A 500-VM datacenter had to move to AWS within a 72-hour maintenance window with zero user-facing downtime. We chose CloudEndure for continuous block-level replication and staged cutover groups by application tier.
Pre-migration validation included DNS TTL reduction, connection draining tests, and rollback snapshots at each wave. Network connectivity used redundant Direct Connect links with BGP failover pre-tested in a shadow VPC.
All 500 VMs migrated successfully. Rollback was never triggered. The key lesson: invest 60% of the timeline in rehearsal and dependency mapping, not in the cutover itself.