I’ve worked on services with 5 nines of availability (i.e. 99.999% available, less than 5 minutes of downtime allowed per year). I’ve more frequently worked on ones with 4 nines, where you’re allowed almost an hour of downtime per year. GitHub is now barely maintaining 2 nines. That’s just embarrassing.
Each “nine” you add is much more difficult. To get four nines you need people on call who can start working on a problem within 5 minutes and fix it within a few more minutes, and you can only get those calls once every couple of months. Five nines means that you need people at their desks in shifts ready to start fixing something the moment there’s a problem because it would take too long for someone on-call to get their computer out, connect and authenticate. It requires warm backup systems that are sitting idle but ready to take over fully at a moment’s notice.
A two nines system is allowed to be down for 100x as long as a four nines system, and 1000x as long as a five nines system. It’s almost 15 minutes of downtime allowed per day, compared to about 15 minutes every 3 months for a four-nines system. Gamers wouldn’t even put up with a two-nines system for a video game. It’s absurd to allow that for a critical piece of infrastructure for software.
Five nines means that you need people at their desks in shifts ready to start fixing something the moment there’s a problem
No, it means you don’t have outages. Ever.
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.
It’s takes a human something like 5-10 minutes just to get out of bed and figure out the situation, anyway.
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.
I’ve worked on services with 5 nines of availability (i.e. 99.999% available, less than 5 minutes of downtime allowed per year). I’ve more frequently worked on ones with 4 nines, where you’re allowed almost an hour of downtime per year. GitHub is now barely maintaining 2 nines. That’s just embarrassing.
Each “nine” you add is much more difficult. To get four nines you need people on call who can start working on a problem within 5 minutes and fix it within a few more minutes, and you can only get those calls once every couple of months. Five nines means that you need people at their desks in shifts ready to start fixing something the moment there’s a problem because it would take too long for someone on-call to get their computer out, connect and authenticate. It requires warm backup systems that are sitting idle but ready to take over fully at a moment’s notice.
A two nines system is allowed to be down for 100x as long as a four nines system, and 1000x as long as a five nines system. It’s almost 15 minutes of downtime allowed per day, compared to about 15 minutes every 3 months for a four-nines system. Gamers wouldn’t even put up with a two-nines system for a video game. It’s absurd to allow that for a critical piece of infrastructure for software.
No, it means you don’t have outages. Ever.
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.
It’s takes a human something like 5-10 minutes just to get out of bed and figure out the situation, anyway.
No, that’s infinite nines, which isn’t possible.
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.
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.
It’s not impossible. Large reliable websites do it all the time. It’s call 100% uptime.
Sure, it’s measured per year, and sometimes they have some outage that breaks the record. But, it is possible to have 100% uptime throughout the year.
I’m used to environments where they expect five nines, get 3 (maybe 4) nines, and fund for 1 nine.