Hi devs, I always had problems with aufs2 but during the recent rebuilds and KDE development it really annoyed me. It seems the aufs2 kernel module triggers all kinds of (not) so funny errors; especially on high I/O. E.g. building kdebase-workspace with makechrootpkg is a good idea to check i your filesystem or raid correctly recovers from a hard crash. Aside from FS and RAID errors I had funny segfaults of umount on reboot, massive system slowdowns etc.. In general I like the approach of makechrootpkg. Starting from a clean base chroot environment is a good idea to avoid all kinds of packaging issues. So I checked what other options there are. I thought it would be less problematic if it could be handled in userspace. There are solutions like unionfs-fuse; but unfortunately they are quite slow and cannot handle all kinds of special fiels we need (fiofos etc.) In the end I found a much simpler and cleaner way to handle this. All we want is to build our package in a clean chroot and revert all changes when building the next package. So why not just make just a copy of our base system, work on that and revert it when we are done. This can be easily done by changing this in makechrootpkg: mount -t aufs none -o "dirs=$chrootdir/$LAYER=rw:$chrootdir/root=ro" "$uniondir" to rsync -a --delete --progress -h -c -W "$chrootdir/root/" "$uniondir" On my system this sync takes less than 40 seconds in worst case (if uniondir is empty). On the other hand building the package is faster because there is no aufs overhead. And the best thing is that this cannot crash and freeze your system. :-) Pierre PS: We should probably get rid of aufs and merge this change into our devtools. -- Pierre Schmitz, https://users.archlinux.de/~pierre