VSAN Witness location in Virtual Centre

[mattriddler]

Hello,

I am a little confused over where the witness appliance should be located with regard to virtual centre.

My vSAN is a 2 node direct connected cluster with a witness in a different site.

Both the witness & the vSAN hosts are connected to the same Virtual Centre.

The vSAN hosts sit in their own datacentre & then a vSAN enabled cluster within that DataCentre.

The Witness sits in its own DataCentre (no cluster configured).

I have configured each of the hosts to send the witness traffic over the management network.

In the following post there is a video & it shows the witness in its own datacentre.

vSAN 2 Node with Direct Connect - Virtual Blocks

On the witness server I have the error 'Host with vSAN service enabled is not in the vCenter cluster'

The witness does not need to be in a vSAN enabled cluster (mine is in its own cluster (will have more witnesses soon)) that I am aware of.

Does this need to be in a vSAN enabled cluster?

Thanks,

Matt Riddler

[TheBobkin]

Hello Matt,

From your description you do appear to have it correctly configured - Witness in its own Datacenter directly under vCenter, vSAN data-nodes in a vSAN-enabled cluster in a Datacenter directly under vCenter.

I have not noticed this error message before and cannot seem to replicate it in a 6.5 HOL I just spun up.

Where are you seeing this error/alarm?

What version of ESXi and vCenter is in use here?

Is the Witness installed on a physical host or is it a Witness Appliance as a nested VM?

There are a few cosmetic issues resulting from Witness Appliance being treated like a regular ESXi/vSAN host so looks like this is another one.

Bob

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[ralfthiel]

Hi,

all of my vSAN Witness Appliances show the same message. All of them are 2-node clusters btw.

Ralf

[TheBobkin]

Hello Ralf/Matt

If you create a cluster (but do not enable vSAN on it) and place the Witness Appliance in the cluster, does the warning go away?

Basically this will tell us whether or not this is a new function of vCenter detecting vSAN-hosts not in clusters and I want to know if it checks whether it checks if vSAN is enabled on the cluster or not.

Bob

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[srodenburg]

I have the exact same error as the topic starter.

Topo:

8-node vSAN cluster in the main datacenter (datacenter A). Our vCenter (VCSA 6.5 U1) lives here.

A remote 2-node, v6.5 U1 direct-connect vSAN cluster (datacenter B)

A classic ESXi cluster in a 3rd datacenter (datacenter C) which hosts several witness-like appliances from various vendors). There is no vSAN here.

So I deployed the 6.5 U1 witness appliance in Datacenter C, added it to the cluster there and told the 2-node vSAN cluster in datacenter B to use that witness-appliance.

Result:  the witness-appliance complaining "Host with vSAN service enabled is not in the vCenter cluster".

What I think it complains about, if you take that message literally, is that it wants the witness appliance to live in the same cluster as where vCenter lives. In our case that would be Datacenter A. Why would it want that??

It makes no sense, so it smells like a bug to me.

[depping]

Are they part of the same virtual datacenter?

[sajjadsid]

I think it is a bit misleading. If you move the Witness Host out of the cluster and leave it on the Datacenter level the error will go away.  In 6.5, basically the warning shows when a host that has vSAN enabled sits on a vC cluster with no vSAN enabled. 

[Jasemccarty]

The vSAN Witness Appliance placement can be looked at from a couple different ways...

1. As a VM, it can reside in any cluster or standalone ESXi host (5.5 or higher) anywhere supported (OVH/vCloud Air, vCloud Air Network Partner, Hosted ESXi instances, Central Datacenter, ESXi Free, etc.). The only stipulation is that there must be connectivity to the Stretched Cluster/2 Node configuration the VM is supporting. This can be in the same vCenter (on a different cluster) or in a completely different environment.

2. As a Witness host, it has to reside in the same vCenter as the Stretched Cluster/2 Node that it is supporting. It cannot be added to the cluster that it is providing quorum to. It is a common recommendation to have vSAN (SC/2N) clusters in one or more "datacenters" (in the vSphere Web Client) and have one or more Witness Hosts (this case a VM) in a "Witness Datacenter".

The error that you are seeing is likely due to a versioning mismatch or other misconfiguration. Typically this error is seen when a host is part of a vSAN cluster, and then is taken out of the cluster. Remember that 2 Node Direct Connect with vSAN only works with 6.2 (Specifically vSphere 6.0 Patch 3 or higher) and vCenter must be a more recent build.

I'd suggest destroying that Witness Host VM and deploying a new one.

[ralfthiel]

Hello sajjadsid,

thanks for the information.

I can confirm the error disappears as soon as you move the Witness appliance out of the Cluster to the  Datacenter level and reappears as soon as you move it back to the cluster.

Tested with vSAN 6.5, 6.6 and 6.6.1

[hkg2581]

Hello All ,

It is recommended to place the witness (add the witness under the datacenter level and doesnot need a cluster for it) , when you add it in a cluster , the cluster sees it as a one node vSAN enabled cluster / network partitioned host in the same cluster hence the warning is triggered .