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. -- === Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk === PGP key: 515C238D from wwwkeys.eu.pgp.net or http://www.carfax.org.uk --- There are three mistaiks in this sentance. ---
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