RE: NetApp flier - based snapshots and db backups
- From: "Bobak, Mark" <Mark.Bobak@xxxxxxxxxxxxxxx>
- To: <kevin.closson@xxxxxx>, <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 20 Jul 2007 15:37:01 -0400
Just to add on to what Kevin said....I used to have conversations w/ my
storage guy ,and get totally confused, cause he was speaking EMC
language and I was speaking Oracle language. When we finally got
someone from EMC on the phone that understood both sides, the
terminology she used, which finally allowed me to see the light, was
that one method is "recoverable" the other is "restartable".
Recoverable refers to a conventional backup. You put the tablespaces
into backup mode, split the mirrors, and exit backup mode. The
"snapshot" is not recoverable, it's restartable. It's basically a copy
of everything, datafiles, controlfiles, and redo logs, all
self-consistent. Note that the restartable snapshot MUST include the
redo logs, and a recoverable backup copy NEVER should.
Now, granted, up to now, this was about NetApp, and I'm talking EMC,
but, conceptually, the ideas are the same. The key concept to get is
that a snapshot, taken while the database is up and running, and
tablespaces are not in backup mode, is restartable, not recoverable.
The confusion I referred to in previous conversations w/ my storage
admin all centered around the fact that he didn't make (didn't know to
make) a distinction between restartable and recoverable! He'd say "EMC
says it will work, they have customers that do it all the time!" And
I'd tell him "If the tablespaces aren't in backup mode, I can't recover
it!!"
-Mark
--
Mark J. Bobak
Senior Database Administrator, System & Product Technologies
ProQuest
789 E. Eisenhower, Parkway, P.O. Box 1346
Ann Arbor MI 48106-1346
734.997.4059 or 800.521.0600 x 4059
mark.bobak@xxxxxxxxxxxxxxx <mailto:mark.bobak@xxxxxxxxxxxxxxx>
www.proquest.com <http://www.proquest.com>
www.csa.com <http://www.csa.com>
ProQuest...Start here.
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Closson, Kevin A
Sent: Friday, July 20, 2007 2:26 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: RE: NetApp flier - based snapshots and db backups
be aware that a database in a filesystem snaphot looks EXACTLY like it
would if you pulled the electricity from the database server when Oracle
was up and running. You cannot roll forward from such an image. NetApp
documents all this quite well...just be aware that there is no magic ...
________________________________
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Vasu Balla
Sent: Friday, July 20, 2007 10:24 AM
To: vbarac@xxxxxxxxxxxx; oracle-l@xxxxxxxxxxxxx
Subject: RE: NetApp flier - based snapshots and db backups
Oracle OnDemand, which hosts more than 1000 databases on netapp filers,
uses this snapshot functionality for backup. you are not alone :)
vasu
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