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Re: [libvirt] [PATCH] Add APIs for obtaining the unique ID of LVM & SCSI volumes



On Thu, Aug 02, 2012 at 11:32:14PM -0500, Doug Goldstein wrote:
> On Thu, Aug 2, 2012 at 8:09 AM, Daniel P. Berrange <berrange redhat com> wrote:
> > From: "Daniel P. Berrange" <berrange redhat com>
> >
> > Both LVM volumes and SCSI LUNs have a globally unique
> > identifier associated with them. It is useful to be able
> > to query this identifier to then perform disk locking,
> > rather than try to figure out a stable pathname.
> > --
> 
> Would it not be better to call methods from within libdevmapper and
> libblkid than relying on a callout? Its also worth noting that iSCSI
> provides a GUID for the volume as well.

AFAICT, libblkid does not provide a way to get the SCSI WWN/Serial
values. For iSCSI, I'm assuming that the devices just report the
data using the regular kernel SCSI ioctls, so scsi_id should
'just work' already.

That said, I think I might implement the SCSI lookup directly because
I know remember previous discussions about the fact that the scsi_id
command changed its supported command line arguments over time.

I might try libdevmapper, if I can figure out its crazy API

Daniel
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