October 15, 2007 at 6:19 pm
Hi ,
I am looking some information regarding scenario in SQL 2005 where project team wants 3 servers running as active and one extra server will work as passive or backup server so just wondering if that at all possible ? if yes any pointer will be great also just wondering if it is possible and two active nodes get down simulatenously then how it will be taken care of.
Thanks
October 16, 2007 at 4:54 am
Hi,
This topology is possible, where you have Active---Active---Passive SQL Server instances. The key will be your fail-over policy, which in worst case of both your Active servers failing, the Passive server would provide services for both previously Active instances, but introducing a single-point-of-failure. All your servers would need to join the same cluster group and you will need to consider your storage presentation strategy, as you have only 26 letters to work with unless you use mount points. In addition, your memory allocation needs to be considered, as in worst case, you would have two instances running on a single server.
Hope this helps,
Phillip Cox
October 16, 2007 at 6:27 am
I've found that this idea isn't generally well recieved, to me it sounds good as a limit to having resource sat around doing nothing - your failover ( passive ) node would have to have the combined resource of the other three nodes, for worst case scenario, unless you are willing to accept the risk of degraded performance whilst the failed node is brought back/replaced.
[font="Comic Sans MS"]The GrumpyOldDBA[/font]
www.grumpyolddba.co.uk
http://sqlblogcasts.com/blogs/grumpyolddba/
October 16, 2007 at 8:14 am
..which ultimately comes down to a business decision. I've seen more implementations using a 3/2 scenario, but it's going to be a factor of how much performance they're willing to give up. It actually might be cheaper to have more, smaller machines that can handle 2 instances each than one that can handle all of them.
Bring up the concerns, but let the decision lie with the decision-maker.
Finally - you could configure one of the ACTIVE's to be a failover node for one of the other actives (if one of the actives happens to be somewhat less busy than the others).
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Your lack of planning does not constitute an emergency on my part...unless you're my manager...or a director and above...or a really loud-spoken end-user..All right - what was my emergency again?
October 16, 2007 at 8:23 am
Thanks All for your comments ,much appreciated , so there is any supportive document to support this kind of scenario ?
October 16, 2007 at 9:12 pm
We use the PolyServe Matrix Server Database Utility for SQL Server to run 2 distinct 5+1 'clusters'.
http://www.polyserve.com/sql_server_consolidation.php
They push it as useful for consolidation, we went with it to get rid of MS clustering. We also freed up several database servers by switching from many active-passive clusters to the two six-node clusters for production databases. We're using the extra servers to set up either an 8-node cluster or two 4-node clusters to hold all of the database mirroring instances.
If nothing else, you need to experience their tech support. No other vendor I've ever dealt with has come close to the service we get from them - at any price.
-Eddie
Eddie Wuerch
MCM: SQL
October 17, 2007 at 1:34 pm
sqlquery (10/16/2007)
Thanks All for your comments ,much appreciated , so there is any supportive document to support this kind of scenario ?
There are general documents on clustering and SQL Server clustering but I don't think there is one for 3 active instances on a 4 node cluster because that's just a particular setup in a clustering configuration.
K. Brian Kelley
@kbriankelley
October 17, 2007 at 2:42 pm
that's interesting Eddie, thanks for the recommendations I'll file it away for such time as I might need it.
[font="Comic Sans MS"]The GrumpyOldDBA[/font]
www.grumpyolddba.co.uk
http://sqlblogcasts.com/blogs/grumpyolddba/
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