[MPICH] Running on root's MPD as either root or another user

[Matthew Chambers]

Hi all,

The install guide seems unclear about how to do this or if it's even 
possible.  I have my user's .mpd.conf as:
MPD_SECRETWORD=foo
MPD_USE_ROOT_MPD=1

And my /etc/mpd.conf is:
MPD_SECRETWORD=foo

Permissions on the user's conf are: -rwx------

When permissions on the /etc/mpd.conf are: -rwx------
I can run mpdtrace and MPI jobs as root just fine, but when I try either 
of those as the user, I get "open failed for root's mpd conf 
filempdtrace: mpd_uncaught_except_tb handling"

So when I set permissions on the /etc/mpd.conf are: -rwx---r--
I can run mpdtrace as the user, but when I try to run an MPI job (e.g. 
mpiexec -n 16 hostname ; not an MPI program, but still works fine with 
MPICH2), it hangs.  When I break it with CTRL-C I get the message 
"(mpiexec 413): mpiexec: failed to obtain sock from manager".  I can't 
run mpdtrace or MPI jobs as root because of: "configuration file 
/etc/mpd.conf is accessible by others \ change permissions to allow read 
and write access only by you".  This seems a bit of a catch-22.

I'm mostly interested in getting it working for the user.  I don't have 
the MPD binaries installed in the standard location, so I'm not sure how 
to set the permissions.  I tried setting everything to: -rwxr-sr-x
But that has the same error.  The user only has an account on the head 
node, is that the problem?

Thanks,
Matt Chambers