On Thu, Jul 19, 2012 at 7:39 PM, Shavi N [off-list ref] wrote:

So btrfs gives a massive difference locally, but that still doesn't
explain the slow transfer speeds.
Is there a way to test this?

I'd try with real data, not /dev/zero. e.g:
dd_rescue -b 1M -m 1.4G /dev/sda testfile.img

... or use whatever non-zero data source you have. dd_rescue will give
a nice progress bar and speed indicator.

Also, run "iostat -mx 3" while you're running dd, and while accessing
it from samba. In my experice, btrfs is simply slower than ext4.
Period. There's no way around it for now.

-- 
Fajar