Re: nfsroot ro

[Bob Edwards <Robert.Edwards@anu.edu.au>]

Jim McQuillan wrote:
> 
> Ken Yap wrote:
> >
> > >May I have nfsroot read-only ?
> > >
> > >var and tmp is on local hd or ramdisk, login do not work, can't open tty
> > >for /dev/tty1
> >
> > The login process is probably trying to chown /dev/tty1, which is on
> > your nfsroot. One way to allow the root fs to be ro would be to put the
> > files that need to be mutable on a ramdisk.
> 
> That's exactly what we have done with LTSP.  We create a ramdisk
> and mount it on /tmp, then we have symbolic links in the /dev directory
> pointing to the device nodes in /tmp.
> 
> Jim McQuillan
> jam@ltsp.org

I used to be a fan of using RAM disks for /tmp (and /var/tmp), but these days
I am much keener on using an initial RAM disk for the whole of /, only
mounting /usr and /home using nfs. I go for a 16MB initial RAM disk with
all of /etc, /dev, etc. on it, but usually not much of /lib (I put the rest
of the libraries into /usr/lib).

This paradigm is fast (everything is always in RAM), secure (not using
NFS for /etc stuff) and really easy to manage. However, you need enough
RAM to hold the RAM disk as well as the kernel and apps. I use the same
initial RAM disk image for forty lab machines and another one for the 96
nodes in our Beowulf. No need for seperate images for each machine.

Cheers,

Bob Edwards.
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