Making root's homedir persistent
The / directory of the ds101 and ds101g+ is in a ramdisk. Presumably to let the drive spin down properly. This also means that certain directories (like /bin, /dev/, etc.defaults) are lost when you power off or restart. The contents of the ramdisk are copied from /dev/hda4 on boot. So to make root's homedir "stick", do the following:
The DS101's /dev/hda4 (not sure about g+) seems to be persistent across reboots initiated by reboot command or holding down the power button. Afterwards, even if the unit is unplugged it seems to be persistent. The ramdisk and dev/hda4 seem to be in sync always with the following exception:
When it is not shutdown cleanly (eg. you cut power on the DS101 while it is booted and running) then on subsequent restart it appears to "reset" the entire /dev/hda4 to a stock configuration (presumably from flash?).
This needs more verification - need others to test and provide feedback.
The third way