Fushigi said:
This would add to the cost, obviously, but it shouldn't be a dealbreaker. Maybe $250 or so to add the guts of 4 1GB CFII/SD cards to the circuit board + some firmware for the backup/restore.
That would be a dealbreaker, this is not a end all solution, its only
one component in an overall setup. It is designed to be as simple
as possible to allow for further backup/complexity to come from the
rest of the system.
Your suggestion only works as far as the assumption that you
could only put 4 1G sticks of RAM onto the board. If it is possible
to put more on there, then your backup is stuck, unless you
also want to try to compress the image from the main drive.
It would be easier to have a small hard drive in the system on standby, that is either mirroring the RAM disk in real time, or is set to dump an
image from the RAM disk as soon as the UPS kicks in.
Another option would be to connect a secondary battery unit to
the device, to provide a longer time to live for the existing data.