[Beowulf] Remote console management

Ashley Pittman ashley at quadrics.com
Fri Sep 23 03:19:24 PDT 2005

On Thu, 2005-09-22 at 23:33 -0500, Bruce Allen wrote:
> > IPMI gives you the ability to do a console over IPMI (text only).  I am 
> > not sure how well this works in general.
> The main issue is 'where is the console output buffered'.  Look back at my 
> original posting.  I want to see the same display that someone plugging in 
> a monitor would see.  This means that at least the last 24*80 bytes have 
> to be buffered.  And ideally somewhat more.

The normal way of doing this is to use software to do the buffering,
assume you have a real serial line going into the box and it's spitting
out text in much the same way as a real tty does under linux...  Now
both the serial port and the terminal server are effectively stateless
but think about what happens when you want to connect to it, do you just
telnet to the relevant port on the terminal server?  Or do you use a
deamon running on your head node to route all your serial output via,
this way you can implement full logging, access control (including
options such as 'whos using it?' and 'log them out') and if the software
is any good it will replay you the last N lines of output when you
attach to it.

Unfortunately this only works for raw serial, it doesn't work as well
for graphical access to the bios but then the magic java utility that
almost always need a windows machine and 150% of the bandwidth you
actually have to your machine room does this side of it for you.

Even with both of these rebooting a cluster is a PITA, mainly because
anything graphical has to be repeated for each node.

Unfortunately this whole aspect of clustering isn't great at the minute,
it's getting there slowly but it's still a long way behind Alpha boxes
of five plus years ago where you could simply login to the serial
hardware and type reboot :(

One bizarre side effect of all these java console clients, most of them
are capable of doing a screen dump to file and it's becoming more common
for people to send 10Mb+ tiff images of the console when reporting


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