FAI boot with eth1

[Stephan Hermann]

Moins,


On Wed, 15 Sep 2010 18:44:37 +0200 (CEST)
Cristian Ionescu-Idbohrn <cristian.ionescu-idbohrn at axis.com> wrote:

> On Wed, 15 Sep 2010, C. V. wrote:
> 
> > most of my servers have more than one network card. In some cases I
> > have to use eth devices which are not assigned as eth0 by linux.
> > Sadly that does not seem to work out of the box since FAI always
> > tries to use eth0. So, the boot stops when trying to mount nfs-root
> > because eth0 is not able to find it. It is connected to different
> > Network.
> >
> > Is there a way to assign a specific eth device for this or at least
> > to tell FAI that he should look on all eth devices? I did not find
> > anything about this problem.
> 
> Maybe this (or some similar script) can help:

> [... SNIP ...]


> 
> It returns to stdout the name of the 1st found interface with:
> 
> 	Link detected: yes
> 
> or error status code.

But this leads to another problem.

eth0 + eth1 are both connected to a running switch.
Both nics are signalling "Link up", but that doesn't mean that eth0 is
really able to go to the dhcp.

The underlaying HW box behaves differently, it tries every NIC on board
or on a separate card (like HP does on special HW) and one will
actually succeed.

IPCOnfig inside initramfs does it not.

There are three options:

1. You define in /etc/initramfs-tools/initramfs.conf
    	#
	# DEVICE: ...
	#	
	# Specify a specific network interface, like eth0
	# Overridden by optional ip= bootarg
	#

	DEVICE=

   the DHCP capable device

2. You set DEVICE=all to have all devices checked by ipconfig

3. You use IPAPPEND=2 inside your pxelinux.cfg/<filenmae> config 
   and use latest live-boot (src package) from unstable with bug #593284
   fixed (http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=593284)


The implications are:

1. Not on all machines is the specified device the right dhcp capable
deivce
2. DEVICE=all brings ipconfig to crash, when more then one NIC is able
to reach a DHCP server (whysoever)

3. is the only way to really determine the right dhcp device, because
the PXE loader of the bios is giving the pxelinux bootloader the right
pxe boot device, pxelinux will tell that the kernel and with the update
version of live-boot ipconfig knows which device it has to take...

To make Topic 3 to happen, as said, use latest live-boot packages from
unstable, or apply the patch
to /usr/share/initramfs-tools/scripts/live 


For us, it was really the only way to tell the kernel which device is
dhcp capable, especially when you have 4 or 10 NICs in your box, which
are all "link up" ;)


Regards,
\sh