Terminal console

Jean-Christophe Ducom jducom at nd.edu
Mon Jul 29 17:42:56 PDT 2002


 All the nodes of our cluster are linked via serial cables so that they
can be reboot remotely by the previous node:
node1->node2->node3->node4->etc... using the 2 serial ports on each node

kernel /vmlinuz ro root=/dev/hda7 console=ttyS0,9600n8r console=tty0

In /etc/inittab I added:
# For console messages
s0:2345:respawn:/sbin/agetty -h  ttyS0 9600 vt102

Besides other changes in /etc/sysconfig/kudzu, /etc/sysconfig/init,
/etc/securetty, /etc/sysctl.conf (for Sysrq)

Everything works just fine. When I changed grub.conf so that  the
/dev/console is linked to /dev/ttyS0 instead of the monitor /dev/tty0
(which of course is never plugged on any nodes) in order to get all the
messages thru the serial line:
kernel /vmlinuz ro root=/dev/hda7 console=tty0 console=ttyS0,9600n8r
Basically every node needs to have the previous node run minicom to
boot. Otherwise it hangs (if node1 is off, node2 won't be able to boot
until node1 is on and listening on the serial line via minicom).
and vice versa to shut down the nodes.
The problem is if al the cluster needs to be shutdown, this will implies
that every nodes will need to be shut down one after one.

Why everything works fine when /dev/tty0 is chosen by the kernel,
everything works? What is the difference between the video card and the
serial port for this processus)
What am I missing so that the kernel links /dev/ttyS0 to /dev/console
w/out any 'listener' on the serial line?


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