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kpsenthilkumar86 avatar image
kpsenthilkumar86 asked

SQL Server Always on

Hi All, I am a DBA. In our organization we are using SQL Server 2012. So far, the High Availability concepts that I have worked are Mirroring & Log shipping. Now, we are planning to implement "Always on" in our organisation, which is new to all of us. My doubt is, when windows server failover clustering is enabled on the secondary server, can the same server be used as secondary IIS/mail/file server. Moreover, We need to test "Always on" in our current secondary server(which is now used for mirroring) and testing shouldn't disturb the current setup. Is that possible? Please advise us in this regard. Thanks in advance. K.P.Senthil Kumar
sql server 2012always-on
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Hi All, One more clarification please. If I am having two instances on secondary server, can any one of the instance used as the secondary and remaining one instance be used for some other purpose(may be as the testing server/UAT server). The reason for asking this is, I am not clear whether the AO works at instance level or at windows server. Thanks & Regards, K.P.Senthil Kumar
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Always on Availability Groups use Windows Failover Clustering Service, that is a windows level service. It also uses mirroring technique to synchronize databases between SQL instances, that is a SQL instance level feature. So the answer is that it works at both SQL and OS levels. And don't forget, do not do it for the love of god/gods (all religions).
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raadee avatar image
raadee answered
Not sure if you are talking about Always on as in Failover Cluster or Availability groups since both use failover clustering. Either way you are way off when you are thinking about sharing an "Always On" server with other services such as IIS/MAIL. You should not test this in your production environment either, I am not sure how you can test any always on feature on one server? Separate test from production. Separate SQL and all other features. And get other server for Always on. If they wont gice you new servers, do not go always on. It will be always off in the end..
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Well you need to install Failover Cluster service. Then you probably need to patch the server to use Availability Groups since there are a number of patches that affect it. Just do not do it, it is plain wrong.
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I'm 100% with @raadee on this. You need to test this somewhere other than your production servers. You're negligent if you do anything else.
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Hi raadee, what I mentioned is just for clarification. The secondary server is dedicated only to SQL. But, what I need to know is can a mirrored server is used for testing "Always on" without the mirroring get affected.
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Grant Fritchey avatar image
Grant Fritchey answered
Can you run an availability group and a mirroring set up on the same set of servers? Yes. Can you install an availability group onto an existing set of servers running mirroring without affecting mirroring? Probably not. At the very least you're likely to have to restart the server after getting the Clustering service started. The reboot alone will cause at least a temporary disruption of your mirroring set up.
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