installation help needed ...newbie

Robert G. Brown rgb at phy.duke.edu
Sun Mar 10 08:48:59 EST 2002


On Sat, 9 Mar 2002, rick bradshaw wrote:

> I have a small setup with redhat7.2. I used lam and MPI and ssh.
> here is a good link for using ssh without passwords
> 
> http://www.cs.umd.edu/~arun/misc/ssh.html
> 
> 
> and as for the other stuff like lam I setup the environment variable
> 
> LAMRSH='ssh -x'
> on all the machines. It seems to be working

Just to add to this -- one major advantage of ssh is that it is AFAIK
the only remote shell that allows an environment to be uniformly
exported to target machines from the originating machines.  If you put
lines like

PVM_ROOT=/usr/share/pvm3
PVM_RSH=/usr/bin/ssh
XPVM_ROOT=/usr/share/pvm3/xpvm
LAMRSH='ssh -x'

in ~/.ssh/environment, it will add these variables to the environment on
ALL target platforms when you ssh a command there.  One might still wish
for a global /etc/ssh/environment under root control, but root has other
ways to accomplish the same thing I suppose.

Believe it or not this can be incredibly useful.  A lot of "user
problems" with tools like pvm or lam occur when a user sets up the right
environment on one host but the cluster extends onto nodes where the
variables aren't correctly set and a user's normal home directory isn't
mounted (and its .bashrc or .cshrc environment) are not executed.  PVM
has even tried to fix at least one recurring version of the problem by
making the actual pvm command executed by the user a shell script that
sets their PVM_ROOT correctly, but it doesn't set or forward PVM_RSH, so
if you use ssh instead of the default rsh it often breaks anyway.

One of rsh's biggest weaknesses is its lack of environment forwarding.
I was struggling with crude hacks to "fix" this ten years ago (all of
which were incredibly ugly and tended to break a lot).

   rgb

-- 
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



_______________________________________________
Beowulf mailing list, Beowulf at beowulf.org
To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf



More information about the Beowulf mailing list