[Beowulf] MPICH config: DCHP addresses and /etc/hosts?

Nathan Moore nmoore at winona.edu
Thu Jul 27 19:02:02 EDT 2006


Hello,

I've downloaded and compiled MPICH2 on a small cluster of PowerPC's  
running linux (YDL 4.1).  The cluster has home directories served  
through NFS and common login accounts via NIS, with one of the  
cluster nodes acting as the NFS/NIS server.

The machines reside on a campus network with IP addresses assigned  
through DHCP.  Accordingly, I've left the /etc/exports file alone,

	[root at muscovey ~]# cat /etc/hosts
	# Do not remove the following line, or various programs
	# that require network functionality will fail.
	127.0.0.1               muscovey localhost.localdomain localhost

While I've been able to get MPICH "mpd" deamon to run on a single  
node, communication within the MPICH ring fails.  The error I've seen  
with mpdcheck follows,

[root at muscovey ~]# mpdcheck -l

     **********
     Your fully qualified hostname seems to be set to 'localhost'.
     This generally means that your machine's /etc/hosts file  
contains a line
     similar to this:
127.0.0.1 mybox1 localhost.localdomain localhost
     You probably want to remove your hostname from this line and  
place it on
     a line by itself with your ipaddress, like this:
$ipaddr mybox1
     **********

     **********
     Your unqualified hostname resolves to 127.0.0.1, which is
     the IP address reserved for localhost. This likely means that
     you have a line similar to this one in your /etc/hosts file:
     127.0.0.1   $uqhn
     This should perhaps be changed to the following:
     127.0.0.1   localhost.localdomain localhost

On my campus network, IP addresses are assigned by DHCP.  To my  
knowledge, this precludes the sort of "normal" /etc/hosts file like  
the one following,

[root at muscovey ~]# cat /etc/hosts.novel
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1               localhost.localdomain localhost
199.17.152.135          muscovey.workstations.winona.edu muscovey

where 199.17.152.135 is found through ifconfig -a, and accordingly, I  
seem to be stuck with an /etc/hosts like,

Is there a workaround in /etc/hosts that allows only hostnames to be  
specified?  What is the proper format for /etc/hosts?  Alternatively,  
how should MPICH be configured for DHCP (rather than static IP)?

- - - - - - - - - - - - - - - - - - - - - - -
Nathan Moore
Physics
Winona State University
AIM:nmoorewsu



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