Destroying a cluster

I'm going to need to move a Windows 2008 R2 Cluster to a new domain.  The Cluster has 3 SQL Server 2008 R2 FCIs. I understand that I'll need to tear down and rebuild the cluster. The cluster will have to use  the same physical servers.

When I've removed FCIs in the past we removed the individual nodes.  Looking at Alan Hirt's 2008 clusering book apparently you can instead destroy the cluster rather than removing the individual nodes and then destroying the cluster.  Are there any downsides to simply destroying the cluster rather than removing the nodes?  Is there a preferred approach?

thanks

September 2nd, 2015 12:20pm

The real question is how you want to do the transition... If you destroy the entire cluster you will at the same time kill the SQL instance as well. The idea of removing nodes is that you remove one node first, already build up the new cluster with that hardware (while the old cluster is still running on the other nodes), then transition the databases to the new cluster and only then tear down the remainder of the old cluster to reuse the other servers.

So the difference more or less is that you have less work but more downtime. ;-)

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September 2nd, 2015 12:38pm

What's your RTO? There's a reason that those SQL Server instances are FCIs - it means they require high availability. If you destryo your cluster, the FCIs will be offline until you are ready to transition.

Also, what is your upgrade/migration plan? If you will be spending this much effort to move to a new domain, it might be a worthwhile investment to include upgrading to Windows Server 2012 R2 and SQL Server 2014

September 2nd, 2015 4:16pm

Unfortunately they won't let us upgrade as part of this process.  The client indicated they'd allow 8 hours of downtime. With 3 FCIs I don't know that there's enough time to completely rebuild and migrate in that time frame.

I'm thinking of the approach suggested by Prince above.  It would allow us to leave the old cluster operating on a single node while we build a single node cluster in the new domain. We can then migrate to the new single node cluster, and  then rebuild the second node.  They want the original virtual names so there would be renaming as part of the process.  A rough plan is below. 

Any thoughts?

  

When

  
  

Task

  
  

Notes

  

Pre-migration

Remove old FCIs from node2

Pre-migration

Evict node2 from old cluster

Pre-migration

Unmount disk from node2

Pre-migration

Move node2 to domain2

Pre-migration

Mount new disk to node2

Pre-migration

Build new WSFC on node2

Pre-migration

Install New FCIs on node2

Use different SQL virtual names   but same instance names

Pre-migration

Migrate System Database objects  

Migration Phase 1

   Stop applications

Migration Phase 1

Backup databases on old instances

Migration Phase 1

Migrate Databases to new instances  

Migration Phase 1

Rename old FCIs

Rename to temporary name

Migration Phase 1

Rename new FCIs

Rename to the original FCI virtual   names

Initial   migration complete.  At this point there   is a new single node cluster  using the   old cluster name in the new domain

Migration Phase 2

Remove FCIs from node1

Migration Phase 2

Destroy old cluster

Migration Phase 2

Unmount old disk

Migration Phase 2

Move node2 to domain2

Migration Phase 2

Make node 2 potential disk owner

Migration Phase 2

Add node 2 to cluster

Migration Phase 2

Add FCIs on node2

Migration   complete.  At this point there is two  node cluster  using the old cluster name in the new domain

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September 2nd, 2015 10:23pm

Thanks for the reply - very helpful.
September 2nd, 2015 10:26pm

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