Goodbye Xen on RH/Fedora?

[Evan Lavelle]

It seems I've been a bit thick. It's been pretty obvious recently that 
Xen isn't flavour of the month around here, but I assumed there were 
good reasons for that. Now, rather belatedly, I've found

http://www.redhat.com/about/news/prarchive/2008/qumranet.html

In short, RedHat paid $107 million for Qumranet in September 2008. The 
acquisition includes KVM.

I've got 2 years invested in Xen, on FC8, and I can't help feeling that 
I've been shafted. Am I alone?

-Evan

[Ján ONDREJ (SAL)]

On Wed, Jan 21, 2009 at 08:15:00AM +0000, Evan Lavelle wrote:
>  It seems I've been a bit thick. It's been pretty obvious
> recently that  
>  Xen isn't flavour of the month around here, but I assumed there were  
>  good reasons for that. Now, rather belatedly, I've found
>
>  http://www.redhat.com/about/news/prarchive/2008/qumranet.html
>
>  In short, RedHat paid $107 million for Qumranet in September 2008. The  
>  acquisition includes KVM.
>
>  I've got 2 years invested in Xen, on FC8, and I can't help feeling that  
>  I've been shafted. Am I alone? 
Not alone, same situation for me.

I am using Xen aprox 2 years too on our university, but with end of F8 there
is not a fully functional Xen Dom0 and also DomU kernel for any stable
Fedora.

KVM is still not a replacement for paravirtualized machines and I think
fully virtualized KVM will be slower like a paravirtualized XEN.
Also I am missing some howtos for migration to KVM/xenner.

			Jan ONDREJ (SAL)

[Richard W.M. Jones]

On Wed, Jan 21, 2009 at 09:20:48AM +0100, Jan ONDREJ (SAL) wrote:
>  KVM is still not a replacement for paravirtualized machines and I
> think
>  fully virtualized KVM will be slower like a paravirtualized XEN. 
KVM is a great replacement for Xen.  It's much easier to use for a
start -- no more rebooting into a completely separate kernel^W
hypervisor.  As long as you have the virtio drivers in the guest,
which is the default for all new Linux distros, performance is roughly
the same.

>  Also I am missing some howtos for migration to KVM/xenner. 
Install a recent Linux kernel in the guest, adjust the configuration
file[1], and reboot.  You only need Xenner if you want to run the Xen
PV guest unchanged (ie. without installing a new guest kernel).

Rich.

[1] 'virsh edit domname', and edit the domain type, <os> and
<emulator> fields, as detailed here: http://libvirt.org/drvqemu.html


-- 
Richard Jones, Emerging Technologies, Red Hat  http://et.redhat.com/~rjones
virt-p2v converts physical machines to virtual machines.  Boot with a
live CD or over the network (PXE) and turn machines into Xen guests.
http://et.redhat.com/~rjones/virt-p2v

[Ján ONDREJ (SAL)]

On Wed, Jan 21, 2009 at 11:50:39AM +0000, Richard W.M. Jones wrote:
>  On Wed, Jan 21, 2009 at 09:20:48AM +0100, Jan ONDREJ (SAL) wrote:
>  > KVM is still not a replacement for paravirtualized machines and I think
>  > fully virtualized KVM will be slower like a paravirtualized XEN.
>  
>  KVM is a great replacement for Xen.  It's much easier to use for a
>  start -- no more rebooting into a completely separate kernel^W
>  hypervisor.  As long as you have the virtio drivers in the guest,
>  which is the default for all new Linux distros, performance is roughly
>  the same.
>  
>  > Also I am missing some howtos for migration to KVM/xenner.
>  
>  Install a recent Linux kernel in the guest, adjust the configuration
>  file[1], and reboot.  You only need Xenner if you want to run the Xen
>  PV guest unchanged (ie. without installing a new guest kernel). 
For F10 there is no need to change domU kernel. It's same.

But after reboot to KVM, my virtual machine has an 8139 network card.
Is it paravirtualized? How I can tell my machine to use "virtio" drivers?

