Tools for the toolbox
I've moved my journal several times. I experimented with EditThisPage, with Blogger, and then with Radio Userland. I've not tried to maintain continuity, because each was an experiment. Indeed, my Blogger site is now 410 GONE. I've changed hosts from BestWeb to Pair after I bought my own domain, and in the course of doing so changed the underlying directory from radio to journal. And now, I'm changing it from journal to journal.
This change will not invalidate the previous URI. I've created a symbolic link between journal and journal, so as far as the operating system is concerned, those directories are the same. I'm also rewriting the URL. Tim Berners-Lee discussed why cool URIs don't change, and while there are a number of means for maintaining deprecated URIs, the important thing is planning a naming scheme. Cool URIs require forethought.
That doesn't happen.