Seconded
I completely and utterly agree with you. People think that uber uptime is trivial, and it simply is not. "5 nines" is the pinnacle, which is 99.999% uptime. If you do the maths here, you get 53 MINUTES of downtime. 5 nines is always quoted against the full year, not "unscheduled downtime." That would mean that all upgrades you ever wanted to do, plus an allowance for some unexpected downtime had to fit into 53 minutes a year. I design and build trading systems and I know from first hand experience that each nine is exponentially harder than the last to achieve. The fifth nine is _incredibly_ hard, and _incredibly expensive._ For a trading system, we do it. For a $99 a year consumer service, no way. You wouldn't make money given the costs. When you shoot for 99%, you code for reliability. When you shoot for 99.999%, you are incredibly hand tied in terms of architecture. You have to be able to bounce one node of a cluster without bringing them all down, and handle the associated issues with the fact that the code bases will be different on different nodes for a short time. That's not easy to handle and you end up putting a TON of time into handling a time window that if you could only take all the servers down for an hour, you wouldn't have to cope with. The difference between 99% and 99.999% is night and day. And 99.9999%. That doesn't exist. If it does, it's not economically viable.
99% uptime, on the other hand means you can have 3.65 DAYS of downtime, which is probably OK, given maintenance, and given that "down" usually means totally, whereas mobileme, like many things, is a series of services that don't all have to come down at the same time...
For a consumer service, 99% seems about right. Which of course, does not excuse the fact, that right now they have blown that completely too, at least for email. They can fudge the statistics though. Mail is down, but everything else is working, so is it 5 days of downtime for mobileme, or 5 days adjusted for it just being mail...
be well
t
Your figure of 0.0001% means uptime of 99.9999% - no one achieves that.
Having RAID and a decent backup system is only a small part of what you need to achieve high availability - non interruptible power supply, full hardware and network redundancy, fallback sites and so on.
Again, expecting or trying to achieve a high level of availability for what is a budget web hosting service is just plain stupid.
I completely and utterly agree with you. People think that uber uptime is trivial, and it simply is not. "5 nines" is the pinnacle, which is 99.999% uptime. If you do the maths here, you get 53 MINUTES of downtime. 5 nines is always quoted against the full year, not "unscheduled downtime." That would mean that all upgrades you ever wanted to do, plus an allowance for some unexpected downtime had to fit into 53 minutes a year. I design and build trading systems and I know from first hand experience that each nine is exponentially harder than the last to achieve. The fifth nine is _incredibly_ hard, and _incredibly expensive._ For a trading system, we do it. For a $99 a year consumer service, no way. You wouldn't make money given the costs. When you shoot for 99%, you code for reliability. When you shoot for 99.999%, you are incredibly hand tied in terms of architecture. You have to be able to bounce one node of a cluster without bringing them all down, and handle the associated issues with the fact that the code bases will be different on different nodes for a short time. That's not easy to handle and you end up putting a TON of time into handling a time window that if you could only take all the servers down for an hour, you wouldn't have to cope with. The difference between 99% and 99.999% is night and day. And 99.9999%. That doesn't exist. If it does, it's not economically viable.
99% uptime, on the other hand means you can have 3.65 DAYS of downtime, which is probably OK, given maintenance, and given that "down" usually means totally, whereas mobileme, like many things, is a series of services that don't all have to come down at the same time...
For a consumer service, 99% seems about right. Which of course, does not excuse the fact, that right now they have blown that completely too, at least for email. They can fudge the statistics though. Mail is down, but everything else is working, so is it 5 days of downtime for mobileme, or 5 days adjusted for it just being mail...
be well
t