On Sat, 2011-04-09 at 10:11 +0100, Hugo Mills wrote: > On Sat, Apr 09, 2011 at 08:25:00AM +0200, Helmut Hullen wrote: > > Hallo, linux-btrfs, > > > > First I create an array of 2 disks with > > > > mkfs.btrfs -d raid0 -m raid1 /dev/sdb1 /dev/sdd1 > > > > and mount it at /srv/MM. > > > > Then I fill it with about 1,6 TByte. > > And then I add /dev/sde1 via > > > > btrfs device add /dev/sde1 /srv/MM > > btrfs filesystem balance /srv/MM > > (it run about 20 hours) > > > > Then I work on it, copy some new files, delete some old files - all > > works well. Only > > > > df /srv/MM > > btrfs filesystem df /srv/MM > > > > show some completely wrong values: > It's not wrong -- it simply doesn't mean what you think it does. :) > > The total value in the output of "btrfs fi df" is the total space > allocated to block groups. As the filesystem needs more space, it > will allocate more block groups from the available raw storage pool, > and the number will go up. > > This is explained on the wiki at [1]. And I just drew up a picture which I think should help explain it a bit, too: http://www.kepstin.ca/dump/btrfs-alloc.png If I can figure out how to add images to the btrfs wiki, and find a good place to put it, do you think this would be a helpful addition? > [1] https://btrfs.wiki.kernel.org/index.php/FAQ#Why_does_df_show_incorrect_free_space_for_my_RAID_volume.3F -- Calvin Walton <calvin.walton@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
