5.06.2011

Yet another RMAN quiz: What do you do in this situation?

I will surely write a detailed blog entry later about the issue talking here. But for now, excuse me for the quiz format blog entry.
A few days ago, I was trapped into a very tricky RMAN restore situation for one of our Oracle 10g (10.2.0.4) RAC databases and would like to get your perspective over the issue. Al right, here is the QUIZ for you.


Took an RMAN offline backup to tape with 5 channels. (DB running in noarchive log mode)
The database has around 22 datafiles.
dropped the database, including the controlfiles.
Restore the controlfile from the backupset followed by full database restore.

Do you think the restore is going to finish without any issues?
What sort of issues do you anticipate with the above situation?

By the way, no controlfile auto backup was set on the RMAN.

Updates on 8/May/2011
A lot of curiosity about the quiz has been generated in the Oracle community and many DBAs indeed tried their hands giving various solutions here and at linkedIn discussions.
Just to add more spice to the curiosity, let me tell you guys that I restored the controlfile from the backuppiece and followed by complete database restore. However, when I restored the entire database, to my surprise, only 4 data files were restored from the last backup and 18 datafiles were restored last but one backup sets. When I query the rman backup, it only showed 4 datafiles backup information for the last backup, of course there were older backups info too. What has astonished me is, despite the complete successful backup operations, the controlfile got only 4 datafiles backup info for that date.
Any wild guess why ?????



Regards,

Jaffar









6 comments:

Ronald Rood said...

Hi Jaffar,
first, it's a bit strange combination: RAC, offline, noarchivelog.
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Years ago I had a similar situation, no RAC, offline, nocatalog, archivelog and the need to recover until crash time. A nice one for the next round.
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In this situation, no catalog (I assume), no snapshot control file, there is not much that RMAN can use to find what to restore from where. If you have the backup log, you can restore the files from the backup pieces by restoring them manually in the order they were listed in the backup log. The database is consistent after the restore.

maclean said...

First , you have to restore the controlfile from backup. You may ask the backup software vendor help you to find the controlfile's backup piece from their catalog. And then you could restore this controlfile from backup piece using dbms_backup_restore package, you can find this package usage by google . Hope this can help you!

The Human Fly said...

maclean, luckily, I was logging the RMAN baup operation action in a log file. Hence, I don't need to go to the netbackup administrator to know the backup piece name. By the way, just to give you a hint, there were no issues with the restore. However, I didn't get the restore that I wanted for restore.

Jaffar

Ronald Rood said...

You mean there is no controlfile in the backup. Luckily you have all the files present so a simple create controlfile is simple to do. That is no problem, just a few minutes to create the SQL for it.

Joel Garry said...

Could you have some read-only or offline tablespaces?

word: farshag

Yasir said...

Might be some tablespaces have been excluded from RMAN backup.