Read-Only SD Card

If one needs a Raspberry Pi that shuts down save by just unplugging and without having the risk of corrupting the SD card one has to change the SD card to a read-only mode.


In the fstab:

$ sudo nano /etc/fstab

one has to change the SD card to read only (ro) and one has to make a temporary virtual drive (30MB), too:

/dev/mmcblk0p2  /               ext4    defaults,noatime,ro  0       1
tmpfs           /tmp            tmpfs   defaults,size=30M    0       0

Disable some Programs

One has to disable some programs, rsyslog and dphys-swapfile:

$ sudo systemctl disable rsyslog
$ sudo systemctl disable dphys-swapfile

If one needs a programs that requires writing one has to make sure that will be in the temporary drive. That could be done for example with a symbolic link:

$ ln -s /home/pi/tmp /tmp


For changes in the system one has to remount the partition writable:

$ sudo mount / -o remount,rw