Disk based systems can be configured with read-only root filesystems.
This provides added protection against accidental or malicious damage
by the user. Having a read-only root filesystem does
not preclude the use of a read-write user filesystem
in the same machine. All user data can be
stored on the user filesystem while still having the
protection of a read-only root filesystem.
NOTE:
If you configure a disk based system with a read/write root
filesystem, you will not be able to perform remote upgrades or re-installations
(unless you have the network computer upgrade tooling).
To upgrade a
client with a read/write root filesystem, you would have
to use a boot floppy and reinstall via a LAN connection
to an installation server.