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The xentools (which can be more restrictively referred to as the guest agent) are usually independent of the PV drivers.  Most modern linux kernels include PV drivers - see http://wiki.xen.org/wiki/Xen_Linux_PV_on_HVM_drivers, so if you boot them in HVM mode they will negotiate up to use the PV drivers.  This isn't true for Windows and therefore you have to install the drivers on Windows - which are provided packaged with the guest agent too. 

There are many ways to confirm that the guest is using PV drivers - such as running "dmesg | egrep -i 'xen|front'.  This should then show lines such as "Initialising Xen virtual ethernet driver".

If you have any questions, let us know!

Thanks,

Bob

> -----Original Message-----
> From: Bryan Solie [mailto:bsolie at gmail.com] On Behalf Of Bryan Solie
> Sent: 06 August 2013 14:30
> To: Bob Ball
> Cc: openstack at lists.openstack.org; #OpenStack External Email
> Subject: Re: [Openstack] Cinder basic questions
> 
> Thanks Bob.
> 
> I will monkey with the iscsi a little more to understand how the xenserver
> relationship works.  Thanks for the leads.
> 
> But one followup question: So all I need is xentools installed on the guest
> for it to be considered paravirtualized?
> 
> Bryan
> 
> On Aug 6, 2013, at 8:47 AM, Bob Ball <bob.ball at citrix.com> wrote:
> 
> > Hi Bryan,
> >
> > The volumes should appear in the guest under /dev/xvd<num> when they
> are added.
> >
> > As long as the guest has PV drivers it should work - so HVM guests (such as
> Windows or if you have installed Linux as HVM) with PV drivers will also see
> these volumes added (although clearly with Windows they don't show up
> under /dev!)
> >
> > If using iSCSI then the target should appear on the xenserver host as a PBD
> - so "xe pbd-list" should show one up.  The code that creates this is
> https://github.com/openstack/nova/blob/master/nova/virt/xenapi/volume
> _utils.py#L51 - although that's not too obvious because we actually create a
> XenServer SR and allow that to create the iscsi connection.
> >
> > You're right that xensm isn't supported in the current code and the docs
> need to be updated for Havana, but you don't have to use XenAPINFS - that
> SR is primarily for setups using host aggregates where you want to do in-
> pool migration between hosts.
> >
> > Bob
> >
> >> -----Original Message-----
> >> From: Bryan Solie [mailto:bsolie at well.com]
> >> Sent: 06 August 2013 13:17
> >> To: openstack at lists.openstack.org
> >> Subject: [Openstack] Cinder basic questions
> >>
> >> I am running OpenStack grizzly on Ubuntu 12.04 with XenServer.
> >>
> >> I have tried configuring Cinder with a few different backends, but am not
> >> able to get the end-to-end attachment process working.
> >>
> >> I have tried LVM/iscsi driver: The volumes can be created.  I attach them,
> >> and it returns successfully.  There is an iscsi target on the Cinder host.
> There
> >> is no sign that iscsi target is logged in from the instance I have attached it
> to,
> >> and there's no indication from the CLI that it is actually attached to the
> >> instance.
> >>
> >> I have tried it with xensm storage backend, which I found in the Grizzly
> docs.
> >> But this backend no longer seems supported by the code.  Not sure if this
> is
> >> out of sync somehow; I don't know the history.
> >>
> >> I have tried it with XenapiNFS, and again, the volumes seem to be
> created,
> >> and I attach them without error, but they are not obviously visible from
> the
> >> instance.  I can't find an iscsi target when I create the volume in this case;
> I
> >> don't know whether there is supposed to be one with this driver or not.
> >> Code suggests no, but I am a Python newbie.
> >>
> >> The one that seems most successful for me is the LVM/iscsi driver, but
> how
> >> do I get the volume to automatically login to the created iscsi target?
> >>
> >> Is there a requirement to use XenapiNFS if I am on xenserver?  What are
> the
> >> advantages?  And again, how do I get created volumes to be visible from
> >> inside the instance?
> >>
> >> The doc says with xenserver I can attach volumes only to paravirtualized
> >> guests.  I have looked at the PV-bootloader for the instances I have
> created,
> >> and it is blank.  As I understand it, they need to be on pygrub to be
> >> paravirtualized?  Again, I am a little new on this, and I have not been able
> to
> >> get much out of google.
> >>
> >> Any help would be appreciated.
> >>
> >> Bryan
> >> _______________________________________________
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