Looking to see if the approach below is the best plan for a migration. Currently a 8 node vSAN 6.5 Stretched cluster is in place across 2 sites with windows vCenter 6.5 The plan is to purchase new hardware (8 new Hosts) then fit them into each site, install ESXi 7.0 onto them and then deploy a new VCSA 7.0, enable vSAN, setup fault domains etc.
So at this point the old and new vSAN will be sat side by side.
The VMs will then need to come over from the old vSAN to new vSAN.
Am I correct that we just need to ensure the VMware Management and vMotion networks can communicate from old cluster to new cluster so we can then perform vMotion and Storage vMotion of the machines from old to new cluster?
So we wont need both vCenters to be in the same SSO Domain or need any communication from old vSAN Layer2 Network to the new vSAN Cluster Network?
As what you are planning here is essentially a Storage vMotion of the data from one datastore and cluster to another, this won't require any form of connectivity between the vSAN networks in the clusters - just Management and vMotion networks.
To make things easier, you could potentially add the existing cluster to the new vCenter for duration of the migration.