recovery of corrupted UNDO tablespace

[sivakumarocp]

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.

[Tim...]

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...

[sivakumarocp]

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

[Tim...]

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...