Stretched Cluster Witness? (not vSAN)

[mhost]

Probably an ignorant question, but here goes...

We are in the planning phase with a two-site DataCenter, with redundancy on storage (NetApp MetroCluster), Compute (vSphere) and Network (Cisco).
Our thought is a simple active/active setup, where everything runs as a "stretched cluster".

NetApp handles failover/isolation using a Witness Node on a 3rd site, which runs via a dedicated link to Site 1 and 2.
So storage should always be active on the right site - even if the redundant link between Site 1 and 2 breaks.

But what about VMWare?
To my knowledge, it is only in VSAN setup and/or HA-vCenter that there are Witness nodes?
So if we run a simple "Stretched cluster" with hosts and evenly distributed between Site 1 and 2 - without SRM and with just one vCenter for simplicity...
What happens if the link between Site 1 and 2 breaks, so the two sites are isolated?
Will HA see half of the hosts/VMs gone on both sites and try to start "missing" VMs?
Or can vCLS appliances help? If they are correctly distributed?

Best regards
Martin

[Duncan Epping]

I wrote a lengthy paper on the topic years ago: https://core.vmware.com/resource/vmware-vsphere-metro-storage-cluster-vmsc

What happens from a VMware perspective depends on where the VMs are located. Assuming the VMs align from a compute stance with the ownership from a storage point of view then NONE of the VMs will need to be restarted. If however your VMs are all over the place then VMs will be restarted as soon as VMware can acquire a lock on the datastore.

In other words, FOLLOW the guidance provided by NetApp and VMware to prevent ending up in a situation where VMs need to be restarted in this scenario. (https://kb.vmware.com/s/article/2031038)

[mhost]

Thank you so much Duncan!