[mythtv-users] Diskless Front End (again)

[Neil Sedger]

Rich West wrote:
> Neil Sedger wrote:
> The only noise it generates is in regard to it being unable to write to
> fstab.
> 
> I guess I will have to dig in to that disklessrc startup script to see
> where it might be failing..

...having upgraded my diskless from FC3 to FC6, I now have the same problem!

A good google around - as the issues are due to RedHat's 
system-config-netboot - didn't help much until I came across the 
diskless page on the mythtv wiki:
http://www.mythtv.org/wiki/index.php/Diskless_Frontend#Creating_the_boot_images
See the bit about issues with system-config-netboot for FC5 and FC6.

Firstly, the initrd does not contain 'mount.nfs' which is kinda useful 
for netboot systems... I suspect you've got past this point though as 
your root and snapshot mount, just read-only...
Secondly, newer kernels will not mount an nfs share rw when another 
share from the same server is already mounted ro.
See http://lkml.org/lkml/2006/10/18/264 for explanation.
I am hoping that the 'mount -o remount,rw /.snapshot &&' bit in the wiki 
addresses this issue, this is where I'm at.

Mine also spouts errors because it cannot write to mtab (not fstab) when 
it tries to mount the snapshot because /etc/mtab is on the ro filesystem 
at that point. I've edited my disklessrc to include switch '-n' to the 
mount command, which skips writing to mtab. Don't know why this 
behaviour is different between FC3 and FC6...
An alternative might be to remove (rename just in case...) /etc/mtab and 
instead symlink it to /proc/mounts. I don't think you can do this with 
fstab, but I don't know why it should be writing to fstab on boot anyway?



Aside from all this, how are you supposed to update a working system? 
You can't use rpm/yum on the diskless box because the root filesystem is 
readonly, and you can't just chroot and run them on the server as this 
does not take account of all the files in the 'snapshot' dir which get 
mounted all over the place.
?


Cheers

Neil