os2 free size on XO-1

[Yioryos Asprobounitis]

On a fresh install of os2 on the XO-1 I checked the available free space.
Connected to the network and rebooted after firmware update. Nothing else.

df says that /dev/ubi0_0 is 878MB, 595MB is used and 279MB is available. 
dd /dev/urandom writes 289.4 MB before "No space left on device"

Clear the dd written files, reboot and start copying files from a USB stick. Six tag.gz and squashfs files.
I copied 292.3 MB before "No space left on device"

So it would appear that the OLPC-11.3.0/os2 free space on the XO-1 is ~290MB.

Any suggestions before I start messing with the built, welcome ;)