VMware has a vSAN witness appliance, which is basically an ESXi instance running in a VM to act as a witness. A witness host needs less capacity, bandwidth, and performance compared to hosts in normal vSAN clusters, or hosts in data center parts of the vSAN stretched cluster. A witness appliance stores the VM's witness components and is responsible for object quorums in the case of failure or a split-brain situation to make the required VM available.

The configuration of the witness appliance for a tiny environment are as follows:

• Tiny (10 VMs or less: application/domain controller/file and print server)
• Two vCPUs, 8 GB vRAM
• 8 GB ESXi Boot Disk, one 10 GB SSD, one 15 GB HDD
• Supports a maximum of 750 witness components