VSAN Witness options

[davel82]

Hi

I understand that a VSAN witness for a 2 node deployment can be either a physical host running the free version of ESXi (selected during VSAN 2 node setup, and not added to the cluster beforehand) - but it does require VSAN licensing.  The alternative is the VSAN witness appliance, which does not require a license.

Can you run a host, with the free version of vsphere, and run the witness appliance on it?

The scenario is I have a requirement for a secure site with a 2 node VSAN.  The witness will reside at the same site - however this will be a much smaller server and in an effort to keep costs down I would rather just virtualise it with a free copy of ESXi and run the witness appliance then on that host instead.

I cannot see any limitations to it working, but cannot see any clarification if its allowed....

[TheBobkin · Accepted solution]

Hello davel82​,

Yes it is "allowed" but note the CPU requirements for 6.7 also:

'VMware provides a vSAN Witness Appliance for those customers who do not wish to use a physical host for this role'...'This can include an ESXi Free licensed host'

vSAN Witness Host | vSAN Stretched Cluster Guide | VMware

Bob

[TheBobkin]

"a physical host running the free version of ESXi (selected during VSAN 2 node setup, and not added to the cluster beforehand) - but it does require VSAN licensing"

It doesn't require a vSAN license - only a vSphere license (whichever has the requirements you need as it can also run other VMs on it if required/capable) - vSAN licensing is always on the cluster-level, a standalone physical Witness doesn't need to be in a vSphere cluster.

Bob

[davel82]

Thanks for the reply - that does look to be correct.

In the VMware documentation regarding the Physical witness, it states the following: -

Licensing

If using a physical host as a vSAN Witness Host, it must be licensed with a valid vSphere license. This does not require the same licensed edition as the vSAN Cluster it is supporting.

Does the free esxi license qualify as a valid license, assuming that this host won't be used for any other purpose...

[TheBobkin]

"Does the free esxi license qualify as a valid license, assuming that this host won't be used for any other purpose..."

Yes, as per my first reply (and as noted in the referenced documentation).

Bob

[davel82]

Thanks - admittedly I didn't click the link on your first post and went straight to your second post, doh!

Thanks for your help, much appreciated

[skysunmonk]

but

If an ESXi host is licensed with the free version of the license key, you cannot add it to vCenter Server. This license does not contain the VirtualCenter Agent, which is necessary to manage a host with vCenter Server. This feature remains locked as long as the host is licensed with the free version of the license key.

To add ESXi hosts to vCenter Server, you must license the ESXi hosts with:

• vSphere Essentials
  
  Licensing an ESXi host with vSphere Essentials allows you to manage three ESXi hosts using vCenter Server. For more information on purchasing vSphere Essentials, see VMware vSphere and VMware vCenter Server Pricing.

• vSphere Standard, Enterprise, or Enterprise Plus
  
  Licensing the ESXi host with one these products unlocks the add-on features that allow you to manage ESXi hosts using vCenter Server. For more information about these products, see Compare vSphere Editions.

[skysunmonk]

which means the vSAN witness on the physical server cannot be add to the vcenter, but still can act as the vSAN witness host?

or we need base on the free license of ESXi to deploy a vSAN witness application which can be managed by vcenter ?

vSAN Witness Host

Both physical ESXi hosts and vSAN Witness Appliances (nested ESXi) are supported as a Stretched Cluster Witness Host.

VMware provides a vSAN Witness Appliance for those customers who do not wish to use a physical host for this role. The vSAN Witness Appliance must run on an ESXi 5.5* or higher host. This can include an ESXi Free licensed host, a vSphere licensed (ESXi) host, or a host residing in OVH (formerly vCloud Air), a vCloud Air Network (VCAN) partner, or any hosted ESXi installation.

vSAN Witness Connectivity

The vSAN Witness Host must be managed by the same vCenter Server managing the vSAN Cluster.

There must be connectivity between vCenter Server and the vSAN Witness Host in the same fashion as vCenter controlling other vSphere hosts.

The vSAN Witness Host must also have connectivity between the vSAN Witness Host and the vSAN nodes. This is typically performed through connectivity between the vSAN Witness Host vSAN VMkernel interface and the vSAN data network.

Thanks Bob

[TheBobkin]

@skysunmonk , You are correct, oversight on my part as yes indeed it does need to be in vCenter inventory to select as Witness node.

I reckon I was mixing up where you can run Witness appliance VM which you can of course run on an ESXi free and then register the appliance in vCenter inventory so it is still possibly useful (but with extra steps) as don't need some other paid license cluster/host to run the appliance on as 3rd site.

[ARM-IT]

An addendum for Essentials. 

Essentials edition vCentre has a host limitation of three entries in the inventory. The Witness appliance will consume one inventory item, therefore you cannot register the third host the Witness appliance would typically be deployed to, even though the third ESXi licence is valid. This is not a licence issue; this is a constraint of using Essentials edition vCentre. 

If you attempt to add the Witness appliance host, you will see an error stating: “This edition of vCentre only supports 3 host(s) in the inventory. Remove some hosts from the inventory before performing the operation.”

If you plan on managing all Essentials ESXi licenced hosts with the third ESXi as standalone, I recommend not deploying the witness appliance, use the third ESXi host as a traditional witness. This provides flexibility to add VMs to the Witness host, while still managed by the Essentials edition vCentre. 

The scenario where this would fit, when you need independent storage for recovery purposes on a third host, which also hosts the vSAN witness, while utilising Essentials ESXi licencing and Essentials edition vCentre.