The summary.
WHAT A DATA CENTRE PROVIDES
Continuous power, controlled cooling, multiple network connections, physical security, and monitoring at all times.
Those are the things an ordinary building cannot guarantee — and power and cooling are the hardest of them.
WHEN YOU BUY HOSTING, YOU ARE BUYING THE FACILITY AS MUCH AS THE SERVER
POWER IS USUALLY THE BINDING CONSTRAINT, NOT SPACE
A rack is rarely filled to capacity because the power runs out first. Plan power per rack before counting units.
TRANSLATE ANY UPTIME FIGURE INTO PERMITTED DOWNTIME PER MONTH
The difference between figures that sound similar is substantial, and the remedy is usually service credits rather than compensation for lost trading.
Ask for actual outage history, not only the commitment.
CHECK THAT REDUNDANCY IS GENUINELY DIVERSE
Two fibre connections entering through the same duct fail together, and two providers using the same submarine cable are not diverse.
LOCATION DETERMINES SPEED
A distant server feels slow regardless of its specification, and a locally hosted site stays reachable to local users during an international cable fault.