Currently learning about vSan. I have some questions.
Is is best practice to also have running VM's on the VSAN host?
I would like to create a 2 node stretched vsan cluster with 1 witness node.
So one VSAN in location A and one VSAN in location B.
Configure HA on the nodes hosting the VM's.
Thanks for the help.
"Is is best practice to also have running VM's on the VSAN host?"
I am not really sure what the point of having hosts at all would be if you were not going to run VMs on them!
"How much data loss will i have when a ESXi host in location A goes down."
So the main point of 2-node clusters (and vSAN in general for the most part) is that data has some redundancy and is not lost when a single node/disk/Disk-Group becomes unavailable - think of it as RAID1 across nodes, with a replica of all data stored on each node and small metadata stored on the witness (only used as a tie-breaker). Thus if you have standard FTT=1 Storage Policy applied to the data then no data will be lost.
"Will the data replication between the 2 vSan nodes be synchronized a a-synchonized?"
Synchronous - IOs are not committed until cache-tier on both nodes writes the data and acks.
"Where do i place the witness node?"
Anywhere really (except on the data-nodes) - this doesn't have beefy hardware nor low-latency network requirements, typically vSAN customers run these in the cloud or on some other VMFS/vSAN infrastructure.