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(a)redhat.com> wrote:
> From: "Daniel P. Berrange" <berrange(a)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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