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I have created an environment where 1 SAN is connected with 2 Nodes (part of SQL Server 2012 Failover Cluster) of SQL Server. Windows Server 2008 R2 is used, and single DB is stored in SAN.

We have achieved High Availability with 2 nodes and since there is a switch used to connect to SAN, it ensures that active node (which is one at a time) is connected to SAN, but other one is disconnected.

I wanted to know if I want to "scale" this architecture, how can we ensure that multiple "Active Nodes" are connected to SAN, is there a way somehow? This will help me add new nodes to SQL Server Cluster and try out various combinations like 2 active 1 passive etc.

I am from a developer background and not a server admin, please excuse if something is naive. Please help me understand. References to read are welcome.

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First of all you need to be running SQL Server 2012 Enterprise edition.

Second, you need to create an AlwaysOn Availability Group(AAG).
You can have up to 4 replicas (5 total db servers) in an AAG.

You can change the AAG mode to synchronous or asynchronous. You also have the option of Read-Only replicas for things like Business Intelligence, Analysis, and Reporting.

This is one of the High-Availability configurations available in SQL Server 2012. You can combine a Failover Cluster with AAG.

  • I don't want to keep replicas, basically DB will have one "storage" copy in SAN. I don't want replication to come in pic. Our SAN will scale IO operations from multiple SQL Server Instances. I just want to connect Multiple SQL instance to provide scalability, which currently is not happening due to Switch. AAG's create replicas as far as I know. Please excuse if I got you wrong. – Ashish Jain Feb 7 '14 at 8:49
  • I see what you mean. Wouldn't using a SAN for this be redundant, since the SAN priorities IO over two paths? AAG does create replicas. – Vasili Syrakis Feb 7 '14 at 9:01
  • Two paths? Basically it should point to "same file system" single copy of DB, its kind of concurrent access to same Filegroup via multiple instances of SQL Server. I think it would be difficult to achieve in SQL Server. – Ashish Jain Feb 7 '14 at 9:08
  • serverfault.com/questions/450478/… Shows my approach is wrong. Thanks for help. – Ashish Jain Feb 7 '14 at 9:15

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