Reliability & Performance
SLA
A formal promise of a service's availability, usually with financial credits owed to you if the provider misses it.
An SLA is the contract that turns an uptime claim into an obligation. It states a target, say 99.99% availability, and specifies what you're owed when the provider misses it, typically service credits worth a slice of your bill. It's the difference between a host hoping to stay up and one that pays a penalty when it doesn't.
Read the fine print, because the details decide whether the promise means anything. What counts as downtime, how it's measured, whether scheduled maintenance is excluded, and how you have to claim credits all vary. A generous-sounding number attached to a narrow definition of "down" and a painful claims process is worth less than it looks. Credits also rarely cover what an outage actually costs your business.
An SLA is a floor and a signal, not a guarantee your site stays up. It tells you how seriously a provider takes reliability and what recourse you have, but the credit for a bad day never equals the revenue you lost. Design for the outage anyway.
Go deeper
- What an Uptime SLA Actually GuaranteesHow to read "99.9% uptime," what providers actually owe you when they miss it, and why the number matters less than the fine print.