I assume you are migrating to an Intel based Xserve….

Two things to do when migrating. If you are straight up replacing the server make sure all IP/DNS settings are set to your new server when you replace it, so you can just straight swap it out.

Also, do a full back up of Open Directory. This will require you put a password on the back up. It will archive all users, groups, and passwords. Also, on top of that export all your users and groups and computer lists to plain text as well (with out passwords) just in case your back up doesn’t sit well with the new OD server. Then worst case scenario you have to set a one time master password for your users and have it set to be changed at next log in.

All in all, it should go over smoothly.