Technology

Microsoft never promised where the nines would be

I see six

These services measure their uptimes in number of nines, the more the better.

When contracting a service, usually there are clauses that specify that it needs to be fully working and available x% of time, and compensation may be due in case this goal isn't met.

Let's say GitHub was down for 1 full day in the last year, that's 99.7% availability. That's "2 nines", but sometimes people might say "2 nines five", meaning "better than 99.5% uptime".

I'd say that the expectation for a high availability service nowadays is "5 nines": 99.999% uptime. That's around 5 minutes of downtime in a full year. This kind of performance from a site like GitHub is just unacceptable...

The graph is neat.

Saving some people a click: the cut-off y scale in the OP image is in 0.1% increments. So the lowest point is a little above 99.5%

No, it means you don't have outages. Ever.

No, that's infinite nines, which isn't possible.

Five-nines is something like 7 minutes of downtime throughout the entire year. At best, you might have automated failover systems that require tiny outages. No human involvement, though, unless you're deal with some major breakage that would have killed the five-nines commitment that year, anyway.

Yes, you have automated failover systems. But, if something happens which causes those systems to fail over, you need to immediately investigate what happened and why. Even at four nines you have automatic failover, redundant system, hot spares, etc. But, you accept that sometimes not everything will work as planned and you'll need to fix something. Five nines is just that and more.

It's takes a human something like 5-10 minutes just to get out of bed and figure out the situation, anyway.

Right, which is why I said that four nines is your realistic maximum if you're going to have people on call who aren't actually at their desks. To get better than four nines you need to have around the clock coverage with people at their desks so when a system breaks you have eyes on it in something like 30s.

How often is it offline outside the maintenance windows?

Yeah, maintenance windows are annoying, but they don't really count when describing the availability of a system. Many government systems are only available during normal business hours. That means they're offline for 16 hours per day. What matters is how available they are when they're supposed to be working.

For Elder Scrolls, two nines would mean that the game was allowed to be down for more than an hour a week outside of those maintenance windows. Or, if measured by quarters, which is more typical, the game would still have those maintenance windows, but, in addition, it might be down for a full day once per quarter.

Basically, the 8 hour windows every Monday is a trade-off so that the rest of the week is uninterrupted. They probably manage three nines the rest of the week by shifting any serious maintenance into the weekly downtime.

And, as for the game being "still popular", one site says that there are currently 7199 players in Elder Scrolls but more than 161k in World of Warcraft. It could be that part of the reason that World of Warcraft is more popular is that it doesn't have 8 hour maintenance windows every week, but it does often have 2+ hour windows. The number of players who are willing to put up with 8 hour maintenance windows every week seems pretty small.

It is still bad practice to select a narrow window from a axis like this and show the difference that seems massive relative to what is shown but isn't that significant when we can see the relation to the whole.

Graph 101

Unfortunately I have, my kid is absolutely fucking obsessed with it