Quoting "Avi Miller" <avi.miller@gmail.com>:
On 06/02/2012, at 12:24 AM, Russell Coker wrote:
It seems a bit bogus to report the Size of the filesystem as 4G when there are 2*2G devices in a RAID-1.
Perhaps you should watch my presentation on btrfs from linux.conf.au 2012[1]?
df lies, which is why you should run:
# btrfs fi df /mount
Instead. It'll show you properly what's being used by the btrfs filesystem.
Things are a bit confusing with "traditional" tools (as df), mainly because many subvolumes can share the same btrfs instance - so all show "x free GB" but it does not mean that there are many times "x GB" free. Still, the basics should get reported properly by df & Co. My brain just freezes at "many subvolumes share one btrfs instance", "many zfs sharing the same zvol" sounds much more intuitive. Regards Peter