A pre-move site survey documents both facilities before moving day: access paths, structural limits, power, cooling, network, a physically validated equipment inventory, and dependencies. Nearly every failed data center move traces back to something it missed. A circuit not where the drawings said. A doorway two inches narrower than the rack. A dependency nobody knew existed.
The site survey is the cheapest risk reduction available in a migration program. It is also the step most frequently compressed when schedules tighten.
What Is a Site Survey Actually For?
A site survey produces three things: an accurate physical picture of both facilities, a validated inventory of what is being moved, and a documented set of dependencies and constraints. Everything downstream — the move plan, the labor estimate, the cutover sequence — is built on that foundation.
Surveys that produce only a photo album and an equipment count have not done the job.
Physical Facility Documentation
Access and Path
Measure rather than assume. Drawings are frequently out of date and rarely reflect field conditions.
Route measurements
- Every doorway width and height along the intended path
- Corridor widths at the tightest point, including corners and turning radius
- Ceiling height and overhead obstructions such as ductwork, conduit, and sprinkler heads
- Ramp grades and transitions between floor surfaces
- Threshold heights and floor level changes
Vertical transport
- Freight elevator interior dimensions, door opening, and weight capacity
- Elevator availability windows and building management requirements
- Stair dimensions and landing space where elevators are unavailable
Dock and staging
- Loading dock height, leveler condition, and truck accessibility
- Available staging area square footage near the dock and near the data hall
- Parking and access restrictions, including time-of-day limitations
Structural Conditions
- Raised floor height, tile condition, and load rating
- Point-load limits and whether load-spreading plates are required
- Slab loading capacity where raised floor is absent
- Cable tray routing, fill levels, and available capacity
Infrastructure Documentation
Power
Power documentation is where surveys most often fall short. Record the actual state, not the intended design:
- Circuit inventory per cabinet, including breaker size, panel source, and phase
- Receptacle types physically present, verified visually
- PDU models, input requirements, and current load readings
- UPS capacity, runtime at current load, and battery condition
- Generator capacity, fuel supply, and transfer testing history
- Redundancy configuration and whether both feeds are genuinely independent
Take actual load readings rather than relying on nameplate ratings. Nameplate values overstate real draw substantially, and planning from them wastes destination capacity.
Cooling
- Cooling capacity and current heat load
- Airflow configuration, containment approach, and hot spots
- Humidity control against ASHRAE TC 9.9 ranges, and monitoring points
- Chilled water availability and loop specifications where applicable
Network and Connectivity
- Carrier circuits terminating in the facility, with circuit IDs and demarcation locations
- Cross-connects, patch panel assignments, and fiber counts
- Structured cabling standard (such as those published by BICSI), condition, and documentation accuracy
- Wireless coverage where operations depend on it
How Should the Equipment Inventory Be Validated?
The inventory must be validated physically, not exported from a CMDB and assumed correct.
Per asset
- Manufacturer, model, serial number, and asset tag
- Rack location by cabinet and U position
- Physical dimensions and weight
- Power requirements and actual connections
- Network connections with port-level detail
- Photographs of front, rear, and cable connections
Condition notes
- Pre-existing physical damage documented before the move begins
- Warranty and support status
- Equipment slated for decommissioning rather than relocation
Pre-existing damage documentation protects both parties. Without it, every scratch discovered at the destination becomes a dispute.
Why Map Dependencies During the Survey?
Physical documentation is only half the survey. The other half is understanding what depends on what.
- Application-to-server mapping including undocumented dependencies
- Network dependencies, including systems in other facilities
- Shared services such as authentication, DNS, time, and licensing
- Storage dependencies and replication relationships
- External integrations and partner connections
Interview application owners directly. Dependency documentation in most organizations is incomplete, and the gaps are exactly what causes cutover failures.
Operational and Compliance Constraints
- Change control windows and blackout periods
- Business cycle constraints such as month-end, quarter-end, or seasonal peaks
- Security clearance requirements and background check lead times
- Escort requirements for vendors and contractors
- Union labor requirements and jurisdiction rules
- Regulatory documentation obligations for the assets in scope
Clearance and badging lead times routinely surprise projects. Start that process at survey time, not at scheduling time.
Producing a Usable Deliverable
A survey deliverable should let someone who has never visited either site plan the move accurately. That means:
- Measured drawings or annotated floor plans rather than narrative descriptions
- A photo library organized by location and asset
- A validated inventory in a format the move workbook can consume
- An explicit constraints and risk register with owners assigned
- A gap list identifying anything that could not be verified
That last item matters. An honest survey says what it could not confirm. Unstated uncertainty becomes discovered risk on move night.
When Should the Site Survey Happen?
Conduct the survey early enough that findings can change the plan — typically eight to twelve weeks before execution for a facility-scale move. Re-verify critical measurements and destination readiness close to the move date, because facilities change. A survey conducted six months out and never revisited is a historical document, not a plan.