I was attempting to migrate 2 virtual machines that are domain controllers between 2 datacentres running ESX 3.5 and ESX 4.1. I was advised to shut down both domain controller at the same time during the migration process. This is to avoid USN Rollback and other replication issues.

The following are the steps that I was planning to perform: 1. Shutdown both DC. 2. Copy both VMs files across to new datacentre using Veeam FastSCP (connection to both vCentre through IP address instead of hostname) 3. Power them up at new datacentre. 4. Configure Network interface/DNS/DHCP for both DCs in new datacentre

I have tried to use Veeam FastSCP rather than VMware Standalone Converter is because its copying rather than converting. Someone also suggested that I use backup and restore app like Veeam backup and replication software.

Sounds like a simple job, but after shutting down both DCs, the transfer rate using FastSCP is so slow registering only 1KB/s as oppose to the normal 1MB/s (or more).

When that attempt to transfer failed, I tried to cold clone both DCs resulted in the both ESX hosts get disconnected. I have tried troubleshooting by referring to this - VMware KB - Diagnosing an ESX Server that is Disconnected or Not Responding in VirtualCenter

It seems that the DNS being down is the caused of all unusual occurrence. The moment I powered up the DCs via VMware console command, the ESX host were able to connect to the vCentre again.

How can I avoid such a pitfall again? Am I doing it correctly? Any help would be greatly appreciated! Thank you.