Graceful maintenance of web applications

Question

I asked this question on Stack Overflow and got some good responses. A couple of SO members mentioned I should ask it here also to see what the SysAdmin perspective on this is. So here goes:

I live in Australia (though this is probably true for most people in a non-US timezone) and am constantly greeted with "... is down for maintenance" right in the middle of my work day. In fact, in the last week we've had Google Wave, SO and Campfire all take turns going down. (Sad, Sad Panda :()

Being in Australia, the middle of the day on Monday, one of the busiest times of the week is normally when service operators based in the US (as it's Sunday night there) decide to do maintenance. I realise that services like SO and Google Wave are free so fair's fair but especially when Campfire went down I thought, "Surely we pay the same as any other client for this application and can therefore expect the same level of service?"

While I've worked developing web applications for a number of years, I've almost always worked on projects involving internal systems for a highly localised user base. So I've never had the "When's the best time to take the system down" issue.

But I wonder, is there a way to perform graceful maintenance of a web application? (let's assume it's something already in production state for simplicity) I'm sure there are SF members out there who have and do tackle this issue often... How do you do it? Is it possible not to adversely affect overseas users of your service?

FYI the SO question can be found here: http://stackoverflow.com/questions/2322599/graceful-maintenance-of-web-applications

Answer 1

Not that the decision is often up to me but but... At it's most basic I plot an hourly graph of usage for several weeks (or several months to ensure monthly cycles are considered) to find day of week and time with the least load, then I consider our clients and try to find a window where the least number and value of accounts is affected. (Yes. Some clients are worth more than others and some are easier to piss off than others.)

Note: At my company they write the maintenance window for each product into our contracts and notify our customers in advance if we expect an outage during an upcoming window. This allows your customers to know what level of availability to expect and to make plans for times when our services may be unavailable.