On 2/25/2012 6:16 PM, Brian J. Murrell wrote:

quoted

Others might know of a way of changing the allocation size to less than
1GB, but otherwise I recommend switching to something more stable like
ext4/reiserfs/etc.

So btrfs is still not yet suitable to be a root/usr/var filesystem, even
in kernel 3.0.0?

b.

Nope, still in heavy development, though you should upgrade to 3.2. 
Also, the devs mentioned in several places it's not friendly to small 
drives, and I'm pretty sure 5GB is considered tiny.

I don't think you need to separate /usr out to it's own disk. You could 
instead create a single drive with multiple subvolumes for /, /var, 
/usr, etc. When you have Ubuntu use btrfs for /, it creates @ and @home 
for / and /home, respectively, so it's a common phenomenon if you look 
for help.

--Farz