We use NIS here with user `root' in almost every group in our NIS
/etc/group file. On our workstations, we cannot su to root:
/bin/su: cannot set groups: Invalid argument
I believe the problem is that there is a limit of 32 groups in glibc and
this is preventing me from su'ing to root.
This is actually kernel limitation. You can rebuild kernel (and glibc as well)
yourself to up that limit, in the kernel it is in linux/limits.h and asm/params.h,
in glibc you'll just need to make sure the updated kernel headers are installed
in the system before recompiling glibc. Note however that increasing that
value will eat up space in every tasks' task_struct.
It has no point in increasing this generally when 99.99% people will not need
it and it would just decrease the kernel stack for them.