[CentOS] groupadd failure

Wed Sep 2 20:42:29 UTC 2015
isdtor <isdtor at gmail.com>

The munin rpms from EPEL failed to install correctly on a particular
machine. This is why

# /usr/sbin/groupadd -r munin
groupadd: Can't get unique system GID (no more available GIDs)

but I don't understand why this happens. Even after checking the man pages
for groupadd and login.defs, I have been unable to determine what the
settings for SYS_GID_MIN/SYS_GID_MAX on RHEL/CentOS are. None of the 5/6
machines I have access to list them in login.defs. Even assuming
relatively conservative values of 201/499, resp. (examples from other
distros include 101/999), this doesn't add up.

# grep munin /etc/group
# ypmatch munin group
# wc -l /etc/group
100 /etc/group
# grep SYS_GID /etc/login.defs 

Any ideas? Information seems to be pretty thin on the ground.