On Tue, 2012-08-14 at 07:45 +0100, Stefan Hajnoczi wrote:
> On Tue, Aug 14, 2012 at 09:52:55AM +0800, Asias He wrote:
> > On Mon, Aug 13, 2012 at 3:24 PM, Pekka Enberg <penberg@xxxxxxxxxx> wrote:
> > > On Thu, Aug 9, 2012 at 3:51 AM, Asias He <asias.hejun@xxxxxxxxx> wrote:
<SNIP>
> > >> ---
> > >> diff --git a/tools/kvm/include/kvm/disk-image.h b/tools/kvm/include/kvm/disk-image.h
> > >> index 7ae17f8..54e4047 100644
> > >> --- a/tools/kvm/include/kvm/disk-image.h
> > >> +++ b/tools/kvm/include/kvm/disk-image.h
> > >> @@ -41,6 +41,8 @@ struct disk_image_operations {
> > >>
> > >> struct disk_image_params {
> > >> const char *filename;
> > >> + const char *wwpn;
> > >> + const char *tpgt;
> > >
> > > Maybe it's just me but "wwpn" and "tpgt" really could use a comment
> > > explaining what they are...
> >
> > OK. They are terminology from linux target.
> >
> > wwpn == world wide port number
> > tpgt == target port group tag
>
> Target Portal Group Tag
>
> TPGT is iSCSI-specific terminology but other transports like SAS or FCP
> have similar concepts of naming target ports. I think this terminology
> is used by the LIO target regardless of the fabric.
>
> The SCSI Architecture Model standard says the target port name is the
> "name (see 3.1.70) of a SCSI target port that is world wide unique
> within the SCSI transport protocol of the SCSI domain of that SCSI
> target port".
>
The idea of a TargetPortalGroupTag originally came from iSCSI to do
logical partitioning of a single TargetName (IQN or EUI) instance with
different LUN/auth/network portal configurations. For iSCSI fabrics,
the SCSI target WWPN takes the form of a symbolic string as:
$TARGETNAME+t+0x$TPGT
In generic target_core_fabric_configfs.c code, all SCSI target endpoints
are attached to se_portal_group->tpg_group residing individually
at /sys/kernel/config/target/$FABRIC/$FABRIC_WWN/$TPGT/. It's parent
configfs group is at se_wwn->wwn_group, who's higher level parent is the
top level fabric group registered by the fabric driver with TCM.
So the $FABRIC_WWN/$TPGT/[luns,acls] groups hang off this primary
config_group, which means that currently non iSCSI target based fabric
drivers are required to individually enforce TPGT=1 usage in their own
code when mapping SCSI target WWPNs to underlying storage HW WWPNs, or a
fabric using software based WWPNs (as iSCSI does).
Also, from the user level of rtsadmin/targetcli we do hide the notion of
TPGTs for all non iscsi fabrics, however using rtslib directly does
still require following the underlying $FABRIC/$FABRIC_WWN/$TPGT/ object
layout.
--nab
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