On Friday 27 November 2009 16:04:42 Hugo Mills wrote: > yOn Fri, Nov 27, 2009 at 03:41:17PM -0500, Jean-Philippe Robichaud wrote: > > Now I have 2 partitions (on 2 different sata disks) that are free for me > > to play with, each about 375 gb in size. I wanted to create a "raid1" > > volume using these two partitions, so I did: > > > > # mkfs.btrfs -d raid1 /dev/sda5 /dev/sdb5 > > # mount /dev/sda5 /btrfs > > > > and everything seems fine. > > > > Now what I find strange is that everything looks like a raid0 was > > created, not a raid1: > > > > $ df -h /btrfs/ > > Filesystem Size Used Avail Use% Mounted on > > /dev/sda5 684G 72G 612G 11% /btrfs > > > > What am I doing (or understanding) wrong? > > It's effectively showing you the number of unallocated blocks, so > (with a RAID-1, single-redundancy filesystem), files will appear to > take twice as much of your free space as you think they should: write > a 2GiB file to that filesystem, and free space will drop by 4GiB. > > I think that the reasoning behind this is that if you're using > per-object mirroring/striping, it's impossible to give a precise count > of the free space remaining on the volume in any meaningful way: write > a 1GiB striped file, and you'll take 1GiB of space; write the same > file mirrored, and you'll take 2GiB of space. > > Hugo. > Thanks for your input Hugo, but somehow it looks like something different is happening: du toto 1088 toto $ df . /dev/sda5 716579256 75455900 641123356 11% /btrfs $ cp toto toto2 $ btrfsctl -c . $ df . /dev/sda5 716579256 75456992 641122264 11% /btrfs So 1092 block were 'consumed', we're far from the +2000 I would have expected... Is there a place in /sys or /proc where I could perhaps get 'stats' about the btrfs volume? -- 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
