RE: Oracle Complete Recovery.
- From: "Goulet, Dick" <DGoulet@xxxxxxxx>
- To: <GJohnson@xxxxxxx>, <prabhu_adam@xxxxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
- Date: Mon, 26 Sep 2005 09:40:53 -0400
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@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Johnson, George
Sent: Monday, September 26, 2005 4:12 AM
To: 'prabhu_adam@xxxxxxxxxxx'; oracle-l@xxxxxxxxxxxxx
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@xxxxxxxxxxx]
Sent: 24 Sep 2005 17:24
To: oracle-l@xxxxxxxxxxxxx
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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