Someone asked this question on VMTN this week and I received a similar question this week from another user… If you disconnect a host from a VSAN cluster it doesn’t change the total amount of available capacity. The customer was wondering why this was. Well the answer is simple: You are not disconnecting the host from your VSAN cluster, but you are rather disconnecting it from vCenter Server instead! (In contrary to HA and DRS by the way) In other words: your VSAN host is still providing storage to the VSAN datastore when it is disconnected.
If you want a host to leave a VSAN cluster you have two options in my opinion:
- Place it in maintenance mode with full data migration and remove it from the cluster
- Run the following command from the ESXi command line:
esxcli vsan cluster leave
Please keep that in mind when you do maintenance… Do not use “disconnect” but actually remove the host from the cluster if you do not want it to participate in VSAN any longer.