2 Node vSAN cluster for Horizon supported solution?

[tonyvitek]

I have customer that is thinking of starting small with a Horizon/Horizon Apps solution, and they want to leverage vSAN for this. They currently have a 4node hybrid vSAN cluster and now we are thinking of starting with 2 hosts in a 2node(robo topology) All Flash vSAN cluster with the witness placed in the hybrid vSAN cluster. The plan is the use a seperate vCenter instance for the Horizon enviroment.

Q: Is this a supported solution?

Q: They are probably growing the cluster in time going from 2node(witness) to 4 host and beyond at a later stage, any insights or heads ups regarding this?

Any thoughts/insights are helpful.

Thanks!

[perthorn]

Cormac recently posted this blog post, which shows that what you are proposing should be a supported solution:

2-node vSAN topologies review - CormacHogan.com

The witness node is basically just as an ESXi host, so I believe they could easily just add 2 nodes to the cluster and remove the witness node in the future.

Thanks

Per

[perthorn]

and adding to that, I believe the witness appliance (which is basically an ESXi host) clearly has to be managed by the same vCenter that manages the 2 node cluster. But, it can still be located on a cluster that is managed by a different vCenter. You obviously need network connectivity between the 2 node cluster and the witness appliance and a max of 500ms latency.

[TheBobkin]

Hello Tony,

Yes of course this would be supported, this is what these are made for!

I would strongly advise against running the VM that backs the Witness Appliance on the vSAN nodes as any failure of one of the nodes/disk-group/disk will likely result in any FTT=1 Objects becoming non-functional (until the node/DG/disk comes back).

If you are rolling FTT=0 boxes then sure, whatever is on the remaining healthy host will still function in the above scenario.

Thus If possible just set-up the Witness VM on whatever datastore you have the vCenter running off, then register it as an Appliance in the vCenter being used to manage this cluster (In it's own Datacenter or the same Datacenter as the vSAN-nodes but NOT in the vCenter cluster these nodes are in).

Assuming both vSAN-nodes are local to each other (and you are using 6.5) you could implement this using Direct-Connect which removes the need for a lot of the networking hassle (but you will have to set this up later when transitioning to a 4-node setup:

https://blogs.vmware.com/virtualblocks/2016/10/18/2nodedirectconnect/

As Perthorn said, converting this to a standard cluster at later point would be just a case of adding the new vSAN-nodes to the existing cluster (and de-configuring the Fault Domains if you are not planning on splitting it 2+2, otherwise add one of each of the 2 new nodes to each of the existing FDs) then removing the Witness (assuming the 2 new nodes are on the same site!).

Bob

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