On Mon, 3 Apr 2006, Christian Kauhaus wrote:
1. Put IPv[46] addresses into the machinefile. Since they are
protocol-specific, both rsh/ssh uses them just the way they are.
Yes, this would work. The machinefile could come from the user or from
a batch/queueing system, but this should signify that the producer
knows about the configuration of the machines and wants these specific
addresses to be used.
2. Put hostnames into the machinefile. Both rsh/ssh and OpenMPI perform
their own resolver lookup.
From what I understand, OpenMPI wants to have its daemons running on
the machines and then the interface configuration and communication
channel establishment follows, so the 2 phases are not connected to
each other.
The question is then what to do about the names given in the
machinefile ? Should they just be passed to the rsh/ssh client hoping
that they would work ? Should there be an option for resolving the
names to a user (or maybe admin) specific version of IP which should
then be passed to rsh/ssh ? Or should there be a list of IP addresses
that are tried in sequence ? Hmm, maybe all of the above, with some
means to choose between them ?
Your setup (IPv6 addresses given by the resolver, but no IPv6-aware ssh)
could be handled in both ways: either by putting numeric IPv4-addresses
into the machinefile, or by specifying 'ssh -4'.
Yes. Please keep in mind however that the opposite situation might
also occur (starting via IPv6, MPI communication via IPv4).
--
Bogdan Costescu
IWR - Interdisziplinaeres Zentrum fuer Wissenschaftliches Rechnen
Universitaet Heidelberg, INF 368, D-69120 Heidelberg, GERMANY
Telephone: +49 6221 54 8869, Telefax: +49 6221 54 8868
E-mail: bogdan.coste...@iwr.uni-heidelberg.de
