Optimising pxeboot disk size

[Bernard Dugas]

Hi,

I'm working on a project to have many diskless clients PXEbooting on 1 
nfs server.

This works now, but i would like to have a more efficient use of disk 
space on NFS server.

Lot of root directories can be shared and mounted in fstab, after 
booting process : /usr, /home...

In current solution, the minimum root directories i had to keep for 
managing to boot are :
bin libexec sbin boot etc lib

But it appears that only /etc is really specific to each diskless 
clientX, having basically fstab and rc.conf inside.

All other directories could be shared, and specifically /boot which is 
more that 100MO : i would prefer not to duplicate it, as 10 servers 
would mean 1GO for nothing.

Please would anybody help find a way to share all what we can during 
boot process ?

Another way to ask the question is : how can we mount / and then /etc at 
the begining of boot process instead of mounting only / with etc inside ?

I have tried to do links, but no way to make the boot process follow them...

Thanks a lot,
Best regards,