The legacy root squash mechanism relies on 2 parameters:

• the root_squash parameter specifies the UID and GID to which the root user is squashed when accessing the Lustre file system;
• the nosquash_nids parameter specifies the set of clients to which root squash does not apply.

This legacy mechanism has become redundant with the ability provided by the nodemap feature to implement root squash, in a much more flexible way.

So for newer Lustre versions, we would like to prevent setting the root_squash and nosquash_nids parameters on newly formatted file systems. On upgraded file systems, it would still be possible to change the already set values.