myCNC Online Documentation

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======Changing the read-only system behaviour on Raspberry Pi======

All recent versions of the OS image for Raspberry Pi are using the ''overlayroot'' functionality, as a result of which the system partition of the disk works in **read-only mode**. In this way, the partition is protected from the user writing to it, which significantly increases the lifetime of the SD card installed in the Raspberry Pi.

The ''overlayroot'' creates an overlay (combining 2 partitions) - one of which is on the disk and the other in RAM. The "read from disk" behaviour is unchanged, while the "write" behaviour is instead configured to write to the RAM section. Therefore, remounting the read-only section for writing does not solve the issue, as the system will still write new files to RAM.

The method that should be used instead is to remount the "write"-section and then to correct the configuration file in it by disabling ''overlayroot'', after which the system should be rebooted.

Therefore, if you need to make changes to the disk (for example, in order to install updates), you can bring the system back to normal read-write mode. To do so: 

1) Navigate to the //ADMIN// folder on your desktop:

{{:troubleshooting:read-only-001-admin.png}}

The folder should contain the ''read-write.sh'' and ''read-only.sh'' files:

{{:troubleshooting:read-only-002-scripts.png}}

2) Run the ''read-write.sh'' script:

{{:troubleshooting:read-only-003-run.png}}

3) After rebooting, the system will be read-write mode.

4) To switch back to the write-only protection mode, use the ''read-only.sh'' script instead.