Since 1999, I’ve managed to migrate my Debian GNU/Linux workstation across hardware generations. The new machine is a tricked out Lenovo W540 with a really nice 2880x1620 IPS panel, a SSD and 16G RAM. A really nice machine. This time the task was a bit more complex than usual, as I chose to inflict multiple complexities upon myself:

  • BIOS -> UEFI

  • ext4 -> btrfs migration

  • desktop -> laptop
  • nvidia only -> bumblebee/optimus

  • 200dpi screen

  • systemd

Here is my tale.

BIOS, partitioning and filesystem: the transfer

I did a test installation of Debian testing on the new machine to check out what works and what doesn’t. UEFI support worked really well and provided a branded entry to boot debian from the UEFI menu. Also this prepared the SSD with proper partitions.

I’ve wanted to try out btrfs for quite a while now and the time seemd ripe. I did the test installation already to a btrfs volume and that worked fine.

On the downside all tohse changes meant that I could not just dd over the whole disk and be done, but needed a file-level solution. After some fiddling and false-starts, I settled on booting the laptop into the debian-installer (netinst, teesting) rescue mode and the old desktop with the current grml 2014.10-rc1. The d-i on the target was able to start a shell in the target system that was able to run update-grub successfully after the transfer to fixup the grub config. Grml on the desktop is just really nice to have a quick sshd running while having no traffic on the source partition.

Transferring the actual data was accomplished by running

rsync -avx --delete --numeric-ids root@DESKTOP:/mnt/ /

from the d-i chroot shell. The source partition was mounted on /mnt in the grml.

After the transfer, /etc/fstab needs fixing to have the right device name and fstype specified for root. Debian’s default of using UUIDs doesn’t help much, when transplanting onto different partitions.

From the test installation the target had already an UEFI partition with installed grub loader. The source system was lacking the actual binaries to finish booting the system. Confusingly, the grub-efi-amd64-bin package delivers the loader mods to /usr/lib/grub/x86_64-efi, while the booting grub expects them in /boot/grub/x86_64-efi. The test installation had them there, so I assume that there is some process I missed, which installs the on demand. I did so manually to good effect. I totally exepct this to break in a few years when a incomatible grub updates comes along and finds that I forgot to update some weird config file.

I ran

update-grub
update-initramfs -k all -u

to get all the fancy new stuff to boot.

The System

Now that the system boots, I quickly noticed two things: I had reused the MAC adress of the virtualisation bridge I had configured and X didn’t work.

Thanks to the detailled notes for running Debian on a W540, getting X to run was quite easy: I installed the bumblebee and primus utilities, killed the old nvidia xorg.conf and off it went.

The problem with the re-used MAC adress is not really a problem as the old system will be re-purposed for a different project, which will include a fresh install anyways. But I wanted to get to the gorund of this, as I was not aware of this MAC adress persiting thingy. Turns out that systemd-networkd, which I used to configure this bridge, computes a “static” MAC adress from /etc/machine-id and the interface’s name. Resetting the machine id requires the following steps:

rm /var/lib/dbus/machine-id /etc/machine-id
dbus-uuidgen --ensure
systemd-machine-id-setup

and a reboot.

200dpi

The new screen is absolutely gorgeous. As LWN reports high dpi support on the desktop is spotty. I use the i3wm as desktop environment and the 2880px horizontal space mean, that I can now have two 1024+px windows side-by-side, which is really nice as those pesky repsonsive design webpages now do not reformat. On the downside, the text is quite small, so while it is good, it’s not as good as I expected. Iceweasel and icedove have a weird multiple-personalities disorder: icons and content seem to be rendered in pixels, while UI-text is rendered dpi independently. I guess I’ll find some tweak somewhere to improve that, but for today I’ve fiddled with this enough, and I’ll live through a bit of ugliness.