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DBA in the making
Aged Yak Warrior
638 Posts |
 Posted - 2011-09-20 : 07:23:40
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| When mirroring 2 database on 2 servers in separate datacentres, how much of an effect will there be on performance if there is no witness server? As I understand it, the witness server is there to provide high availability, not performance. But one of my colleagues is insisting that without a witness server, we will experience a huge hit in performance. Many thanx in advance.------------------------------------------------------------------------------------Any and all code contained within this post comes with a 100% money back guarantee. |
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spirit1
Cybernetic Yak Master
11752 Posts |
Posted - 2011-09-20 : 09:51:00
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| if you don't have a witness you can't have auto failover. that's about it.you can have sync or async mirroring in any case so i don't see what perf hit is your coworker talking about.if you have a sync mirroring then all your transactions will wait until they've been mirrored. if your netwerok has high latency then you'll experience wait times.but to be honest if you don't have a witness and a need for auto failover then you don't really need sync mirroring. IMO.___________________________________________________________________________Causing trouble since 1980Blog: http://weblogs.sqlteam.com/mladenpSpeed up SSMS development: www.ssmstoolspack.com <- version 1.9 out!SQL Server MVP |
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DBA in the making
Aged Yak Warrior
638 Posts |
Posted - 2011-09-23 : 12:04:44
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| Well, the debate started when he wanted to use log shipping to update our DR server, and I wanted to use mirroring. He said that we'd need a witness server, and I said that even without a witness, mirroring was still better then log shipping, because updates occur in real time. That's when he hit me with the performance issues bit. Thanx for your reply. That's pretty much what I thought.------------------------------------------------------------------------------------Any and all code contained within this post comes with a 100% money back guarantee. |
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Kristen
Test
22859 Posts |
Posted - 2011-09-24 : 07:46:07
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What's the network performance like to your DR server? I would be worried about performance for sync mirroring unless network performance is "stellar"  - assuming that the DR server is in another part of the world, rather than sitting next to the main server. |
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DBA in the making
Aged Yak Warrior
638 Posts |
Posted - 2011-09-26 : 06:50:23
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| Network Performance is pretty good. We have a high speed fibre link between both data centres.------------------------------------------------------------------------------------Any and all code contained within this post comes with a 100% money back guarantee. |
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Database Mirroring - Witness Server