Re: re-build physical standby in DG setup
- From: "joel garry" <joel-garry@xxxxxxxx>
- Date: 20 Jul 2006 12:01:32 -0700
EdStevens wrote:
Subject: re-build physical standby in DG setup
Platform: Oracle 10.2.0.1.0 on Solaris 10
DataGuard configuration with a physical standby database. Through an
unfortunate set of circumstances, a couple of archivelog files didn't
get shipped, then got deleted from the primary site. (yes, I'm the
guilty party) (And when I asked the server admin guys if they could
restore the archivelog files from a server level backup, they
discovered that *their* backup procedure had been failing!)
This is why I'm paranoid about backing up archive logs multiple times,
and not deleting them for at least 3 days (ie, log shipping breaks
Friday night of a 3 day weekend, Tuesday morning I can still suck from
several online backups).
As I understand, that leaves the standby unable to complete it's
recovery, so I need to rebuild it almost from scratch. I say
'almost' because, as I read the chapter on creating a physical
standby in the DataGuard Concepts and Admin manual, it appears that
several of the steps that were done on the initial setup are still good
and can be bypassed for this exercise. Here's how I see this shaking
out. Please tell me if I'm getting ready to dig the hole even
deeper, if there's an easier way out, or if I'm on the right track
but need to consider a few more items.
Following the setup steps in the doc, I should be able to bypass
everything dealing with creating the primary database. It was/is up,
and the only thing I've done is stop archive shipping, to prevent
filling up the recovery area target on the standby.
On the standby, comments on each step:
3.2.1 - Create Backup Copy of the Primary Database datafiles.
(yes, use rman to backup datafiles. This will need to be a hot backup.
Just the files listed in DBA_DATA_FILES? Include the SYSTEM
tablespace?)
Yes, everything. I'm jealous that 10 doesn't require everything to be
in the exact same place :-)
3.2.2 - Create Control file for standby
(it says "if the backup procedure required a shutdown of the primary
....". I would think I could skip this and go with the existing
control file of the standby, but am unsure of its record of archive
sequences)
Only if you have an unbroken log sequence. You don't. You need a new
controlfile for standby. I think (there may be something in 10g I
don't know about, but I don't see any relevant new features). But it's
easy enough
http://download-west.oracle.com/docs/cd/B19306_01/server.102/b14239/rcmbackp.htm#sthref2283
3.2.3 - Prepare initialization parameter file for the standby
(again, I should be able to go with the spfile that is already in
place)
3.2.4 - copy files from the primary to the standby
(yes to the backup data files, but no to the control file and parm
file)
3.2.5 - Set up the environment to support the standby database
(already there)
OK, but for standby controlfile.
3.2.6 - start the physical standby
-- startup mount
-- alter database recover managed standby database disconnect from
session;
(yes)
(extra item: restart log shipping on the primary)
3.2.7 - verify physical standby is performing properly
(run log switches, examine results --- yes)
If this is essentially correct, I would also think I can simply delete
a bunch of now obsolete archivelogs, followed by rman crosscheck and
delete obsolete on the primary. What of archivelog cleanup on the
standby, where the db is not open?
Once they are applied, no problem. I use the same paranoid deletion on
the standby as the primary, but that is generally overkill that I
rationalize as something I won't have to change if it becomes primary.
Although, I've seen flaky situations where I've needed to redo the
restore and have been glad those arcs hadn't been deleted yet. I can't
imagine a scenario where that would make sense beyond a few days after
the restore, though. (I had one special situation that took a week to
catch up).
Anything I'm overlooking or failed to consider?
jg
--
@home.com is bogus.
http://www.scaryplace.com/ScaryPlace.html
.
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