		SAL

[Richard W.M. Jones]

On Wed, Jan 21, 2009 at 01:12:52PM +0100, Jan ONDREJ (SAL) wrote:
>  On Wed, Jan 21, 2009 at 11:50:39AM +0000, Richard W.M. Jones wrote:
>  > On Wed, Jan 21, 2009 at 09:20:48AM +0100, Jan ONDREJ (SAL) wrote:
>  > > KVM is still not a replacement for paravirtualized machines and I think
>  > > fully virtualized KVM will be slower like a paravirtualized XEN.
>  > 
>  > KVM is a great replacement for Xen.  It's much easier to use for a
>  > start -- no more rebooting into a completely separate kernel^W
>  > hypervisor.  As long as you have the virtio drivers in the guest,
>  > which is the default for all new Linux distros, performance is roughly
>  > the same.
>  > 
>  > > Also I am missing some howtos for migration to KVM/xenner.
>  > 
>  > Install a recent Linux kernel in the guest, adjust the configuration
>  > file[1], and reboot.  You only need Xenner if you want to run the Xen
>  > PV guest unchanged (ie. without installing a new guest kernel).
>  
>  For F10 there is no need to change domU kernel. It's same.
>  
>  But after reboot to KVM, my virtual machine has an 8139 network card.
>  Is it paravirtualized? How I can tell my machine to use "virtio" drivers?
You have to tell the host to give the guest a virtio network card -
change the NIC <model type='virtio'/> as described here:

http://libvirt.org/formatdomain.html#elementsNICS

The guest needs to have a relatively up to date kernel which has
drivers for the virtio network card - that's included in all recent
Linux kernels (virtio_net.ko).

Rich.

-- 
Richard Jones, Emerging Technologies, Red Hat  http://et.redhat.com/~rjones
virt-top is 'top' for virtual machines.  Tiny program with many
powerful monitoring features, net stats, disk stats, logging, etc.
http://et.redhat.com/~rjones/virt-top

[Neil Thompson]

On Wed, Jan 21, 2009 at 08:15:00AM +0000, Evan Lavelle wrote:
>  It seems I've been a bit thick. It's been pretty obvious
> recently that  
>  Xen isn't flavour of the month around here, but I assumed there were  
>  good reasons for that. Now, rather belatedly, I've found
>
>  http://www.redhat.com/about/news/prarchive/2008/qumranet.html
>
>  In short, RedHat paid $107 million for Qumranet in September 2008. The  
>  acquisition includes KVM.
>
>  I've got 2 years invested in Xen, on FC8, and I can't help feeling that  
>  I've been shafted. Am I alone?
>  
Xen (paravirt) is in the process of going into the Mainstream kernel, also
RHEL5, which has a number of years left, includes xen - I don't think
Red Hat are going to mess their corporate clients around by removing it.
The problem with F8 is that the kernel people could no longer drag an obsolete
(2.6.21) kernel around just for xen, and decided to concentrate on helping
get it into the mainstream kernel.  This has taken longer than expected.

RHEL (and CentOS) 5.3 has support for Fedora 10 (and above) domUs, and Fedora 11
should have, as well.

Another thing the Red Hat people are working on is to make the management interface
(and the images, I think - please correct me if I'm wrong RH folks) the same for
Qemu,
KVM and xen, so the impact of moving from one to the other is very small.

Shafted?...I don't think so. We're just in a blip at the moment.


-- 
Cheers! (Relax...have a homebrew)

Neil

...aliquando et insanire iucundum est.
                           -- Lucius Annaeus Seneca

[Ján ONDREJ (SAL)]

On Wed, Jan 21, 2009 at 11:44:35AM +0200, Neil Thompson wrote:
>  On Wed, Jan 21, 2009 at 08:15:00AM +0000, Evan Lavelle wrote:
>  RHEL (and CentOS) 5.3 has support for Fedora 10 (and above) domUs, and Fedora 11
>  should have, as well. 
Just there is at least one critical problem with Fedora 10 DomU and also one
for Fedora 9 DomU, so Fedora 10 kernels can't run stable. :(

https://bugzilla.redhat.com/show_bug.cgi?id=478414

                SAL

[Neil Thompson]

On Wed, Jan 21, 2009 at 10:51:07AM +0100, Jan ONDREJ (SAL) wrote:
>  On Wed, Jan 21, 2009 at 11:44:35AM +0200, Neil Thompson wrote:
>  > On Wed, Jan 21, 2009 at 08:15:00AM +0000, Evan Lavelle wrote:
>  > RHEL (and CentOS) 5.3 has support for Fedora 10 (and above) domUs, and Fedora 11
>  > should have, as well.
>  
>  Just there is at least one critical problem with Fedora 10 DomU and also one
>  for Fedora 9 DomU, so Fedora 10 kernels can't run stable. :(
>  
>  https://bugzilla.redhat.com/show_bug.cgi?id=478414
>   
Your problem is with an F8 Dom0...the 2.6.29 kernel that will (hopefully) be in
F11 should sort out most of the paravirt problems, from what I can see.  I'm
not sure what the status of the code in EL5.3 is, maybe the RH people 
can comment.

