Why is rocks-update out of sync on a couple of compute nodes?

Resolving The Problem

Why is rocks-update out of sync on a couple of compute nodes, and seems unable to bring them up to date?Basicly, rocks-update * will call yum to do the update,
for some reason, when yum do the update, it need to
try all the mount point, by strace the yum process:

[root@compute-0-0 ~]# ps -ef|grep yum
root 18732 18562 0 16:39 pts/2 00:00:02 /usr/bin/python /usr/bin/yum -y update
root 20748 20464 0 17:06 pts/7 00:00:00 grep yum
[root@compute-0-0 ~]# /tmp/strace -p 18732
Process 18732 attached - interrupt to quit
--- SIGSTOP (Stopped (signal)) @ 0 (0) ---
--- SIGSTOP (Stopped (signal)) @ 0 (0) ---
--- SIGINT (Interrupt) @ 0 (0) ---
rt_sigreturn(0x3b8fc618a0) = -1 EINTR (Interrupted system call)
--- SIGSTOP (Stopped (signal)) @ 0 (0) ---
--- SIGSTOP (Stopped (signal)) @ 0 (0) ---

And if yum hang, that's because the automount problem,
Need go those machines and kill hanging yum process.
after that, rocks-update works.

* This product includes software developed by the Rocks Cluster Group at the San Diego Supercomputer Center at the University of California, San Diego and its contributors.