In this blog, I would like to mark myself as a power-user of MMM. For more then 3 years now I'm engineering high-traffic websites and none of them was a small project. In the beginning I worked behind the livejasmin.com project (warning: NSFW!) which is an Alexa top100 site and now I'm working at ustream.tv which is in the top500 (so far). In this area, your greatest enemy is downtime. Thousands of users want to see your dynamic content by executing thousand of queries against your MySQL servers and what they don't have is the patience and they don't even tolerate critical security-upgrades. In both sites I mentioned above there is no point in time during the day at which less then 10k visitors are hitting the sites. Now one question comes up: How can you do an upgrade on your MySQL servers or how can you alter a larger table?
So you have a new feature and that means another index on a table or you just want to upgrade your application, there's no chance that your downtime will be hidden. We all know, even if you run your site with no downtime for months, 1 minute can make your bosses forget about that and ask you THE question: "What has happened?". If you would say: "There was no problem, I just took down the site to upgrade MySQL", you won't be the employee of the month.
So let's see how can MMM help: