RSH scaling problems...

[David Mathog]

Here's a variant of rsh I've been experimenting with. 

ftp://saf.bio.caltech.edu/pub/software/linux_or_unix_tools/rsh.c

It allows multiple target nodes on the command line,
or multiple target nodes from a name file, and runs the same
command on each node (one after the other, not in parallel).

It also has a -z flag which disables all IO.  That mode can
be used to fire off jobs on remote nodes quickly in those
cases where no IO for that job must go through stdin/stdout/stderr.
I expect that the -z mode would not suffer (much) from the port
limitation Greg Lindahl points out since rsh -z doesn't leave
any ports open once it starts the remote command, and it typically
completes in about .011 seconds (100baseT, RH 7.3 on Athlon 2200).

I expect though that mpi probably does use stdout/stderr and maybe
stdin, so -z likely won't resolve the problem at hand.  

Still, it's a handy tool for tasks like:

 rsh -zf allnodes.txt killall pvmd3 \; rm -f /tmp/pvm\*

and the like.  

And it starts jobs at least 2x faster than any other tool
I've tried so far.

Regards

David Mathog
mathog at caltech.edu
Manager, Sequence Analysis Facility, Biology Division, Caltech