This NSS module makes possible to use alternate passwd/shadow/group files
besides the system-specific files under /etc. The location of the alternate
files can be speficied by a symbolic link pointing from the hardcoded name
'/etc/cluster_rootdir' to the alternate root directory of the files. So if
you want to keep your alternate passwd/shadow/group files under
/gfs/cluster/etc, then create the link

# ln -s /gfs/cluster/etc /etc/cluster_rootdir

then put your (initial) cluster-wide passwd/shadow/group files with proper 
privileges into /gfs/cluster/etc and enable the modules in /etc/nsswitch.conf 
by the lines

passwd:         compat cluster_rootdir
group:          compat cluster_rootdir
shadow:         compat cluster_rootdir

The companion pam_unix module patches makes possible to use the alternate
files from PAM itself.

This software is almost a verbatim copy of 'nss-files' from glibc.
