Just had to take a moment to whine about the worst day of my internship. 

I was continuously interrupted yesterday morning (tax assessors, repairman - for needed repairs, etc.), and didn't get started until late.  So, feeling obligated, I worked late, and did something stupid.  I didn't realize how stupid until this morning, when my system wouldn't boot because it was unable to find the root directory of my logical volume.  About that point, I panicked - a seriously not useful response.

I built a thumb drive with a bootable ubuntu from my Windows PC  (with debian I would have had to install it).  Fortunately, all my files are still there, but I could only figure out how to access them from the File Manager.  I backed up the code I've written to 2 pen drives.

I took a bunch of walks.  Then I figured out how to access my files from Terminal, running as root.  Now I'm rebuilding Linux from what I got from the Torvald Linux github.   And I have a recipe for installing it so that's what will boot.

Before the next step, I think at the very least, I'll put everything (my files, Linux, xen, even /usr) back up on git, and, if I have to, I can restore everything, by re-installing, and getting stuff from git.  Not optimal, to say the least, especially so close to the end.