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MS SQL Server 2008 R2 Multi Instance Cluster


I'm planning to setup Multi-instance (Active/Active) Cluster using MS SQL Server 2008 R2 on Windows 2008 R2. The reason for this setup is to achieve better utilization of the hardware (since both the servers will be used to support database transactions).  

My intention is two have two instances in the cluster with one running on node 1 and other running on node 2 and they will failover to the other nodes in case of any issues. I'm trying to get some direction to achieve this, and I'd appreciate if somebody can point me to the right direction and hopefully provide some link if they've implemented the same setup.

5 Solutions
In effect you will have two clusters an application cluster per instance.
Make sure to allocate resources such that both can run on the same node
i.e. if you have a 16GB RAM, make sure to allocate the maximum of 7GB to each SQL instance.

Ryan McCauleyData and Analytics ManagerCommented:
If you're looking for an actual step-by-step on the cluster configuration and sql cluster installation itself, I've always loved this walk-through:


In your case, you'll want to set each instance to have a primary node so that they stay on different nodes (when both nodes are available), and then they'll fail over to the "secondary" node when the instance's primary node becomes unavailable.

We use an active/active configuration like you're describing, but have about 15 SQL instances on our cluster, with half set to have one node as the primary and half set to have the other node - that way they balance themselves when both nodes are available, but will fail over to the secondary node when one goes down unexpectedly.

this link shows windows cluster install and page 3 is where sql install starts.

After one node is primary, you can go to the secondary node and do installs the other way round.

please check on the requirement for all ip addresses related to a cluster need to be in the same subnet. Installs can fail if they are not. However, I am not sure if this is now different for win2008(r2)/sql2008(r2)
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You can install on the same node and shift them as you see fit.  Designating which node will have which instance active is part of the configuration and does not require the installation to occur on that node.

Getting better utilisation out of an existing A/P cluster is a good thing, but dont overlook the reason why a cluster was created in the first place...
Ryan McCauleyData and Analytics ManagerCommented:
Steve makes a good point - when you have active instances on both nodes in your cluster, there are a few things to remember:

Don't use more memory for all instances combined than you have in any one node - that way, you don't run into sudden memory pressure and instability when all instances fail over to a single node.
In an active/passive configuration, you only need to license the SQL Server on one side, and the passive node doesn't require a SQL Server license. However, if you're going to keep instances active on both nodes, you'll need to license both as well - could get expensive.
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