libvirt users - Jul 2011 - NPIV + KVM

Is this possible:

I would like to have a VM use a FC LUN exported to a virtual wwn (using 
NPIV) as its primary disk.

I was thinking there might be a mechanism to say VM, boot using a LUN 
with this vwwn as your primary disk?

Thanks in advance.

-- 
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Eric Ross
HPC Systems Administrator
Argonne National Laboratory
Leadership Computing Facility
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On Fri, Jul 01, 2011 at 04:16:17PM -0500, Eric Ross
wrote:
> Is this possible:
> 
> I would like to have a VM use a FC LUN exported to a virtual wwn
> (using NPIV) as its primary disk.
> 
> I was thinking there might be a mechanism to say VM, boot using a
> LUN with this vwwn as your primary disk?
Hi Eric,

A VM with a primary disk that's a LU accessed through a vHBA works
fine, however, right now the process is fairly manual.  You would need
to create the vHBA as described at:

http://fedoraproject.org/wiki/Features/VirtStorageManagement

When the host discovers the LUs, use /dev/disk/by-id/... when you
assign the LU to the guest.

Migration presents an additional challenge.  If you want to be able to
migrate the guest, the easiest thing to to is to create two WWNs and
expose the LUs for the guest to both of them.  You can then create the
vHBA with one WWN on the source host and with the second WWN on the
destination host.  If you use /dev/disk/by-id/... for the path that
you assign to the guest, the paths should be correct on both systems.
After migration completes, the vHBA on the source host can be
destroyed and used on the destination host for any subsequent
migrations.

Hope that helps,
Dave