Xen users - Oct 2009 - problem sharing logical volume across xen domains

I am a newbie to xen and am seeking some assistance in checking if I''m
heading down the right path or not.

I have a network (192.168.x.x) that I want to keep closed and private for
the most part. I need however to get access to some files generated on the
machines in this private network. So I first tried putting two cards in a
machine running centos 5.2 and connecting one to the private newtork and the
other to the public network. This worked somewhat but I was not able to see
this bridging machine in the private network because I could not run 2 samba
instances on this machine ( I need one for the public network). So I setup
xen on a machine with the 2 NIC''s and assigned one card to the host dom
and
the other to the guest dom which was connected to the private network.

This worked ok, but the only issue was the shared disk space. I
couldn''t use
nfs because each machine operates in a different subnet and I don''t
know how
to export a nfs drive across domains. So I created a logical volume on a
disk and mounted this in both domains.

Here comes the question now. This works some times,. but at other times I
copy files from the private machine to the shared volume but i can''t
see
them from the other domain. Also sometimes the guest domain which houses the
private network server hangs during boot up saying that the logical volume
has been assigned and cannot be mounted.

1) Is what I''m doing using logical volumes across domains legal (best
practise, etc)
2) Is there another way for me to achieve what I want (sharing a disk
partition across domains).

John


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On Sat, Oct 17, 2009 at 10:42 PM, John Preston <byhisdeeds@gmail.com>
wrote:
> I have a network (192.168.x.x) that I want to keep closed and private for
> the most part. I need however to get access to some files generated on the
> machines in this private network. So I first tried putting two cards in a
> machine running centos 5.2 and connecting one to the private newtork and
the
> other to the public network. This worked somewhat but I was not able to see
> this bridging machine in the private network because I could not run 2
samba
> instances on this machine ( I need one for the public network).
Really? It worked for me using 1 samba instance and multiple NICs. If
you''re having problems with that you might have better luck asking
samba guys.
> So I setup
> xen on a machine with the 2 NIC''s and assigned one card to the
host dom and
> the other to the guest dom which was connected to the private network.
>
> This worked ok, but the only issue was the shared disk space. I
couldn''t use
> nfs because each machine operates in a different subnet and I
don''t know how
> to export a nfs drive across domains.
That''s easy enough, as long as NAT is not involved. If NAT is involved
the possible solutions would be :
- use 2 NICs for nfs server, one in private, one in public, OR
- put NFS server on public IP address (assuming your private address
can access public address), OR
- learn how to setup nfs NAT properly (involves assigning static ports
for some RPC services)
> So I created a logical volume on a
> disk and mounted this in both domains.
>
> Here comes the question now. This works some times,. but at other times I
> copy files from the private machine to the shared volume but i
can''t see
> them from the other domain. Also sometimes the guest domain which houses
the
> private network server hangs during boot up saying that the logical volume
> has been assigned and cannot be mounted.
That spells trouble. You''re using non-clustered file system (i.e.
ext3, xfs, etc.) right? Most likely your filesystem is corrupted right
now.
>
> 1) Is what I''m doing using logical volumes across domains legal
(best
> practise, etc)
> 2) Is there another way for me to achieve what I want (sharing a disk
> partition across domains).
Depending on what you need, you might have to use cluster file system.
IMHO the easiest way is to setup samba properly.

-- 
Fajar

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