Something like nullfs (FreeBSD) available in linux

01-26-2011, 11:37 AM

Dear list,

I want to build up a NFS share for several host.
The base system is always equal, only some files are different (files in
/etc and /var, maybe more).

The structure should look like:
Base system is on /basesystem

Then I want a directory for every host:
/nfsroot/host1
/nfsroot/host2
..
/nfsroot/hostn

Client 1 will boot via lan and mount the /nfsroot/host1 via NFS.
On the server the mount could look like:
mount -t nullfs /basesystem /nfsroot/host1
mount -t nullfs /basesystem /nfsroot/host2

If the host1 changes now a file the changed file is not stored in
/basesystem but in /nfsroot/host1.
(so you can think about a filesystem in two layers, the ground layer is
/basesystem and readonly, changes will go to /nfsroot/hostn)

If i upgrade the /basesystem all files should be available for all hosts
expect the files the host changed by itself (they are stored in the
nfsroot/hostn directory).

In FreeBSD there is a file system available called nullfs which could be
used for this.

Is there a similar filesystem for Linux available, too?

Thanks,
Matthias

--
"Programming today is a race between software engineers striving to
build bigger and better idiot-proof programs, and the universe trying to
produce bigger and better idiots. So far, the universe is winning." --
Rich Cook

01-26-2011, 02:56 PM

On Wed, Jan 26, 2011 at 01:37:38PM +0100, Matthias Fechner wrote:
> Dear list,
>
> I want to build up a NFS share for several host.
> The base system is always equal, only some files are different
> (files in /etc and /var, maybe more).
>
> The structure should look like:
> Base system is on /basesystem
>
> Then I want a directory for every host:
> /nfsroot/host1
> /nfsroot/host2
> ..
> /nfsroot/hostn
>
> Client 1 will boot via lan and mount the /nfsroot/host1 via NFS.
> On the server the mount could look like:
> mount -t nullfs /basesystem /nfsroot/host1
> mount -t nullfs /basesystem /nfsroot/host2
>
> If the host1 changes now a file the changed file is not stored in
> /basesystem but in /nfsroot/host1.
> (so you can think about a filesystem in two layers, the ground layer
> is /basesystem and readonly, changes will go to /nfsroot/hostn)
>
> If i upgrade the /basesystem all files should be available for all
> hosts expect the files the host changed by itself (they are stored
> in the nfsroot/hostn directory).
>
> In FreeBSD there is a file system available called nullfs which
> could be used for this.
> Is there a similar filesystem for Linux available, too?

Unionfs or aufs should be able to do that.

yoyo

01-26-2011, 08:13 PM

On 26.01.11 16:56, YoYo Siska wrote:

Unionfs or aufs should be able to do that.

thanks a lot, aufs work perfectly.

Thanks,
Matthias

--
"Programming today is a race between software engineers striving to
build bigger and better idiot-proof programs, and the universe trying to
produce bigger and better idiots. So far, the universe is winning." --
Rich Cook

Wed Jan 26 23:30:01 2011
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