in vSAN environment, do we still need use HA or DRS? Why?

[david0531]

i am not so familiar with vSAN. 

in vSAN environment, do we still need use HA or DRS? Why?

Another question is , for a vSAN clustter of PFTT=1, how many VMDK copies exists  for a guest VM? assuming guest VM on host1, does only host 2 and 3 have a VMDK file of the guest VM? or all there hosts have?

Thanks

[TheBobkin]

 For HA, yes, assuming you want your VMs to get automatically restarted in the event of a host failure. Same for DRS, if you want automated balancing of VMs compute resources across the hosts then it should be enabled - the only thing different from any regular vSphere cluster is that SDRS doesn't apply to vsanDatastore.

 

A VM with FTT=1 policy applied to it only sees 1 vmdk per 'Hard Disk' but the Object backing this has 2 replicas + a witness-component distributed across all 3 hosts (e.g. 1 component on each).

[Duncan Epping]

I think Bobkin explained it right, but just to simplify things:

vSphere DRS = Load balances compute

vSphere HA = Provides recovery for failures for compute

vSAN = Distributed Storage Platform

So the three features focus on a different area of your environment.