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The Stuff

I have the following components to work with:

  • two rooms
  • two beefy Dell R510s, one in each room
  • two EMC VNXe storage devices, one in each room.

The goal

Ensure that if one server room goes down, VMs can continue to come back up & function.

Thinking:

  • install Hyper-V on these two boxes
  • have one box failover to the other
  • abstract the two storage units away into one visible path so that if one goes down, the other can seamlessly fail over
  • take advantage of server 2012 to accomplish this

The questions

  • Can I use cluster shared volumes (CSVs) to accomplish this?

From my reading, it seems like I should be able to do the following:

  • install server 2012 on both boxes
  • create cluster shared volume comprised of an iSCSI locations on both EMC units
  • create

Apologies for the format; on mobile, will clean t up later.

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2 Answers

In order to support automatic failover of the VM's from one Hyper-V host to the other in the event of a host failure, you need to install the Failover Cluster feature on each Hyper-V host and create a cluster with these two hosts. Each host needs access to the VM storage for the VM's that you want to failover automatically. This is commonly done via iSCSI and Cluster Shared Volumes. How you would set that up with both storage arrays is a question for the storage vendor. If you can live without automatic failover then you could use Hyper-V Replica to handle the replication of the VM's from one host to another without using shared storage. You would set up one host in a single node cluster and leave the other host as a standalone Hyper-V host or you can create two independent Hyper-V clusters. The reason is because Hyper-V Replica works between cluster hosts and non-cluster hosts or between cluster hosts in different clusters. It does not work between hosts in the same cluster. Note that Hyper-V Replica doesn't support automatic failover for unplanned outages. If a host fails you'll have to manually failover to the VM's on the remaining host.

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pretty sure the emc's can do synchronous replication so I'd just configure this as a normal hyper-v cluster and probably wouldn't even use csv's in this case just let the san handle it. –  tony roth Apr 16 '13 at 19:03
    
Synchronous replication costs an arm and a leg on the storage- especially since this will be for one type of server only (Hyper-V), it makes sense to use the hypervisor to provide failover and clustering. –  Basil Apr 16 '13 at 19:59
    
sometime's I forget about costs.. But.. Sanbolics solution is fairly cheap and I'm pretty sure that it would work in this case. –  tony roth Apr 16 '13 at 20:29
    
@Basil also in this case the hypervisor won't cover failover and clustering since the rooms are independant, in this case a csv won't work. –  tony roth Apr 16 '13 at 20:37
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I spoke to EMC and they said this strategy should work, though they haven't officially written docs that support it yet.

Though I haven't put it into practice yet, the game plan is the following:

  • Create iSCSI servers on each EMC box, each with its own IP.
  • Create Hyper-V storage on each of those iSCSI servers
  • Configure a Hyper-V cluster with a CSV that points to both of those iSCSI locations

I'll update this answer with the exact process when it's completed.

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is this going to use san level replication then? –  tony roth Apr 17 '13 at 13:33
    
no; my entire endeavor is to avoid that. My understanding is that with SMB 3 + Mulipath I/O + CSVs, I can use 2 LUNs on my two different EMC devices to create a CSV. The CSV should leverage SMB 3.0 transparent failover. See channel9.msdn.com/Events/IT-Camps/… –  SeanKilleen Apr 18 '13 at 15:22
    
Without san replication it won't matter if you are using smb3 since the thing hosting it could be down completely. Now if you had san replication then one of the emc's could be down and you'd still be functional. –  tony roth Apr 18 '13 at 16:43
    
It's my understanding that by using a CSV as part of scale out file server, you're writing and reading to both SANs at the same time, and thus if one SAN goes down, it shouldn't matter because the CSV can still read and write data to the remaining san. So rather than using SAN replication, the OS is what's replicating the data across both SANs. I may not have it right but that's what I'm seeking to validate. –  SeanKilleen Apr 19 '13 at 13:41
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nope doesn't work that way, not unless you are saying its ok to lose some of the vm's. –  tony roth Apr 19 '13 at 14:11
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