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.
Server:
=======
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
clients.
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.
/tmp
/var/tmp
/var/run
/var/log
/var/state
/var/account
/var/lock
8. Some directories are remounted to enable nfs v3. It seems
like (my kernel at least) does not support nfs v3 for the
root.
/usr
/lib
/opt
/etc
/root
/bin
/sbin
/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?
Regards,
// Ola
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