[Beowulf] running out of rsh ports

[David Simas]

On Wed, May 03, 2006 at 02:14:31PM -0400, Joe Landman wrote:
> Dan Stromberg wrote:
> >On Wed, 2006-05-03 at 12:16 -0500, Bruce Allen wrote:
> >>rsh typically uses ports in the 513-1023 range.  With a 640 node cluster 
> >>we are running out of ports.  This leads to messages such as:
> >>"rcmd: socket: All ports in use"
> >>
> >>Are there any standard solutions to this other than 'use ssh'?  We 
> >>already have net.ipv4.tcp_tw_recycle = 1 in /etc/sysctl.conf
> >
> >http://dcs.nac.uci.edu/~strombrg/loop.html
> 
> Hmmm.... we use pdsh for our (customers) clusters.  Works quite well. 
> Your example
> 
> 	pdsh uname -a
> 
> does the same thing if it is setup right.

Except that it probably won't help with the problem, which I'm
guessing is caused by a given host attempting more than 1024
RSH connections to a given server in less than TCP TIME WAIT
seconds (minutes, whatever).  If the original correspondent
doesn't want to use SSH for RSH, which would fix things 
SSH isn't restricted to low-numbered ports, he could try to
re-implement his application in MPI.

DS


> 
> 
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> Joseph Landman, Ph.D
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> Scalable Informatics LLC,
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