As part of our continued efforts to improve the Zune Marketplace service onXbox LIVE, Zune Marketplace will be undergoing scheduled maintenance for up to 24 hours, starting 10:00 P.M. (PT) on January 25, 2010. During that time, you will be unable to rent or purchase video content.How is it o.k. for any major web business to go offline for up to 24 hours? How many people would have started using the Zune Marketplace on January 25th that never will now? I know, you're thinking nobody - except maybe this guy:
All joking aside, designing solutions to required downtime is not hard to do. I'm responsible for an online education site that can't have that many more users than the Zune. Yet, my team (which I'm sure is significantly smaller, but better looking than the team working on the Zune Marketplace) managed to release many times per week with only :30 mins of scheduled downtime for the entire year (the :30 mins was avoidable, but would've required ~3 days of work).
Typically, all you need to do is decouple client releases from application server releases from database releases. Then release in reverse order... required db changes go before application server releases go before client releases.
Now, we're starting work on a continuous deployment system so that all deployments happen on check-in. (Don't worry, there will be automated tests.) If you're a Microsoft engineer, read more at: Read Eric Ries's post on Continuous Deployment in 5 Easy Steps.