I don't think your problem qualifies as "shafted".

-- 
Cheers! (Relax...have a homebrew)

Neil

...aliquando et insanire iucundum est.
                           -- Lucius Annaeus Seneca

[Ján ONDREJ (SAL)]

On Wed, Jan 21, 2009 at 12:04:34PM +0200, Neil Thompson wrote:
>  On Wed, Jan 21, 2009 at 10:51:07AM +0100, Jan ONDREJ (SAL) wrote:
>  > On Wed, Jan 21, 2009 at 11:44:35AM +0200, Neil Thompson wrote:
>  > > On Wed, Jan 21, 2009 at 08:15:00AM +0000, Evan Lavelle wrote:
>  > > RHEL (and CentOS) 5.3 has support for Fedora 10 (and above) domUs, and Fedora
> 11
>  > > should have, as well.
>  > 
>  > Just there is at least one critical problem with Fedora 10 DomU and also one
>  > for Fedora 9 DomU, so Fedora 10 kernels can't run stable. :(
>  > 
>  > https://bugzilla.redhat.com/show_bug.cgi?id=478414
>  > 
>  
>  Your problem is with an F8 Dom0... 
Not exactly. On my F8 Dom0 Fedora 10 works well with latest fc8 domU kernel.
Just when trying to boot and run .fc10. PAE or x86_64 kernel, it fails
in less than 48 hours.

>  the 2.6.29 kernel that will (hopefully) be in
>  F11 should sort out most of the paravirt problems, from what I can see.  I'm
>  not sure what the status of the code in EL5.3 is, maybe the RH people 
>  can comment. 
I think it will not be in 2.6.29. Although
http://wiki.xensource.com/xenwiki/XenParavirtOps says thatit's planned for
2.6.29, I can't see any progres in 2.6.29-rc2 changelog:
http://www.kernel.org/pub/linux/kernel/v2.6/testing/ChangeLog-2.6.29-rc2
http://www.kernel.org/pub/linux/kernel/v2.6/testing/ChangeLog-2.6.29-rc1

I think, 2.6.29 is closed for large changes. Or I missed something?

			SAL

[Veli-Pekka Kestilä]

Jan ONDREJ (SAL) wrote:
>  On Wed, Jan 21, 2009 at 12:04:34PM +0200, Neil Thompson wrote:
>    
> > On Wed, Jan 21, 2009 at 10:51:07AM +0100, Jan ONDREJ (SAL) wrote:
> >     
> >> On Wed, Jan 21, 2009 at 11:44:35AM +0200, Neil Thompson wrote:
> >>       
> >>> On Wed, Jan 21, 2009 at 08:15:00AM +0000, Evan Lavelle wrote:
> >>> RHEL (and CentOS) 5.3 has support for Fedora 10 (and above) domUs, and Fedora
> 11
> >>> should have, as well.
> >>>         
> >> Just there is at least one critical problem with Fedora 10 DomU and also one
> >> for Fedora 9 DomU, so Fedora 10 kernels can't run stable. :(
> >>
> >> https://bugzilla.redhat.com/show_bug.cgi?id=478414
> >>
> >>       
> > Your problem is with an F8 Dom0...
> >     
>
>  Not exactly. On my F8 Dom0 Fedora 10 works well with latest fc8 domU kernel.
>  Just when trying to boot and run .fc10. PAE or x86_64 kernel, it fails
>  in less than 48 hours.
>
>     
I would really recommend you to change the Dom0 to be CentOS 5.2 or 
newer, Fedora 8 has been "Dead" about ½-month allready and will not get 
any updates be it KVM, QEMU or Xen. So the bugs will not be fixed and 
there will be no security updates for F8. I have some virtual 
environments running still vith Xen and F7 or F8, but will migrate them 
soon to CentOS for stability and long term support and I quite much 
expect them to be still supported 5-years from now.

Also I don't think kvm will be that different or hard to learn if it 
becomes to that. It actually has paravirtual network drivers for windows 
from Qumranet which you can get without extra fee so I think if you are 
having windows clients it could be way to go in future. For xen you need 
to pay to Novell for that priviledge.

