Re: Production problem: Fuzzy standby database
Date: Sat, 18 Jul 2009 17:47:23 +0400
Message-ID: <4A61D26B.2080808_at_rdtex.ru>
Hi,
I remember the discussion on fuzzy files recovery back in 2006.
Here is the URL
http://www.freelists.org/post/oracle-l/Restore-and-Recover-Fuzzy-datafiles
George, I think you are a little bit optimistic. Can not imagine any
structure in the
server code (X$-) or in database/flashback logs/block change tracing
files, were one
can find any label/mark showing that "all blocks in the files ..." in
fuzzy mode are pulled
out of it. The only mark i'm aware of - the end of thread redo.
Which means you've performed complete recovery, and there are no other
changes
left to apply. For example, you've copied current online redo "on the
fly" (with a possibility
of corruption), or made a shutdown before such a copy... And even
probaly then started up
the instance again... The important point is, that such a redo will have
a last redo block in
it. The next one would be either zero or will contain older (sequence
number?) redo
records.
Charles, you are in danger right now,
as you'll fail to activate your standby in usual way,
unless you have all the redo (including the current one) from the
production. Even in this
case you'll need to emulate "manual switchover", i.e. put current redo
in place,
recover database (including that current redo) and then recreate the
controlfile.
This is working scenario (at least in 9iR2 and 10g).
There is still some hope to avoid "flood of blood": switchover.
Indeed, it applyes ALL of the redo from production to the standby,
and, hopefully,
resets the fuzziness sign as well. Though I've not tested this scenario
personally.
You should experiment yourself.
--Andrey
Johnson, George wrote:
> If I can ask, how were the file backups taken? If you do simple copy or
> split mirror type backups and forget to "begin backup", it does this,
> block SCNs in the files cause the files to go "fuzzy", the answer is to
> keep on applying redo to until you pull all blocks in the files forward
> out of fuzzy mode.
-- http://www.freelists.org/webpage/oracle-lReceived on Sat Jul 18 2009 - 08:47:23 CDT