[Beowulf] PVM says `PVM_ROOT not set..cant start pvmd` on remote computer

Robert G. Brown rgb at phy.duke.edu
Sun Mar 7 17:13:26 EST 2004


On Sun, 7 Mar 2004 mayank_kaushik at vsnl.net wrote:

> hi...
> 
> 
> im trying to make a two-machine PVM virtual machine. but im having problems with PVM.
> the names of the two machines are "mayank" and "manish".."mayank" runs fedora core 1, "manish" runs red hat linux -9..both are part of a simple 100mbps LAN, connected by a 100mbps switch.
> iv *disabled* the firewall on both machines.
> 
> iv installed pvm-3.4.4-14 on both machines.
> the problem is: 

> when i try to add "mayank" to the virtual machine from "manish" using
> "add mayank", pvm is unable to do so..gives an error message "cant start
> pvmd"..then it tries to diagnose what went wrong..it passes all tests
> but one -- says "PVM_ROOT" is set to "" on the target machine
> ("mayank")...but thats ABSURD..iv checked a mill-yun times, the said
> variable is correctly set..when i ssh to mayank from manish, and then
> echo $PVM_ROOT , i get the correct answer...

This COULD be associated with the order things like .bash_profile and so
forth are run for interactive shells vs login shells.

If you are setting PVM_ROOT in .bash_profile (so it would be correct on
a login) be sure to ALSO set it in .bashrc so that it is set for the
remote shell likely used to start PVM.  I haven't looked at the fedora
RPM so I don't know if /usr/bin/pvm is still a script that sets this
variable for you anyway.

> plz note that im using ssh instead of rsh, by changing the variable
> PVM_RSH=/usr/bin/ssh..since im more comfortable with ssh...

Me too.  ssh also has a very nice feature that permits an environment to
be set on the remote machine for non-interactive remote commands that
CAN be useful for PVM, although I think the stuff above might fix it.

> but when i try the opposite--adding "manish" to the virtual machine
> from "mayank" runnnig fedora..it works!

> furthermore....before i installed fedora core 1 on mayank, it too had
> red hat 9..and then i was getting the same problem from BOTH
> machines..but after installing fedora on mayank, things began to work
> from that end.

I've encountered a similar problem only once, trying to add nodes FROM a
wireless laptop.  Didn't work.  Adding the wireless laptop from anywhere
else worked fine, all systems RH 9 and clean (new) installs from RPM of
pvm, I explicitly set PVM_ROOT and PVM_RSH when logging in.  PVM_ROOT is
additionally set (correctly) by the /usr/bin/pvm command, which is
really a shell.

> what going on??? (apart from me whos going nuts)

Try checking your environment to make sure it is set for both a remote
command:

  ssh mayank echo "\$PVM_ROOT"

and in a remote login:

  ssh mayank

$ echo "$PVM_ROOT"

     rgb

> 
> 
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-- 
Robert G. Brown	                       http://www.phy.duke.edu/~rgb/
Duke University Dept. of Physics, Box 90305
Durham, N.C. 27708-0305
Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at phy.duke.edu



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