A lot of sites get 99.99% uptime easily. It's not difficult when you know what you're doing and have plenty redundancy. When you depend on any cloud stuff you can't do any kind of graceful degradation. Google goes down, you go down. Google goes bankrupt, you go bankrupt.
Considering how cheap dedicated servers are moving a service to the cloud makes little sense (exceptions notwithstanding).
99.99% is only 52 minutes of downtime a year... I don't think any of S3, Rackspace, Goole AppEngine, or even www.amazon.com have uptime that good this year.
Getting that kind of uptime is much harder than it sounds and for a lot of websites not worth the extra cost. How much money would pay to go from 99.9% uptime (~9 hours /year) to 99.99% (52 minutes)?
I disagree. For a small to medium size site, getting 99.99% uptime should basically be the default. If you have a competent staff and a decent provider, about the only thing that will take you down is a power/equipment failure at the DC - which does happen, from time to time, admittedly. Yeah, Rackspace had some problems this year, but most of the other tier 1 hosts have been rock solid.
Obviously it's more complex for a large site but for the vast majority I would say that level of uptime is the rule rather than the exception.
Three nines is pretty unacceptable in this day and age. Providers might only guarantee that level of uptime but if they really were down that much I'd run a mile. Netcraft is your friend!
How are you defining a site and uptime? Are you talking about dynamically switching systems to allow for upgrades without downtime?
I'm mostly wondering how it compares with the setup at my current location.
I have worked on systems that were designed for this, but I'm not sure if it's cost effective for most web applications. Most things can wait on occasion.
and what happens when an engineering fluke hits your KV store and locks it up. And it takes you 10hours to fix :)
You see your not actually paying for the 3 9's or the 5 9's. That is just corporate bullshit. Your paying for the promise that whatever the problem someone will be able to fix it in a few hours at most.
5 nines is not something you get on paper worth the ink normally. SLAs in the civil sector generally top out at 3 nines. Very, very rarely you talk about 4 and those are dealt out by the insurance company, not by the service provider.
I'm talking about real SLAs with compensation here, mind you, not the toilet paper you get from every cheapo ISP.
Considering how cheap dedicated servers are moving a service to the cloud makes little sense (exceptions notwithstanding).