G\DB_1\DATABASE\12K1DTSQ_1_1 tag=FULL_KEEP_FOREVER comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01

using channel ORA_DISK_1
backup will never be obsolete
archived logs required to recover from this backup will be backed up
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
including current SPFILE in backup set
channel ORA_DISK_1: starting piece 1 at 04-DEC-08
channel ORA_DISK_1: finished piece 1 at 04-DEC-08
piece handle=C:\ORACLE\PRODUCT\11G\DB_1\DATABASE\13K1DTT9_1_1 tag=FULL_KEEP_FOREVER comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01

using channel ORA_DISK_1
backup will never be obsolete
archived logs required to recover from this backup will be backed up
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
including current control file in backup set
channel ORA_DISK_1: starting piece 1 at 04-DEC-08
channel ORA_DISK_1: finished piece 1 at 04-DEC-08
piece handle=C:\ORACLE\PRODUCT\11G\DB_1\DATABASE\14K1DTTN_1_1 tag=FULL_KEEP_FOREVER comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
Finished backup at 04-DEC-08

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