RE: Corruption in SYSTEM Tablespace

On Mon, 29 Oct 2001, Gogala, Mladen wrote:

> Restore the last hot backup and do the database recovery.

Well that seems a little extreme.

Why not find out which objects contain corruptions first, and if the corrupted areas actually contain data? Why go through a restore/recover without having all the information?

Use dba_extents to find out which objects the corrupted blocks belong to. If they are indexes, just rebuild them! If they are heap-organized segments (tables/clusters), then find out if there are actually rows in the affected area, by selecting a range of rowids using dbms_rowid.

Only if you find that the corruptions have damaged actual data do you have to recover. Even in that case, as long as you are using archivelog mode, you can resotre and recover just the datafile(s) containing the corruptions, and perform complete recovery of that file(s) with the database in mount mode.

Finally, make sure you find out how the corruption happened. The O/S shouldn't just corrupt your database. The SAs should identify the root cause and rectify it.

--
Jeremiah Wilton
http://www.speakeasy.net/~jwilton



> > -----Original Message-----

> > From: Rajesh Dayal [mailto:Rajesh_at_ohitelecom.com]

> >

> > Fortunately this is there only in my TEST database. But I am

> > wondering, how to resolve if this happens in Production Database.

> >     I can't export Full database with zero errors. Although I can

> > export most of the schemas individually. Dbverify shows some 3 blocks

> > to be corrupted, that's too only in SYSTEM TS.

> > Any ideas would be appreciated.


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Author: Jeremiah Wilton
  INET: jwilton_at_speakeasy.net

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