[Beowulf] Problem while booting diskless node.

Panagiotis Christopoulos pxrist at gmail.com
Tue May 1 03:34:57 PDT 2007

On Monday 30 April 2007 13:04, Maxime Kinet wrote:
> Hi,
> I'm trying to set up my first cluster with diskless nodes. To achieve
> that, I'm using PXElinux on a server, running Fedora Core 6, and a
> NFS-mounted root partition on the node.
> Everything works perfectly 
> (getting the IP address, loading the kernel and mounting the
> filesytem) until the node has to run some binaries located into /sbin
> during the boot process. Apparently it's unable to execute them
> because they have been compiled with dynamically linked libraries and
> not statically. The /sbin directory of the node is a simple copy of
> the one of the server. 
 I suppose, that you have done something like, creating a /diskless directory 
inside your nfs,tftp,dhcp etc... server, copying files(eg. /usr/* ) from the 
server, inside that /diskless dir with the same hierarchy, and this resulted 
in a structure which would home, your nfs exported, root fs of your nodes. 
I'm not an expert, but because you said about dynamic libraries, I cannot 
understand, why this is a problem, you copied /sbin inside /diskless, but you 
didn't copy /lib or /usr/lib? The problem with dynamic libraries, starts 
because your /diskless does not have these libraries.
> I tried to avoid the problem using the busybox 
> tools, and it worked a bit better but then it couldn't execute bash
> scripts such as rc.sysinit.
Have you created an init in your busybox, to chroot(exec switch_root) inside 
your nfs root fs after mounting it?
> As anybody ever encountered such problems and what should I do to
> solve it? recompile the kernel of the node or of the server? change
> the distribution? Are there any other simpler method to proceed than
> using PXE?
There are two things you can do. As Douglas Eadline said, it starts by 
thinking if you want to reinvent the wheel or not. If you have time, 
machines, if you know that your teachers won't get annoyed  and you can work 
in a university lab, so you will not pay for the power supply yourself:p  
continue with fedora and all these brainstorming things. You will learn linux 
administration and propably you will do amazing things. If you don't have 
time etc. the guys in warewulf, are doing the same job for about 7 years, and 
they provide you all this knowledge they gained, in a simple installation 
  Back in the technical stuff, from your sayings, I think that something is 
wrong with your /diskless dir(if you have one, of course). I cannot 
understand why you want to use busybox. We use busybox when why want an 
initramfs to do specific jobs(such as unlocking  and mounting encrypted 
partitions,yes, I know this is not the best example I could give) before 
chrooting inside our real root fs and exec init as Mark Hahn said or if we 
are running embedded. Also, I don't think that you have to change your 
distribution, and if you don't like PXE, you can see how the guys in LTSP 
boot( I think they use both PXE and "etherboot" and you can make a choice), 
but for me, syslinux is fine!

This was my point of view, I hope I helped and if you want to ask something, 
feel free to send me a mail, or of course, ask again in the list,  

Panagiotis Christopoulos
System Administrator
Technological Institute of Athens
Department of Informatics

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