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Re: Floppy and tftp - was Woody Freeze

On Mon, Apr 09, 2001 at 03:07:04PM +0530, Ganesan Rajagopal wrote:
> > I'm working on a project to run debian (servers and clients) diskless.
> > Im actually sitting with a totally diskless computer running debian
> > started with PXE, GRUB, Linux-2.4.2 and nfs-root. I intend to make
> > diskless-server and diskless-client packages to simplify this.
> > Is there anyone else out there that are interested in this?
> I am very interested in this. Do you have a web page describing this? 

To bad I have not. But I'll share some of my experience here.

There are actually some packages in debian that makes diskless
booting easier. See netboot and diskless. I have personally not
used them but all reports about how to do it would be great.

Here is some scetches about how it is set up.

dhcpd (with some BOOTP things to load the kernel with right ip).
tftpd (pointing to /rboot directory)
grub (located in /rboot so that the client can find it, yes it should
      be in an other directory. :) This is a special grub bin to   
      support network booting via PXE.
chroot images (in /images, a complete client installation).
nfs-server (exporting /images)
kernel (located in /images/foo/kernel)

Client: (well the image in /images/foo)
kernel (see above)
devfs (speeds things up)
ramfs (to localize the host, /tmp /var/tmp /var/run etc.)
mount (mounts /usr /root /bin /lib etc to support nfs v3)
mkdirscript (that creates some dirs in /var/log so logging to
             memory works)

So what I want to create is a couple of debian pacakges that:
1. Sets up the server (almost automaticly) to allow diskless
2. Creates client images on the server (if you do not want to run
   the same image as the server)
3. Depend, recommend or suggest bootp, nfs-server and tftp and
   configure them as far as possible.
4. Run a second kernel on the server to make it possible to
   administrate the clients from the server, like apt-get install...
   without problem). This is a later task... :)
5. On the client images, configure them to be a diskless client,
   like add some lines to /etc/fstab, use devfs and create dirs
   in /var/log on boot.

So this is how the computer boots:
1. The boot ROM in the network card is activated and loaded.
   I use a Intel PXE capable card but others may work too.
2. The client asks (via dhcp) for an ip address and some
   information about which server to boot from.
3. It retrieves the boot-loader (GRUB) via tftp from the server.
4. GRUB then loads the kernel (and maybe modules too if needed) as
   you have specified in the special grub-boot script.
   Here you have to give some specific boot options to boot
   over nfs. To let more than one host boot over nfs you also have
   to give some bootp options to the dhcpd server config...
5. The kernel (and maybe modules) is loaded and mounts
   server:/images/foo as its root /.

* Normal startup but some special things:
6. Devfsd is loaded which makes the computer a bit faster because
   it does not have to ask the nfs-server for the devices all
   the time.
7. Some directories are mounted with ramfs.
8. Some directories are remounted to enable nfs v3. It seems
   like (my kernel at least) does not support nfs v3 for the
   /home -> to some other place maybe.
9. Swapd is started to allow swapping over nfs. But there are
   some problems with this and it probably have to do with
   that the filesystem is not local. I do not know... Anyone
   have experience with this?

Well now the host behaves (almost) as any other debian host.

To update the image I log in to the server and
chroot to the image root.

ssh foo
sudo bash
chroot /images/bar

and then
apt-get update
apt-get upgrade

or similar.

Atually I would like to boot another kernel at the server for
updating the image but I have not found any good solution. The
user-space-linux project looks nice but it uses a file as
the filesystem...

Hope this helps. :)

But now I have a question.

What names should these packages have?
Should it be task packages?


// Ola

 --------------------- Ola Lundqvist ---------------------------
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