[mythtv-users] Questions on PXE booting a frontend

Jim Stichnoth stichnot at gmail.com
Sun Aug 2 01:04:43 UTC 2009


I have a Zotac IONITX frontend that I'm interested in making
completely diskless and PXE booting, and I have a bunch of questions.
Currently it boots off a 4GB USB flash drive.  It is running MythDora
10.21, using the kernel 2.6.27.9-159.fc10.i686.  I have rsync'd the
root file system to the backend machine, and that directory is
NFS-exported.  I understand that I will need to set up dhcp, tftp, and
syslinux (i.e. pxelinux.0) on the server.

1. Should I expect to have to recompile the kernel to allow an NFS
root file system?  What config options should I look for?

2. Can the DHCP service in a home router and a Linux DHCP/PXE server
coexist on the same network?  I would prefer the home router to handle
most DHCP requests and the Linux server to handle just the PXE-related
requests for this frontend, so that e.g. my wife doesn't lose DHCP for
her laptop computer when the Linux server is down.

3. How reliably does NFS work as a root file system, if the NFS server
goes down and up?  I had trouble using NFS to serve up
videos/posters/pictures until I started using autofs.

4. Related to question #1, I tried setting up grub to boot off the
flash drive but NFS-mount the root file system, to see if my kernel
was capable.  It appeared to do lots of things and boot up partially,
until it reported that it couldn't mount /dev/root.  Am I doing
anything overtly wrong, or is it a kernel problem?  I modified the
frontend's /etc/fstab on the NFS server to mount the NFS version of
the root file system.  I modified grub.conf to look like the
following, where the first boot option was already there and the
second one was added:

default=1
timeout=0
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title MythDora (2.6.27.9-159.fc10.i686)
        root (hd0,0)
        kernel /vmlinuz-2.6.27.9-159.fc10.i686 ro
root=UUID=bb5aa553-5a5a-4c2c-8077-b6dcb9749223 rhgb quiet
        initrd /initrd-2.6.27.9-159.fc10.i686.img

title MythDora with NFS root
        root (hd0,0)
        kernel /vmlinuz-2.6.27.9-159.fc10.i686 ro root=/dev/nfs
nfsroot=192.168.0.205:/storage1/frontends/mythfe2/ROOT
        initrd /initrd-2.6.27.9-159.fc10.i686.img

I added this line to /etc/exports on the NFS server:
/storage1/frontends/mythfe2/ROOT
192.168.0.0/255.255.255.0(rw,no_root_squash,sync)
and verified that I could mount it on the frontend.

So you can see that I'm trying to load the kernel and the initrd image
as before from the (hd0,0) partition of the flash drive but then use
the NFS root file system.

Any advice on this?  Thanks,

Jim


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