52. Network (hosts) setting for mpich2 /mpd on debian

I have a switch with three computers attached two it. The ip addresses are static and are 192.168.1.1 (beryllium), 192.168.1.101 (boron), 192.168.1.102 (tantalum)

I use the computers to run nwchem across several nodes. The default /etc/chosts settings cause problems when trying to connect different instances of mpd on different nodes.

e.g.

beryllium: /etc/hosts

127.0.0.1 localhost  beryllium
192.168.1.101 boron
192.168.1.102 tantalum

Won't work, but 

127.0.0.1 localhost
192.168.1.1  beryllium
192.168.1.101 boron
192.168.1.102 tantalum

Will.

See for example:

Using /etc/hosts:

127.0.0.1 localhost  beryllium
192.168.1.101 boron
192.168.1.102 tantalum

me@tantalum:~$ mpdtrace -l

tantalum_51108 (192.168.1.102)

me@beryllium:~$ mpd --ncpus=6 -h 192.168.1.102 -p 51108 &

[2] 26283

me@tantalum:~$ mpdtrace -l

tantalum_51108 (192.168.1.102)
beryllium_38569 (127.0.0.1)

See the ip address (127.0.0.1)? tantalum sees 127.0.0.1, which is it's localhost (i.e. also tantalum). It should point at beryllium (192.168.1.1)

Using /etc/hosts:

127.0.0.1 localhost
192.168.1.1 beryllium
192.168.1.101 boron
192.168.1.102 tantalum

me@tantalum:~$ mpdtrace -l

tantalum_58007 (192.168.1.102)

me@beryllium:~$ mpd --ncpus=6 -h 192.168.1.102 -p 58007 &

[2] 26596

me@tantalum:~$ mpdtrace -l

tantalum_58007 (192.168.1.102)
beryllium_56234 (192.168.1.1)

And now it looks better.

"But /etc/hosts keeps changing on reboot!"

Which is because Network Manager keeps fiddling with it. Look at point 6 here http://verahill.blogspot.com/2012/01/debian-testing-64-wheezy-small-fixes.html

I haven't figured out how to do this via the command line yet.