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recovery of corrupted UNDO tablespace

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sivakumarocp
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recovery of corrupted UNDO tablespace

Postby sivakumarocp » Mon Oct 29, 2012 4:00 am

Hi Tim,

I am not clear with UNDO tablespace recovery.
consider below two scenario.

Scenario 1:

If we lost any of undo datafile how can we recover? can we just use RMAN restore and recover of that datafile alone?

Scenario 2:

If our undo datafile got corrupted then how could we recover?

When I googled it, it says like inorder to recover corrupted undo datafile we need to set the UNDO_MANAGEMENT paramter to MANUAL and need to create new undo tablespace then make it online followed by need to change UNDO_MANAGEMENT parameter to AUTO.

but why dont we use BLOCKREPAIR or just mran restore or recover command in scenario 2.


Kindly explain in detail.
Regards
Sivakumar.A
www.sivakumardba.com

Tim...
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Re: recovery of corrupted UNDO tablespace

Postby Tim... » Mon Oct 29, 2012 9:16 am

Hi.

The undo tablespace is a normal tablespace, so it can be recovered by RMAN in the normal manner. Like all tablespaces, undo is protected by redo logs, so it is recoverable in the same way.

Cheers

Tim...
Tim...
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sivakumarocp
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Posts: 260
Joined: Sat Jun 27, 2009 3:53 am
Location: India

Re: recovery of corrupted UNDO tablespace

Postby sivakumarocp » Mon Oct 29, 2012 2:55 pm

Still I am not clear!
could you explain in detail. when we need to use RMAN and when we should go for changing UNDO_MANAGEMENT parameter to AUTO
Regards
Sivakumar.A
www.sivakumardba.com

Tim...
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Posts: 18437
Joined: Mon Nov 01, 2004 5:56 pm
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Re: recovery of corrupted UNDO tablespace

Postby Tim... » Mon Oct 29, 2012 4:27 pm

Hi.

You don't need to do anything different than a regular tablespace recovery. I don't do any switching of undo management etc. I just do a tablespace recovery.

The undo tablespace is just like any other tablespace. It contains segments that are protected using redo logs, just like table segments are.

Why don't you try doing a recover on a test system, just to prove it to yourself?

Cheers

Tim...
Tim...
Oracle ACE Director
Oracle ACE of the Year 2006 - Oracle Magazine Editors Choice Awards
OakTable Member
OCP DBA 7.3, 8, 8i, 9i, 10g, 11g
OCP Advanced PL/SQL Developer
Oracle Database: SQL Certified Expert
My website: http://www.oracle-base.com
My blog: http://www.oracle-base.com/blog


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