A successful migration is orchestrated against common intuition: network first, the truck last.
- D-90: order the target site’s connectivity (transit, circuits, cross-connects) — these are the longest, least compressible lead times.
- D-60: handle IP continuity — with your own AS you re-announce your prefixes; otherwise a carrier present at both sites lets you keep your addresses (see avoiding renumbering).
- D-30: pre-synchronize data over a temporary link between old and new sites; lower DNS TTLs.
- D-day: cut over in batches, with go/no-go criteria and rollback ready. Aging hardware? Consider new or refurbished gear at the target rather than a risky transport.
The calmest variant: move your backup site first to the new data center, prove it under real conditions, then swap roles — no big bang.