So all in all I think for me this aquisition is good news. I think most 
problems with xen comes from xensource as it's they only product 
generating income and for that reason the opensource version seems to 
get less care than the version you can buy from them. (This is just my 
opinion so it's not necessarily so)

Greetings,
Veli-Pekka

[Pasi Kärkkäinen]

On Wed, Jan 21, 2009 at 01:40:55PM +0200, Veli-Pekka Kestilä wrote:
>  Jan ONDREJ (SAL) wrote:
>  >On Wed, Jan 21, 2009 at 12:04:34PM +0200, Neil Thompson wrote:
>  >  
>  >>On Wed, Jan 21, 2009 at 10:51:07AM +0100, Jan ONDREJ (SAL) wrote:
>  >>    
>  >>>On Wed, Jan 21, 2009 at 11:44:35AM +0200, Neil Thompson wrote:
>  >>>      
>  >>>>On Wed, Jan 21, 2009 at 08:15:00AM +0000, Evan Lavelle wrote:
>  >>>>RHEL (and CentOS) 5.3 has support for Fedora 10 (and above) domUs, and 
>  >>>>Fedora 11
>  >>>>should have, as well.
>  >>>>        
>  >>>Just there is at least one critical problem with Fedora 10 DomU and also 
>  >>>one
>  >>>for Fedora 9 DomU, so Fedora 10 kernels can't run stable. :(
>  >>>
>  >>>https://bugzilla.redhat.com/show_bug.cgi?id=478414
>  >>>
>  >>>      
>  >>Your problem is with an F8 Dom0...
>  >>    
>  >
>  >Not exactly. On my F8 Dom0 Fedora 10 works well with latest fc8 domU 
>  >kernel.
>  >Just when trying to boot and run .fc10. PAE or x86_64 kernel, it fails
>  >in less than 48 hours.
>  >
>  >  
>  I would really recommend you to change the Dom0 to be CentOS 5.2 or 
>  newer, Fedora 8 has been "Dead" about ½-month allready and will not get 
>  any updates be it KVM, QEMU or Xen. So the bugs will not be fixed and 
>  there will be no security updates for F8. I have some virtual 
>  environments running still vith Xen and F7 or F8, but will migrate them 
>  soon to CentOS for stability and long term support and I quite much 
>  expect them to be still supported 5-years from now.
>  
>  Also I don't think kvm will be that different or hard to learn if it 
>  becomes to that. It actually has paravirtual network drivers for windows 
>  from Qumranet which you can get without extra fee so I think if you are 
>  having windows clients it could be way to go in future. For xen you need 
>  to pay to Novell for that priviledge.
>   
You can always use "GPLPV" Windows drivers for Xen. They're open source.

>  So all in all I think for me this aquisition is good news. I think
> most 
>  problems with xen comes from xensource as it's they only product 
>  generating income and for that reason the opensource version seems to 
>  get less care than the version you can buy from them. (This is just my 
>  opinion so it's not necessarily so)
>   
I think Xensource is putting a lot of effort into opensource Xen.

It's just the dom0/pv_ops mess that's causing problems atm.. that _should_
get fixed in the near future.

-- Pasi

[Veli-Pekka Kestilä]

Pasi Kärkkäinen wrote:
>  On Wed, Jan 21, 2009 at 01:40:55PM +0200, Veli-Pekka Kestilä wrote:
>    
> >
> > Also I don't think kvm will be that different or hard to learn if it 
> > becomes to that. It actually has paravirtual network drivers for windows 
> > from Qumranet which you can get without extra fee so I think if you are 
> > having windows clients it could be way to go in future. For xen you need 
> > to pay to Novell for that priviledge.
> >
> >     
>
>  You can always use "GPLPV" Windows drivers for Xen. They're open source.
>
>     
Thanks for the tip, I have quite many Windows hosts running with Xen and 
have been looking for drivers, but haven't found these. Have to test 
them out when I get my new testing machine.
> > So all in all I think for me this aquisition is good news. I
> think most 
> > problems with xen comes from xensource as it's they only product 
> > generating income and for that reason the opensource version seems to 
> > get less care than the version you can buy from them. (This is just my 
> > opinion so it's not necessarily so)
> >     
>
>  I think Xensource is putting a lot of effort into opensource Xen.
>
>  It's just the dom0/pv_ops mess that's causing problems atm.. that _should_
>  get fixed in the near future.
>
>     
I have noticed that. But main reason for my feeling is that they should 
have started the push much more early than they did. Or maybe it wasn't 
feasible before. Anyway it's just have been my feeling of the whole 
thing and I think it's good to have two competing techs as it will 
provide that both will advance.

