Serial Console

Jozef Skvarcek jozef at
Mon Jul 15 07:11:25 PDT 2002


1. You need 8 serial ports on the console server. I recommend purchasing 
Cyclades TS1000 ( or equivalent. If money is
short, you may simply connect from your head node to a worker node
directly with the null-modem cable. In that case, you will be able to 
work on a single worker node at a time, obviously... Say, you decide
to go without the console server. Connect the COM2(ttyS1) at the head with
the ttyS1 on a worker. Make sure package `minicom', which emulates the
terminal, is installed on the head node. On the head, lunch `minicom'
as root. Configure the minicom to use ttyS1 and match the serial settings
on the worker. Then you should be able to work.

2. You need to configure the worker for the serial connection.
Note, I don't recommend a worker configuration without any video card
since you would not be able to access BIOS on the motherboard, SCSI BIOS
etc. via the serial port (limitation of PC hardware...), just get some
cheap one.

2a. Make sure the COM2(ttyS1) is enabled in BIOS and the settings
(port/IRQ) are correct.
2b. Make sure `mgetty' package is installed, it will listen on the serial
port and will open the login session if it sees activity there.
2c. Create the configuration file for mgetty
`/etc/mgetty+sendfax/mgetty.config'. It should include lines like these:

	port ttyS1
	direct y
	speed 9600
	term vt100

I prefer speed 9600 bps since it is a common value on Cisco, Sun stuff...
2d. Edit file `/etc/securetty'. Add line


so that you will be able to logon as root directly.
2e. Edit file `/etc/inittab'. Add line

	T0:2345:respawn:/sbin/mgetty ttyS0

2f. Optionally, I recommend redirecting the kernel boot messages and the
LILO prompt to the serial port as well. Edit the `/etc/lilo.conf' file.
Add lines:


Run the `lilo' command (I am not sure this is necessary, though).

Restart the worker. You should see the LILO prompt and the boot messages
in the minicom on the head node, then press <ENTER> which should bring the
login prompt up.


On Sat, 13 Jul 2002, Timothy W. Moore wrote:

> This should be in the Redhat docs...and if it is, I have been unable to 
> find it.
> I built an 8-CPU cluster, and because I am not a linux guru, took the 
> lazy route and used a KVM switch.  I upgraded my networking with GigE 
> that now occupies the riser slot...former resting place of my video 
> card.  I now want to upgrade to Redhat 7.3 without the benefit of a 
> video card and have no idea where to begin.  The first question is 
> I need a special card?  switch? The second question is 
> software...what files do I change to redirect the ouput to com2(?)?  If 
> there is an Idiot's guide (step by step) on the net, the URL would be 
> greatly appreciated.  Remember...I know absolutely nothing about this 
> topic.
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