I’m using 2.3R63-uNSLUng-6.8-beta on a brand new NSLU2. I experienced this same behavior after three different tries from a completely fresh install (I wiped sysconf with fis erase even). It is totally repeatable for me, every time. Do a df and let me know if it looks different for you from the one I posted in R63DiskBehaviour, ok?
Ped Xing