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How to recover unarchived data in case of media failure [message #540862]

Thu, 26 January 2012 06:39

hammad83
Messages: 46
Registered: June 2008
Location: Australia

Member

I have a database for which I use RMAN for backup & recovery. The database is in archivelog mode. Online redo log files are multiplexed and I have more than one destinations for archive logs. If, due to a disk crash, all data files and redo log files are gone - and I have archive logs, one member of each redo log group and a full database backup available, I can recover till the last archived log. But I want to ask that what about the transactions which were not archived at the time of media failure? How can I recover committed transactions which were not archived at the time of crash, and I have a mirrored copy of log group which was current at the time of failure?

Appreciate an early response.

Hammad

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Re: How to recover unarchived data in case of media failure [message #540864 is a reply to message #540862]

Thu, 26 January 2012 06:41

Kamran Agayev
Messages: 145
Registered: February 2009
Location: Azerbaijan, Baku

Senior Member

If you have redo log files, you can backup with UNTIL CANCEL option and provide the name of the redo log file and make Oracle to apply all committed data from the redo log files

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Re: How to recover unarchived data in case of media failure [message #540866 is a reply to message #540862]

Thu, 26 January 2012 06:47

Michel Cadot
Messages: 68418
Registered: March 2007
Location: Nanterre, France, http://...

Senior Member
Account Moderator

If you have a backup and all archived logs and at least one member of redo logs then you can recover up to the last committed transactions.
No data lost.

Regards
Michel

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Re: How to recover unarchived data in case of media failure [message #540882 is a reply to message #540866]

Thu, 26 January 2012 08:24

hammad83
Messages: 46
Registered: June 2008
Location: Australia

Member

Thanks Guys,

Can you show me an example of how to do that using RMAN? After restoring the control files and data files, how to use saved copies of redo log files when applying archive logs in the recover stage?

Regards,
Hammad

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Re: How to recover unarchived data in case of media failure [message #540889 is a reply to message #540882]

Thu, 26 January 2012 08:53

Michel Cadot
Messages: 68418
Registered: March 2007
Location: Nanterre, France, http://...

Senior Member
Account Moderator

You use

restore database;
recover database;

Regards
Michel

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Re: How to recover unarchived data in case of media failure [message #540994 is a reply to message #540866]

Thu, 26 January 2012 23:36

hammad83
Messages: 46
Registered: June 2008
Location: Australia

Member

Worked like a magic. So simple Smile

Just to explain, after restoring the database, I copied the multiplexed redo log members of all groups and placed them into the missing redo log files locations, and renamed them to their old names (got them from v$logfile after mounting the database). Then I recovered the database. All the committed data was recovered from redo log files.

Thanks for your help.

Hammad

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