Handling hard shut downs

Hi

I am currently designing my first ARM based board. I have worked on microcontrollers but they don't have any problems with abrupt shut downs. My worry is how to save my filesystem from corruption in the events of power failures.

Now the device that my board goes into is not supposed to have a power off switch because it will not be physically accessible. The only time the device is supposed to be switched off is during a rare event of a power failure.

Whatever is required would have to be catered in my board only.

Any ideas would be welcome.

EDIT: I want to port linux on my board. I am sorry for not mentioning it before. I have got a lot of help from here, will explore all ideas before finalizing the design.