CentOS - Feb 2014 - Read only nfsroot and diskless booting CentOS 6?

Does anyone have any good how-to's or documentation on setting up read only
root NFS for pxe booting diskless computers? A few months ago I stumbled upon an
official Redhat doc through a google search(not hosted by redhat and I cannot
find it anywhere on the Redhat site) written by Dave Kline named
"Configuring diskless clients with Red Hat Enterprise Linux" from
2011. It seemed to be a work in progress but the steps in it did work for doing
nfsroot for one diskless client only. It did not have any explanation for doing
read only nfsroot or how to deal with /var for multiple systems. I know there is
a file in /etc/sysconfig/readonly-root but I could not get it working correctly.
I did kludge together something for /var where during the init process I created
a tmpfs for /var and rsync'd a copy of /var from an nfs mount. This worked,
but again I felt it was a kludge to a proper solution.

Although I got this working for booting an old bios based Dell and a VM via PXE
boot, I don't know if it will work for newer UEFI based computers. I'm
just looking to boot about 20 or so small modern PC's into a stripped down
gnome desktop with a few apps installed. I still have not decided on the
diskless clients I want to use. I was thinking either something like the low end
intel NUC or one of the small AMD APU based PC's.

David C Miller.

On Wed, Feb 5, 2014 at 11:47 AM, David C. Miller
<millerdc at fusion.gat.com> wrote:
> Does anyone have any good how-to's or documentation on setting up read
only root NFS for pxe booting diskless computers? A few months ago I stumbled
upon an official Redhat doc through a google search(not hosted by redhat and I
cannot find it anywhere on the Redhat site) written by Dave Kline named
"Configuring diskless clients with Red Hat Enterprise Linux" from
2011. It seemed to be a work in progress but the steps in it did work for doing
nfsroot for one diskless client only. It did not have any explanation for doing
read only nfsroot or how to deal with /var for multiple systems. I know there is
a file in /etc/sysconfig/readonly-root but I could not get it working correctly.
I did kludge together something for /var where during the init process I created
a tmpfs for /var and rsync'd a copy of /var from an nfs mount. This worked,
but again I felt it was a kludge to a proper solution.
>
> Although I got this working for booting an old bios based Dell and a VM via
PXE boot, I don't know if it will work for newer UEFI based computers.
I'm just looking to boot about 20 or so small modern PC's into a
stripped down gnome desktop with a few apps installed. I still have not decided
on the diskless clients I want to use. I was thinking either something like the
low end intel NUC or one of the small AMD APU based PC's.
>
Does drbl (http://drbl.org/) come close enough to what you want?  I
only use it to PXE boot to clonezilla for image copies but the setup
scripts offer the option for running diskless clients too, and the
scripts do all the work for you.   I think there is are options to
build separate root trees for each client or to share one. And it is
packaged for an easy install.   In clonezilla mode it has the option
to use the image from a clonezilla-live iso (that it will download for
you) and I use that to get a current ubuntu kernel with good hardware
support, but in standard linux mode you may have to use the server's
kernel.

-- 
   Les  Mikesell
       lesmikesell at gmail.com