Subject: Re: best way to mix workstation/server purpose
To: Chris Brookes <cbrookes@gmail.com>
From: Johnny Lam <jlam@pkgsrc.org>
List: port-xen
Date: 03/21/2006 12:34:19
Chris Brookes wrote:
> On 21/03/06, Manuel Bouyer <bouyer@antioche.eu.org> wrote:
> 
>>NFS is the only thing that will work. You can't mount the same block
>>device multiple times; ffs is not designed for that.
> 
> 
> Is there any other option for having a F/S mounted r/w in one dom-u,
> and mounted r/o in another dom-u? Something other than ffs?

No, there isn't.  As I understand it, each domU runs independently of 
every other domU, which means their respective kernels buffer and cache 
blocks on the partition independently.  So, if domU A is writing to a 
partition that is mounted read-only by domU B, then domU B has no way of 
knowing that the partition is being modified by something other than 
itself, and whatever blocks domU B has cached are potentially incorrect.

You really want NFS.

	Cheers,

	-- Johnny Lam <jlam@pkgsrc.org>