we have a cluster of 3x DELL R630 servers with ESXi 5.5 and vCenter 5.5, shared storage connected diretly to each host via SAS cables to their HBA cards.
We want to create a new environment with vCenter 6.7U2 and of course ESXi 6.7U2. We have added 3 new DELL R640 servers in the same rack that will form a new cluster along with a new storage system that we connect to the new servers via ISCSI.
We plan to create new datastores on the new iSCSI storage and then map them to both the new cluster and the old one.
We do this because the old storage does not have free ports to connect the new servers to it and also the new servers don't have HBA cards.
But the old servers will be able to reach the new storage in ISCSI through the same switches.
Our plan, once we have both vCenters up and running, is to shutdown and remove from inventory the VMs from the old cluster one by one and then add them to the inventory of the new vCenter and power them on inside the new cluster.
However, two of these VMs are clustered with iSCSI bus sharing between them. Is it possible to move them one by one and avoid downtime for the applications? Or will I have to shut them down both and register them both to the vCenter before turning them on?