On Jan 24, 2013, at 8:27 PM, Adam Williamson <awilliam@xxxxxxxxxx> wrote: >> > > Well that's not the one I was thinking of, actually - I believe I was > hit by cases where some subvols use redundancy, in which case df goes > completely wrong. I'd have to re-install and re-check to be sure of > exactly what I saw go wrong, though. Oh yeah that. Not sure what to fix here. df for Btrfs volumes is very literal, whereas df is actually fibbing when it comes to md raid1. And everyone is used to the fib. 2x 80GB virtual disks, mkfs.btrfs -d raid1 -m raid1: # df -h Filesystem Size Used Avail Use% Mounted on /dev/sdb 160G 56K 158G 1% /mnt Whereas, 3x 80GB virtual disks, mkfs.btrfs -d raid1 -m raid1: # df -h Filesystem Size Used Avail Use% Mounted on /dev/sdb 240G 56K 160G 1% /mnt The thing that makes this difficult, md arrays have a fixed raid level. Where as Btrfs volumes don't. Not implemented yet, but planned is per subvolume and per file raid levels, so in that case we have to be literal about the reported size of volume being the combined capacity of all block devices in the Btrfs volume. Or you get a real problem. Chris Murphy -- devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/devel
