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Home -> Community -> Mailing Lists -> Oracle-L -> Re: Standby database v. advanced replication.
Your standby database will only be as accurate and up-to-date as the last
archived log you managed to send over to that site. Replication can keep you
absolutely up-to-date (via synchronous replication) but if you lose the
network you have to manually correct and resolve issues. OPS will not help
if you lose the disks.
As for going back from a standby site, I would turn the primary site into a standby site and "fail over" gracefully (i.e., do an alter system archive log all before a shutdown of the database). Then all your logs will be there and the primary can be restored to the minute. Some downtime when going back but....
Look through Metalink for papers on standby database by Lawrence To, he has one on "graceful switchover". There's also my paper on 24x7 on the www.oracle-users.com site at http://www.oracle-users.com/dba.htm
Rachel
>From: CHUCK_HAMILTON_at_qvc.com
>Reply-To: ORACLE-L_at_fatcity.com
>To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
>Subject: Standby database v. advanced replication.
>Date: Mon, 01 May 2000 09:15:12 -0800
>
>I have a requirement for a new 24x7 mission critical database. Occasional
>outages of < 5 minutes can be tolerated, but no longer. The fail-over
>options being considered are: (1) a standby database, and (2) advanced
>replication. OPS is not being considered because it does nothing to provide
>fast recovery from a media failure.
>
>I'm leaning towards a standby database because I've had bad experiences in
>the past with Oracle snapshots. Unless I'm mistaken, that's the same
>technology that advanced replication is based on. Oracle would always lose
>track of the fact that a fast refresh could be done and try to do a full
>refresh. Some of the tables in this database will contain up to 20m rows
>and 8g of data. Way too much to attempt a full refresh.
>
>Standby databases look like they're easier to implement and might be more
>reliable, but switching back I'm told is a problem.
>
>Has anyone out there made a similar comparison? What would your
>recommendation be? If you have any experiences to relate I'd like to hear
>about them.
>--
>Chuck Hamilton
>Oracle DBA
>QVC Inc.
>
>--
>Author:
> INET: CHUCK_HAMILTON_at_qvc.com
>
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