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MikeHinds asked

Best Practices with VMs in Clusters

Our organization has about 130 SQL instances. Most are VMs (on Hyper-V). The more mission-critical VM SQL instances are failover-clustered. The VM hosts themselves also consist of failover-clusters. So we have: SQL on a cluster, which is built out of two nodes (each on a different VM host), Each host is running on a two-node hardware cluster. Belt-and-suspenders redundancy by design. My boss's boss wants me to discover whether this is too redundant - whether we are setting ourselves up for a glitch or failure, that should by common knowledge within the Windows and SQL Server community. Using Google, I haven't found much that would be definitive, or even an example of anyone else doing this. Anyone have experience or knowledgable opinions to share? Thanks, Mike Hinds
clusteringvirtualizationvm
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John Sansom answered
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PabloBrewster answered
Hi Mike, The new geo-clustering features in Windows Server 2008 R2 mean you no longer need a stretched v-lan to implement geo-clustering which works well with AlwaysOn availability groups. For example you have a 2 node cluster at site A and a two node cluster at site B which are part of the same cluster group and share an Availability Group Listener. Both nodes at each site share a SAN and can only failover between nodes at that site. AlwaysOn syncronizes the data with the primary site/primary node to the standby site/primary node. Depending on the performance you need from your database servers, running SQL in a VM has only very recently become really viable - http://www.brentozar.com/archive/2013/01/big-changes-for-big-virtual-machines-in-vmware-vsphere-5/. with the new vNUMA feature. There's a good book 'Pro SQL Server 2008 Failover Clustering' with a chapter on virtualization that might be useful for you. Hope this is useful, Paul
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