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kenymaciel avatar image
kenymaciel asked

SQL Server 2012 - Multiple named Instances with Always On

Hi, Can anyone help me? I have two named SQL 2012 standalone Instances on each server. I would like to know what the best way to set up Always On . INST1(Principal) on SERVER1 --> Replica on INST2 INST2(Principal) on SERVER2 --> Replica on INST1 OR INST1(Principal) on SERVER1 --> Replica on INST2 INST2(Principal) on SERVER1 --> Replica on INST2 Thank you very much for your time and I really appreciate it!!! +Keny
sql server 2012always-onavailability-groups
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are all of the replicas going to be synchronous or will some be asynchronous?
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Hi KenJ, The replicas will be asynchronous?
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KenJ answered
If your severs see very much load, I would lean toward running the primary roles on separate servers. You might get some resource utilization benefit from splitting the primary roles out since CPU and I/O will tend to be more evenly balanced across the servers. If your servers are lightly utilized, then this isn't a critical decision. You can always set it up one way the, if you need to, change it later by synchronizing the replicas and failing over.
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Excellent answer, Ken. I only added my own answer to point out the potential licensing (and therefore cost) differences.
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Tom Staab answered
I'm a big fan of splitting the primaries because it is essentially a form of load balancing. If you're paying for the individual server licenses anyway, you might as well use them. That said, if you only have 1 license of SQL Server, you might be able to have a free passive instance running on another server. In that case, and if the performance will be acceptable, you might be better off running all primaries on a single server. Microsoft says the following in the [SQL Server 2016 Licensing Guide][1]. For each server licensed with SQL Server 2016 and covered by active SA, customers can run up to the same number of passive failover instances in a separate, OSE to support failover events. A passive SQL Server instance is one that is not serving SQL Server data to clients or running active SQL Server workloads. The passive failover instances can run on a separate server. These may only be used to synchronize with the primary server and otherwise maintain the passive database instance in a warm standby state in order to minimize downtime due to hardware or software failure. I did some research and found the corresponding document for SQL Server 2012: [ http://download.microsoft.com/download/6/4/A/64A1EC8F-F575-41E1-9D34-821FA9F98F8E/SQL_Server_2012_Licensing_Reference_Guide.pdf][2] It looks like the 2012 license doesn't always require Software Assurance, but if you have licensing questions, I recommend you contact Microsoft directly. [1]: http://download.microsoft.com/download/9/C/6/9C6EB70A-8D52-48F4-9F04-08970411B7A3/SQL_Server_2016_Licensing_Guide_EN_US.pdf [2]: http://download.microsoft.com/download/6/4/A/64A1EC8F-F575-41E1-9D34-821FA9F98F8E/SQL_Server_2012_Licensing_Reference_Guide.pdf
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That's a good point on the licensing. If the asynchronous replicas are for DR, keeping the primaries together could make perfect sense.
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