RE: Oracle Complete Recovery.

From: Goulet, Dick <DGoulet_at_vicr.com>
Date: Mon, 26 Sep 2005 09:40:53 -0400
Message-ID: <4001DEAF7DF9BD498B58B45051FBEA6502C8C455@25exch1.vicorpower.vicr.com>

Well, That's a very good point, at the end. A db is down, production or otherwise, panic is one's worst enemy. My rule of thumb is first go get a cup of coffee so as to allow the initial surge of Adrenalin to pass. Next comes the hard part, what broke? Is it the network layer, has happen to me several time that the listener process dies unexpectedly mainly from a SA who thinks processes shouldn't run that long. Second did the instance crash? It may be that one or two tablespaces crashed for one reason or another. Had a situation some time ago where a junior dba took the rollback segment (8.0) tablespace offline by accident. Which brings up the next question, what errors are people seeing? If one or more tablespaces, non system, are offline did something in the disk subsystem fail, like a controller card or drive? Once you know what broke, then it's what do I have to fix things? Like when was the last backup? Was it hot or cold? What was the purpose of the tablespace? If it was all indexes do I have the definition of those indexes as it may be easier to rebuild than recover. And in the end if you really do have to restore everything, first keep a copy of the current control file. Your going to need it as whatever is on the backup tape is old in comparison. And then finally there's either:

Alter database recover database;

Or just plain

Recover database;

But if all you lost was one file or tablespace that changes to something like:

Alter database recover tablespace/datafile <name>;

-----Original Message-----

From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Johnson, George Sent: Monday, September 26, 2005 4:12 AM To: 'prabhu_adam_at_hotmail.com'; oracle-l_at_freelists.org Subject: RE: Oracle Complete Recovery.

Just some thoughts on this, may be a little OT.

I always ask to have the interviewer clarify the exact situation as
they see it. I despise people who panic, "Oh DB has crashed and it's corrupted, quick get all the backups and all the logs and a new server and...". When you actually look at it, it crashed and one temporary tempfile
can't be found! In this instance ask them to clarify exactly what happened,
then assure him you will start with a good look through the alert logs and
trace files, if still possible, then work from there. Say you will order up
the tapes just in case, if they're offsite, then make a thorough investigation ASAP. This could be a simple test to see if you panic over what may be potentially nothing, like a missing tempfile! If they want to go
further, then you can say, "well after checking, if I found only one file, I
simply restore that, if required, then recover the file off the logs". Then
deeper if the corruption is worse. Getting tight down to a full restore/full
recovery only as a last resort, clarifying tech details only as required.

I got caught out once at an interview, years ago. "Reports coming in
about prod database down, what would you do?", I started banging on about
alert logs, trace files and recovery and the interviewer turned round and
said "Well actually, the help desk only got two calls from a 3,000 user base. A simple check on the PCs first, would have uncovered that their network cables had just been pulled by accident by a cleaner, vacuuming.".

Rgds

-----Original Message-----

From: Prabhu, K [mailto:prabhu_adam_at_hotmail.com] Sent: 24 Sep 2005 17:24
To: oracle-l_at_freelists.org
Subject: Oracle Complete Recovery.

All,

In an interview I'm asked this question that, how will you do complete recovery for a database which is running in archivelog mode. I answered as first I'll restore all the backups then I'll mount the database, then I'll start the recovery by using command alter database revocery.

But my interviewer was not statisfied with my answer and he asked me is there any other way you can recover the database without using alter database command.

As the interviewer said is there any other way we can do that ?

your help is deeply appreciated.

Thanks.
Prabhu

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http://www.freelists.org/webpage/oracle-l Received on Mon Sep 26 2005 - 08:43:00 CDT