Uptime
Uptime is the time during which a website, server or service is available and working, usually expressed as a percentage of a given period
What it means, how it is used and where it comes up, with its related concepts.
What it is and how it works
It is the basic availability metric; its opposite is downtime. Hosting and cloud providers usually commit to a minimum uptime in their service level agreements (SLAs), and compliance is checked with monitoring tools that query the service at regular intervals from different locations.
Differences that look small matter: 99.9% over a year allows around 8.8 hours of unavailability, whereas 99.99% cuts that margin to under an hour. It is worth checking what counts as an outage in each contract, as scheduled maintenance is often excluded.
Also known as
Availability
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