[Beowulf] KVM to a compute node - ssh

Michael Will mwill at penguincomputing.com
Thu Jun 3 09:59:41 PDT 2004

On Thursday 03 June 2004 09:19 am, Robert G. Brown wrote:
> On Thu, 3 Jun 2004, Guy Coates wrote:
> > > PCs, even "server class" motherboard PCs, alas, have never been
> > > designed to have a "real" serial console as video cards are viewed to
> > > be essential, not optional.
> > >
> > > image.  This is a BETTER solution than a serial interface for this
> > > purpose, as serial interfaces to my experience have a real problem
> > > interpreting e.g. three finger salutes in all possible runtime states
> >
> > Ok, I admit plain serial does have its limitations on PC hardware.
> Ya, and WOL isn't perfect or even all that great for this as well -- it
> isn't really designed to overcome post boot state from what I can tell
> from the original AMD white paper, and so while it can power a system on
> from off, it isn't clear that it can reboot a hung system. 

We solved it by putting a small serial remote control card into the boxes that 
simulates pressing the power and reset buttons. It sits between the serial 
port and the mainboard and sniffes for break+command on the serial port 
without affecting its normal use. We use cyclades terminal servers to be able 
to connect to each node so we can adjust bioses without having to go to the 
KVM, and with help of the remote control card also are able to power it up 
and down as we like, even if it is completely stuck.

> > The management processor is pretty clever; if it notices something on the
> > ILO or serial port it automatically changes the BIOS interface into its
> > command line version, and spits all its post stuff etc onto the ILO or
> > serial port. You can set user defined escape characters to send those
> > awkward CTRL-ALT-DELETE or magic SYSRQ sequences.
> >
> > You get the best of both worlds; command line driven, out of band
> > management, a real console, but going across the network rather than
> > through an expensive terminal server.
> >
> > Drawbacks; it is HP only, and I don't know if it is IPMI compliant. A
> > similar management interface that is the same on *all* pc hardware would
> > be even better, but it is at least a start.
> Absolutely.  Even with our server/cluster room in the building, it is a
> pain to walk down there every time something needs to be bounced (like
> right now:-) and sometimes I work at home (like right now).  WOL won't
> bounce them, at least as far as my experiment went today.  I may have to
> meddle in the BIOS first.

IMHO a terminal server is not too expensive to save you that trouble.

Michael Will
Michael Will, Linux Sales Engineer
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