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RE: Standby Instance questions and HA

From: <Simon.Anderson_at_scisys.co.uk>
Date: Fri, 18 Jan 2002 11:18:13 -0800
Message-ID: <F001.003F3FEA.20020118102051@fatcity.com>

I've seen a similar idea running on Silicon Graphics kit :

     2 servers;
     heartbeat check between them;
     Drives mount on the other box when the 'live' system fails

It was nice when it worked...Testing the failover caused barely a ripple, although it did disconnect any open sessions. Alas, it rarely worked that well when there was an actual problem.

As with the Sun solution, no extra charge from Oracle, but added costs from SG.

Still, who in their right mind would choose to run a production database on discontinued SGI machines?

Simon Anderson

Please respond to ORACLE-L_at_fatcity.com

To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com> cc: (bcc: Simon Anderson/SSplc)

We have this in place on Sun as well. It is similar to a cluster in that it has a separate box (Ultra 2) monitoring a heartbeat between both database servers. You will have a significant impact during failover. All drives common to both boxes will be unmounted on the primary and remounted on the secondary (which then becomes the primary). Since a "fsck" is run for each file system it can take upwards of 30 minutes for the failover. The database is shut down and brought back up so all connections are severed which means an interruption of service.

If I wanted H/A on Sun I would move to 9i and implement a RAC. No application changes are necessary with this new version of OPS.

Good luck.

--Michael

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

Sent: Thursday, January 17, 2002 11:03 AM To: Multiple recipients of list ORACLE-L

Jim:
Sorry, you're not gonna like this answer. HA is a Sun product, not an Oracle product. Under Sun's High Availability, you can configure several modules like Sybase and Oracle. (The Oracle product is Sun Cluster HA-DBMS for Oracle.) It does require what I believe Sun calls a cluster but (IMHO) is a bastardization of the term. It truly is failover, not cluster.

We've had lots of problems with it. It's caused us lots of grief, and only in a few instances gained us anything. It is NOT OPS, as the database does not run in parallel, but only on 1 box at a time. (Everything is double cabled, and so the drives are re-mounted on the 2nd box if a failover occurs.) Your users still get disconnected. You'd probably lose less data than with a standby (since you pick up with the same drives mounted on the other box), but it depends on how you have the standby implemented.

There's no additional cost from Oracle to run this crap, but you'll be paying Sun great sums of money. The Sun web site has more info on HA.

Let me know if you need more info.
Good luck!

Barb

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