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Re: [OpenStack] OpenStack with Xen


Yes, it needs to be a PV VM at the moment.  It needs to know the UUID of the VM that it lives in, which is why it's looking in /sys/hypervisor/uuid.  We could add a flag to OpenStack to let you pass this in, but there's not really any point, because the performance with the PV VM will be far superior to the HVM one anyway.

To convert it, you need to install a Xen kernel (suffix -virtual if you're on Ubuntu), and then switch it to PV mode using the XenServer CLI:

UUID=$(xe vm-list --minimal name-label='Whatever you called it')
xe vm-param-set uuid=$UUID HVM-boot-policy=""
xe vm-param-set uuid=$UUID PV-bootloader=pygrub

Before you reboot, make sure that the grub config has been set up correctly.  It needs to refer to the new kernel, obviously.  Also, the device names are going to change across the reboot - your root disk is going to stop being /dev/sda1 (or whatever) and turn into /dev/xvda1.  (An exception to this is on Ubuntu Maverick, which uses /dev/sdX in the PV kernel too.)  Most modern installations use disk labels rather than device names these days, so you should be OK, but it's worth checking.

Also, there's a bug in some versions of Pygrub such that it will fail to boot if you have a submenu declaration in your grub.cfg.  If that's the case (common on Ubuntu if you have upgraded your kernel at any point) then you'll need to remove the submenu declaration and its matching close-brace.

After that, reboot, and it should come up in PV mode.  If it fails to come up, set HVM-boot-policy back to 'BIOS order' and you can boot back into HVM mode and figure out what went wrong.



From: jeffrey coho [mailto:jeffreycohobupt@xxxxxxxxx]
Sent: 04 January 2012 06:07
To: Ewan Mellor
Cc: openstack@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Openstack] [OpenStack] OpenStack with Xen

   Does the nova-compute DomU need to be a PV guest?
I have it now on a HVM guest,which it is causing the problem
 Errno 2: No such file or directory: '/sys/hypervisor/uuid'.

If so ,what should i do if i still want to use this HVM without reinstalling
everything again on a PV guest?Thanks.


2012/1/4 Ewan Mellor <Ewan.Mellor@xxxxxxxxxxxxx<mailto:Ewan.Mellor@xxxxxxxxxxxxx>>
Is this what you're looking for?




From: openstack-bounces+ewan.mellor=citrix.com@xxxxxxxxxxxxxxxxxxx<mailto:citrix.com@xxxxxxxxxxxxxxxxxxx> [mailto:openstack-bounces+ewan.mellor<mailto:openstack-bounces%2Bewan.mellor>=citrix.com@xxxxxxxxxxxxxxxxxxx<mailto:citrix.com@xxxxxxxxxxxxxxxxxxx>] On Behalf Of Guilherme Birk
Sent: 03 January 2012 09:06
To: Openstack Mail List
Subject: [Openstack] [OpenStack] OpenStack with Xen

I've already have a Nova configuration working with kvm. Now I want to install and configure the Xen enviroment. Anyone can recomend any material or tutorial where I can find how to install, configure and then integrate with OpenStack ?

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Sincerely yours,