A few days ago my root partition (formatted Reiser4) corrupted on my notebook. [ the usual IO hangups and nasty output in dmesg ]. Probably due to the usual wear and tear a notebook has to suffer or a faulty suspend cycle causing bogus IO. Something I suffered a few times before and didn’t think it would be a great deal. This time, though, fsck.reiser4 said it was all ok. That meant I was pretty screwed, for I knew it didn’t work correctly.
I lended a USB hdd, booted up to a fallback installation on a separate ext2 partition and tried to copy over everything to the USB hdd. It was quite tricky to copy over as much as I could and remembering the point where it started to crash when reading it. Luckily, I salvaged my whole /home. /var, /bin, /usr/share and a lot of other trees weren’t that lucky.
Formatted to XFS, copied everything I got back to the HDD and copied a Gentoo stage 3 tarball over it. A stage 3 tarball contains a minimal installation to which can be chrooted and then booted and from which the rest of the system can be build: the usual method to install Gentoo. I didn’t lost my world nor /etc/make.conf file. A small script later I got portage re-emerging every package I had installed on the system. Still 200 to go at the moment, but at least I’m now in a partially functioning gnome desktop, which is a lot more usable than TWM (ugly default WM of Xorg).
XFS performs quite well. It’s latency under load is a lot smaller than Reiser4’s. (It’s a pity I haven’t yet come to try the new patches in mm to help Reiser4 a bit with that problem. And also becasuse Reiser4 seems so close to inclusion, reading Andrew’s merge plans). In contrast, XFS sucks at handling a lot of small files compared to Reiser4. This is all just a feeling though. I haven’t tested anything. The most important characteristic of a FS, though, is only apparent after long use: the influence of fragmentation. Having looked around a bit, btrfs seems interesting.
On a sidenote on latency: my mom runs Ubuntu with EXT3 and even though EXT3 sucks in practically every single performance benchmark it has seem to got a superb responsiveness. Ah, 150 packages to go.