Veli-Pekka

[Pasi Kärkkäinen]

On Wed, Jan 21, 2009 at 02:20:19PM +0200, Veli-Pekka Kestilä wrote:
>  >>So all in all I think for me this aquisition is good news. I
> think most 
>  >>problems with xen comes from xensource as it's they only product 
>  >>generating income and for that reason the opensource version seems to 
>  >>get less care than the version you can buy from them. (This is just my 
>  >>opinion so it's not necessarily so)
>  >>    
>  >
>  >I think Xensource is putting a lot of effort into opensource Xen.
>  >
>  >It's just the dom0/pv_ops mess that's causing problems atm.. that _should_
>  >get fixed in the near future.
>  >
>  >  
>  I have noticed that. But main reason for my feeling is that they should 
>  have started the push much more early than they did. Or maybe it wasn't 
>  feasible before. Anyway it's just have been my feeling of the whole 
>  thing and I think it's good to have two competing techs as it will 
>  provide that both will advance.
>   
Yeah well.. IIRC Xen patches were first sent for 2.6.15 kernel. 
Those were rejected and not integrated into vanilla kernel. I can't remember
the reason for that.   

Next attempt failed when others wanted to have the paravirt ops (pv_ops) framework
instead, which enables Linux kernel PV support for any hypervisor, not just for Xen.

Then it took a while to get the generic pv_ops framework done and merged into Linux
kernel. 

And after that it has taken a lot of time to port the Xen domU from the original
"Xenlinux" 
to pv_ops framework. pv_ops Xen domU support has been in mainline Linux kernel since
2.6.23.

And now there is active development going on to get the pv_ops dom0 working
and merged into Linux. Btw Redhat started this work earlier, and it is now
being continued by Xensource (Jeremy Fitzhardinge).

http://wiki.xensource.com/xenwiki/XenParavirtOps

-- Pasi

[Jos Vos]

On Wed, Jan 21, 2009 at 01:53:19PM +0200, Pasi Kärkkäinen wrote:

>  I think Xensource is putting a lot of effort into opensource Xen.
I've heard totally different stories from others.  For almost every
problem you report, they'll tell you that "it is fixed in the
commercial version".

Unfortunately, many companies just "use" open source as marketing
instrument, sometimes they even *abuse* the term (i.e. call software
with no OSI-compliant license open source -- which is not the case
with Xen b.t.w.).

-- 
--    Jos Vos <jos(a)xos.nl&gt;
--    X/OS Experts in Open Systems BV   |   Phone: [phone]
--    Amsterdam, The Netherlands        |     Fax: [phone]

[Ian Jackson]

Jos Vos writes ("Re: [Fedora-xen] Goodbye Xen on RH/Fedora?"):
>  On Wed, Jan 21, 2009 at 01:53:19PM +0200, Pasi Kärkkäinen wrote:
>  > I think Xensource is putting a lot of effort into opensource Xen.
>  
>  I've heard totally different stories from others.  For almost every
>  problem you report, they'll tell you that "it is fixed in the
>  commercial version". 
I don't know where you're asking.  As far as I know Citrix (who bought
Xensource) don't offer paid end-user support as a service for the
upstream version of Xen.  On the other hand they do pay the salaries
of various people who work on it (including me and of course Keir).

If you find bugs in upstream Xen we're certainly interested; we spend
most of our time trying to keep the quality up and manage the incoming
patchstream.  It's true that lists like xen-users aren't that
well-read by developers like me but I think you'll find that's often
true with a Free Software project; many developers prefer to try to
help improve the code than to help individual users one at a time.

As you can see at least some of us do read this list.  I keep an eye
on things here as well as on other distro lists - despite my Debian
background :-) - to see if there's anything we can do to improve
things.  Most of the issues reported here are about Fedora-specific
packaging of course, which I'm no expert on.

It's true that the situation with the kernel is very disappointing.
I don't think I can really explain what I see as the causes.  It's too
much of a political hot potato and I don't want to offend anyone,
particularly my hosts here.

Fortunately we now have Jeremy Fitzhardinge in charge of getting Xen
support into Linux upstream and that seems to be making reasonable
progress - although of course we would all prefer it to be faster.

Regards,
Ian.

NB this is not the official position of Citrix about anything,
just my personal opinion.

