Last month I converted my laptop to btrfs to get some experience using this new, still experimental file system. The bugs tell the story:

At this point I had a booting, working btrfs system. The bugs seen over the next weeks were strange:

In the meantime, I did some initial work toward supporting btrfs in d-i, writing a basic partman-btrfs. One of the interesting open questions is how best to use subvolumes to split up a single btrfs filesystem. If the installer defines the right set of subvolumes, upgrades to be rolled back, without also rolling back /home and /srv. The remaining parts needed for d-i to support btrfs are fairly tractable, but are waiting until root on btrfs is bootable, and until the filesystem is not experimental.

I gave up on the current experiement when I ran debsums on my laptop. (So that long thread was good for something!) It didn't find any corrupt files. But it did find a lot of md5sums files that were missing. Some of the packages with missing md5sums were upgraded just this week, and the md5sums files must have gone missing since.

I have not seen anything that I can say with certainty was caused by btrfs, and not by some other cause, but since I can't trust the data on this laptop now (although git tells me everything in my home directory is ok), I'm reinstalling it, and saying aloha to btrfs, for now.


Update: #575891 is a bug in dpkg that affects btrfs, and probably explains all the odd things I saw.

Missing md5sums files
It's not mandatory for packages to ship with md5sums files, so many of them don't. This is quite normal. The manual page for debsums even provides an example of how to configure an apt post-install hook to generate the missing md5sums files on the fly.
Comment by gedmin.as
comment 2
no, the hundreds of missing md5sums files were of packages that properly include them, such as my own package of debhelper
Comment by joey [kitenet.net]
verifying btrfs
Is it possible to set up some kind of partition replication where there are two partitions, one formatted with btrfs and the other formatted with a "trusted" format. Then everything written is written to both partitions. If one has any question about the validity of btrfs, one could check against the "trusted" format. Or periodically check to see if the data is identical on both partitions.
Comment by csights [myopenid.com]