Raspberry/Navio/Ardupilot with readonly filesystem

Is this possible? I would like to make the Raspberry Pi/Navio combo as easy to use as an APM/Pixhawk. Are the dataflash logs the only thing that gets written to the sd-card? With APMCopter they only get written after arming. The wiki is not clear, if writing is finished with disarming. If so, they could be redirected to an usb-stick, without compromising the readonly filesystem. Did I forget anything?

APM writes logs and also parameters. So if you make a symlink /var/APM pointing to dir on USB Flash then it would be all good.

It is worth noting that we did flight tests with SD card extracted from the RPi after loading. Everything performed as usual, except there was no logs of course.

And how do you power off your Rpis? Through ssh every time? Or just unplug the flight battery?

Usually just unplugging the battery, haven’t had problems with that approach so far.

I once lost my rovers settings after just unplugging it. That is why I am looking for a save way to do it.

@schuermannsebastian, what kind of SD card do you have?

Kingston Class 10 16GB in the rover. Sandisk Class 10 16GB in the copter.

It’s just that here are some stories on the internet with Class 10 cards getting corrupted easily.

Ah ok. I may have a slower card somewhere. 8GB should also work, or not?

Actually high class cards are only faster on large file transfers. They could be worse in random access speed than cards of lower class. 8GB would be enough.

Sorry for ressurecting this thread. But I have had problems with data corruption in other SD based boards and they were solved by setting a decent journal size for ext4.

On the other hand what about using a guaranteed integretity filesystem, have you thought about zfs as a file system for the Navio Image?

@pneves That may be a good idea, we’ll think about it.