Re: [Xen-devel] EL6 initscript feedback.

[Gordan Bobic <gordan@xxxxxxxxxx>]

On 05/21/2013 06:00 PM, Pasi Kärkkäinen wrote:
> On Tue, May 21, 2013 at 01:02:35PM +0100, Stefano Stabellini wrote:
> > On Tue, 21 May 2013, Gordan Bobic wrote:
> > > On Tue, 21 May 2013 21:30:27 +1000, Steven Haigh <netwiz@xxxxxxxxx> wrote:
> > > > On 05/21/2013 09:20 PM, Stefano Stabellini wrote:
> > > > > On Tue, 21 May 2013, Steven Haigh wrote:
> > > > > > Hi all,
> > > > > >
> > > > > > I'm throwing in my initscript here that I've been pushing to autostart
> > > > > > xen
> > > > > > domains on system boot.
> > > > > >
> > > > > > There are at least one issue right now that I'm not 100% sure how to
> > > > > > handle -
> > > > > > and that is domains created by libvirt. These continue to show in an
> > > > > > xm/xl
> > > > > > list output even when they are not paused / running / blocked - causing
> > > > > > my
> > > > > > initscript to think they are still running.
> > > > > >
> > > > > > The ways I can think of detecting this are *very* hacky and I wouldn't
> > > > > > feel
> > > > > > comfortable to including them in widely used packages.
> > > > > >
> > > > > > I'm wondering if people have some spare time that they review the logic
> > > > > > in
> > > > > > this initscript and provide feedback / suggestions / fixes /
> > > > > > improvements that
> > > > > > I can roll into the scripts to enhance them for all.
> > > > > Is it actually a good idea to mix and match different toolstacks on the
> > > > > same host? If somebody intends to use libvirt, surely she would want to
> > > > > use it for everything?
> > > > This is the interesting question... which probably leads into a more
> > > > important question... What is the best practices for config management
> > > > and defining configuration for DomU's?
> > > >
> > > > While I recommend that people use a plain text config file in
> > > > /etc/xen (although really the files can be just about anywhere) and
> > > > then links to various auto-start DomU's in /etc/xen/auto as a general
> > > > rule.
> > > >
> > > > Am I correct in thinking that libvirt only keeps details of domains
> > > > in the xenstore? Is this recommended? Although more a libvirt question
> > > > - can libvirt be configured to use config files in /etc/xen or
> > > > similar?
> > > I think this is largely distribution dependant. In the case of EL/Fedora,
> > > libvirt seems to be the distro's intended way of managing VMs, at least for
> > > their primary supported virtualization method (KVM).
> > >
> > > In the interest of clarity and maintainability I have seen the light
> > > and converted my VMs to simple text files in /etc/xen/ (there seems to be
> > > no documentation on how to edit most of the settings in xenstore). Some
> > > consensus on the best way would be good, though.
> > I think that using simple text files in /etc/xen for VM configs is
> > clearly the right way to go from the Xen POV.
> Earlier libvirt versions, such as the default version in rhel5/centos5,
> creates /etc/xen/<vm> text files upon VM creation. Later libvirt versions 
> changed the model
> to use xend managed domains with libvirt xml configs.
>
> I wonder if that behaviour could be changed with some config option.. would be 
> nice.
>
> Also to convert from libvirt xml to xen text files you can use this:
>
> virsh dumpxml vm_name > /tmp/a
> virsh domxml-to-native xen-xm /tmp/a > /etc/xen/vm_name
>
> Works for me on centos6 Xen (libvirt 0.10.2).
EL6 seems to keep the VM configs in xenstore, not in xml files.

Gordan


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