say enough for the guys at Contegix.Normally I never look forward to talking to the hosting guys, but ever since we have worked with Mathew Porter and his team, it has become a pleasure.They really go above and beyond.
Anyway, back to the move.Some of you will probably think that this is a no-brainer, but a few too many people were talking about sitting there doing the DNS switch and waiting for people to migrate over so I thought I would put up our process for moving.Note that we will use the term old server to mean the soon-to-be old server, and the new server to be the soon to be live and current server.
High level process, get the app running on the old and new boxes.Configure the old server for redirect mode.Configure the new server for live mode.
Do the switch, watch and see, get it running.Of course, the first step was to have migrated the application to the new machine, and run the battery of tests to make sure all is well.Part of this will involve a test plan of things to check off.You will also probably want to setup your /etc/hosts file to point to the new machine to do some testing to make sure that there are not any URL gliches it worked as m but not when it was live at m!
Redirect Mode, the magic is simple.At some point you need to tell DNS that your server is actually at a new location.We all know that it can take roughly up to 24 hours or so for this to propogate through the internet.There are some tricks such as taking the TTL down a notch (and making sure that gets through a cycle but it will still take time for the full propogation.You only want people going to ONE machine though, and as soon as you flip the switch, you want it to be the new machine.