Write filter

TwinCAT/BSD has a write filter that protects certain data sets against write access. The advantage of a write filter is that the user can secure a system in a preconfigured state. Following a restart, the system is automatically reset to the originally defined state.

The dataset zroot/ROOT/default, which contains most of the system and TwinCAT, is protected against write accesses when the Write filter is active. No other data sets are covered by the Write filter. For example, user files can still be persistently stored at /home or log files at /var/log, even if the rest of the system is reset after a restart.