You will need to go through full configuration on the 2nd ESRS, till you reach the Setup Complete page. An EMC employee (open a SR with support or ask your local CE) can then build a cluster from the first ESRS and add the second ESRS. The second will then download all managed devices from the backend. Cluster means, they share the devices they are managing and site IDs they are associated with. There are no shared resources like a witness share This is synced through the backend, so no need for the two VMs to be able to talk to each other. The VMs can have different settings for proxy, mailserver etc. to allow to avoid SPOFs.