Uptime

Uptime is the share of time a system is available and working, usually written as a percentage over a single month. It is the number every hosting company puts on its front page, and on its own it means very little. It starts to mean something only when you know what is being measured, and from where.

Turn the percentage into minutes and it suddenly becomes real. In a thirty-day month, 99% allows about seven hours offline, while 99.9% allows about 43 minutes. Go one step further to 99.99% and you are down to a little over four minutes. The first two look almost identical on a sales page, yet they separate a ruined afternoon from a short interruption nobody remembers.

The next question is what the check actually tests. A server answering a test and a customer finishing a payment are two very different claims. So a monitor that only asks for the home page will report a perfect month while the checkout has been broken since Tuesday. That is why, in a shop running on Storek, the check worth having is whether an order can be placed and paid for, not whether a page loaded.

Where the check runs from matters just as much. A monitor in the same building as the server will say everything is fine while customers in your own city cannot reach it. The fault is on the road between them, and nothing inside the building can see it. Ask how often the test runs as well, because one check every five minutes cannot see a 40-second outage that swallowed a hundred orders. Most outages are not a dead machine at all, but an expired certificate, a full disk, a domain nobody renewed, or a payment provider that is down while your server sits wide awake.

That is why Linkysoft measures the paying journey rather than the front page on the web applications we look after. It is also why our hosting and server reports separate real failures from planned work. When you compare suppliers, ask for last year's actual figures month by month, not the promise on the sales page. Then ask which minutes they leave out of the total, because that answer is usually the honest one. Linkysoft would rather show a client an honest 99.7% with the reasons than a rounded 100% nobody believes.