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restarting a rman restore from Tape backup [message #325644] Sat, 07 June 2008 01:47 Go to next message
hrishy
Messages: 25
Registered: August 2005
Junior Member
Hi

One of my friend had a very slow RMAN restore going on .
There was no wait events in v$session_wait the backup of 300Gb took 1.5 hours but the restore has already taken 18 hours and hasn't still completed.

I don't have much idea about media managers and all but out of curiosity i am asking if you kill a restore job from the Unix prompt and restart it will RMAN restart from the point it failed or will it restart from the beginning.

I vaguely remember that when you are cloning a database from standby if the clone fails in between and you restart the restore i think it will start from the point of failure and not from the beginning is this correct.

regards
Hrishy
Re: restarting a rman restore from Tape backup [message #325704 is a reply to message #325644] Sat, 07 June 2008 12:41 Go to previous messageGo to next message
ebrian
Messages: 2794
Registered: April 2006
Senior Member
Unfortunately, RMAN doesn't have a restartable restore feature, however you could determine which files have already been restored and then just issue RESTORE DATAFILE n1, n2, n3 ... nm for the remaining files.

[Updated on: Sat, 07 June 2008 12:41]

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Re: restarting a rman restore from Tape backup [message #325723 is a reply to message #325704] Sun, 08 June 2008 02:46 Go to previous messageGo to next message
hrishy
Messages: 25
Registered: August 2005
Junior Member
Hi Ebrian

Thanks for responding.

But what is meant by this in the documentation
http://www.stanford.edu/dept/itss/docs/oracle/10g/server.101/b10734/rcmconc2.htm

Quote:

By default, RMAN does not perform a restore if the file to be restored is in the correct place and its header contains the expected information.

RMAN only restores a file if the header check does not succeed, although you can use the FORCE option of the RESTORE command to override this behavior and restore the requested files unconditionally.


ote:
Restore optimization only checks the datafile header and does not the scan the datafile body for corrupted blocks.

Restore optimization is particularly useful in cases where a restore only partially completes. For example, assume that a full database restore encounters a power failure after all except one of the datafiles has been restored. If you start the same restore again, then RMAN only restores the single datafile that was not restored during the previous attempt.

[Updated on: Sun, 08 June 2008 04:58] by Moderator

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Re: restarting a rman restore from Tape backup [message #325772 is a reply to message #325723] Sun, 08 June 2008 10:45 Go to previous messageGo to next message
ebrian
Messages: 2794
Registered: April 2006
Senior Member
For duplication, you may want to review Note: 360962.1 which addresses manually completing a failed duplication with RMAN. It specifically mentions using a "normal" RMAN restore command to manually restore files that have not been restored already. This is what my previous response was referring to.

HTH
Re: restarting a rman restore from Tape backup [message #325782 is a reply to message #325772] Sun, 08 June 2008 12:28 Go to previous messageGo to next message
hrishy
Messages: 25
Registered: August 2005
Junior Member
Hi

Ebrian thanks again i am not trying to duplicate here i am restoring the backup from a tape drive.So i am just wundering what would happen if i kill a rman session at the unix level and if restart it would RMAN pick up from the place where it left off during the next restore ?

or it would start a afresh

regards
Hrishy
Re: restarting a rman restore from Tape backup [message #325783 is a reply to message #325782] Sun, 08 June 2008 12:34 Go to previous messageGo to next message
ebrian
Messages: 2794
Registered: April 2006
Senior Member
Sorry, I saw mention of cloning.

With normal restore operations, RMAN will perform as indicated in the link you provided above and should skip any datafile already restored. Are you seeing otherwise?
Re: restarting a rman restore from Tape backup [message #325820 is a reply to message #325783] Mon, 09 June 2008 01:26 Go to previous messageGo to next message
hrishy
Messages: 25
Registered: August 2005
Junior Member
Hi Ebrian

Thanks.
I havent tried it till now i wanted to confirm before giving it a try.Would ask my friend to kill the restore and restart it again thanks for the advise i appreciate very much.

Eeven during cloning i think it should be restartable isnt it ?

regards
Hrishy
Re: restarting a rman restore from Tape backup [message #325995 is a reply to message #325820] Mon, 09 June 2008 20:37 Go to previous messageGo to next message
ebrian
Messages: 2794
Registered: April 2006
Senior Member
To be honest, I never had the need to restart a canceled duplication, so I tested it myself on Linux 10.2.0.1 and found that RMAN is able to skip files that were already fully restored during a canceled duplication. Note:360962.1 seems to pertain to 10.2, so I'm not really sure why it recommends restoring the datafiles individually? Maybe it depends on the reason for the failed duplication, however the note doesn't clearly explain that.

That's what I get for relying on Metalink's notes without testing. Thanks for making me test that Note's assertion.
Re: restarting a rman restore from Tape backup [message #326061 is a reply to message #325644] Tue, 10 June 2008 01:45 Go to previous message
hrishy
Messages: 25
Registered: August 2005
Junior Member
Hi Ebrian

A million thanks Smile.

I appreciate very much.

regards
Hrishy
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