Re: transition RedHat-Debian

[Junichi Uekawa <dancer@netfort.gr.jp>]

Hi,

> We've been over this a few times on this list before; some argued a
> performance hit with ssh, others seem to think the hit is relatively
> small.  I personally use rsh on all of my group's clusters, noticed a
> huge hit at startup with ssh but haven't characterized the long-term
> impact.  But these clusters are all firewalled, and so have never had
> any problem (that I know of).  This would of course be foolish on
> net-exposed machines, unless you only allow rsh access to localhost.
> But if that's the case, perhaps you should use the mpich shmem packages.
> But those are only in unstable now, and dependent packages such as petsc
> and scalapack are only built against the rsh mpich packages...  I
> digress.

I cannot remember the details, since I've been away from doing
beowulf for a while, but I consider rsh limitation that it requires 
a privileged port on the originating server to be pretty much 
critical on larger installations.

Correct me if I'm wrong.

Every rsh session will use up one of the 1024 privileged 
port numbers from the originating host, 
so you will run out of them pretty quickly
if you're running several rsh sessions.



regards,
	junichi