'maxcorrupt' and corruption detection by RMAN

From: Ravi <nospam_at_newsranger.com>
Date: Fri, 19 Oct 2001 17:52:55 GMT
Message-ID: <XLZz7.35661$ev2.43420@www.newsranger.com>

Environment details:

RDBMS Version: 8.0.6.1
Operating System and Version: Solaris 5.8 Product (i.e. SQL*Loader, Import, etc.): Recovery Manager (RMAN) Product Version: 8.1.5

Problem:
One of our production database's datafile was corrupted and dbverify showed this error.

DBVERIFY - Verification starting : FILE = /blah/unix/cen/oracle/ datafiles/vc1merk/VC1MERK.1.G1MP01.dbf
kdbchk: xaction header lock count mismatch trans=1 ilk=1 nlo=2
Page 22966 failed with check code 8

DBVERIFY - Verification complete

Solution:
We exported the data, dropped the tablespace, recreated the tablespace and imported the data.

Now to the most important part.
Question/s:

Why did not R-man backups detect this corruption? I am 90% sure noone changed the 'maxcorrupt' parameter so it should be set to zero. Are there certain corruptions that RMAN doesn't detect?
How do I check my present maxcorrupt value to be 100% sure if I had to issue the 'set maxcorrupt to 0' command in RMAN?
Is the 'set maxcorrupt to 0' need to be issued everytime I do R-man backup? Or once its set, its set forever, until we change it again by another 'set maxcorrupt to n' command?

Thanks a lot in advance for your responses. Received on Fri Oct 19 2001 - 12:52:55 CDT