[Evan Lavelle]

Veli-Pekka Kestilä wrote:

>  Also I don't think kvm will be that different or hard to learn if
> it 
>  becomes to that. It actually has paravirtual network drivers for windows 
>  from Qumranet which you can get without extra fee so I think if you are 
>  having windows clients it could be way to go in future. For xen you need 
>  to pay to Novell for that priviledge. 
Has anyone tried the Qumranet drivers? My XP clients on Xen are very 
slow. There are free Windows drivers at 
http://wiki.xensource.com/xenwiki/XenWindowsGplPv, but I think they 
still need some development.

-Evan

[Emre Erenoglu]

On Wed, Jan 21, 2009 at 1:00 PM, Evan Lavelle
<[e-mail]&lt;sa212%2Bfcxen(a)cyconix.com&gt;
>  wrote: 
>  Veli-Pekka Kestilä wrote:
>
>   Also I don't think kvm will be that different or hard to learn if it
> > becomes to that. It actually has paravirtual network drivers for windows
> > from Qumranet which you can get without extra fee so I think if you are
> > having windows clients it could be way to go in future. For xen you need to
> > pay to Novell for that priviledge.
> >
>
>  Has anyone tried the Qumranet drivers? My XP clients on Xen are very slow.
>  There are free Windows drivers at
>  http://wiki.xensource.com/xenwiki/XenWindowsGplPv, but I think they still
>  need some development.
>  
I tried, they were running OK for me.
-- 
Emre

[Dustin Henning]

	I tried the Qumranet drivers before I went with Xen.  I don't think
there is necessarily a problem with the Qumranet drivers, in fact, they
could potentially have better inbound speeds than the GPLPV ones (though it
seems unlikely as much as people test and James works on them on the
xen-users list).  The reason the Qumranet drivers don't cut it is because
they are only network drivers.  This means your data access (and possibly
other stuff GPLPV hits) is still fully virtualized.  Another reason I went
with Xen is the PHY: option.  I use a physical data source, as opposed to a
file, for my guests.  Each one has its own HD, actually, though partitions
or RAID arrays would obviously work as well.  If I remember correctly, when
I tried this (some time ago), KVM had no such option.
	Dustin

-----Original Message-----
From: fedora-xen-bounces(a)redhat.com [mailto:[e-mail]]
On Behalf Of Evan Lavelle
Sent: Wednesday, January 21, 2009 07:01
To: fedora-xen(a)redhat.com
Subject: Re: [Fedora-xen] Goodbye Xen on RH/Fedora?

Veli-Pekka Kestilä wrote:

>  Also I don't think kvm will be that different or hard to learn if
> it 
>  becomes to that. It actually has paravirtual network drivers for windows 
>  from Qumranet which you can get without extra fee so I think if you are 
>  having windows clients it could be way to go in future. For xen you need 
>  to pay to Novell for that priviledge. 
Has anyone tried the Qumranet drivers? My XP clients on Xen are very 
slow. There are free Windows drivers at 
http://wiki.xensource.com/xenwiki/XenWindowsGplPv, but I think they 
still need some development.

-Evan

--
Fedora-xen mailing list
Fedora-xen(a)redhat.com
https://www.redhat.com/mailman/listinfo/fedora-xen

[Dustin Henning]

	Also, while I'm on the topic, PCI-passthrough was a factor in my
decision as well.  Unfortunately, I'm stuck on F8 as well, because I can't
get networking to work on CentOS Xen with my hardware.  However, I
understand what is going on, so I'm just holding my breath.
	Dustin

-----Original Message-----
From: fedora-xen-bounces(a)redhat.com [mailto:[e-mail]]
On Behalf Of Dustin Henning
Sent: Wednesday, January 21, 2009 13:35
To: 'Evan Lavelle'; fedora-xen(a)redhat.com
Subject: RE: [Fedora-xen] Goodbye Xen on RH/Fedora?

	I tried the Qumranet drivers before I went with Xen.  I don't think
there is necessarily a problem with the Qumranet drivers, in fact, they
could potentially have better inbound speeds than the GPLPV ones (though it
seems unlikely as much as people test and James works on them on the
xen-users list).  The reason the Qumranet drivers don't cut it is because
they are only network drivers.  This means your data access (and possibly
other stuff GPLPV hits) is still fully virtualized.  Another reason I went
with Xen is the PHY: option.  I use a physical data source, as opposed to a
file, for my guests.  Each one has its own HD, actually, though partitions
or RAID arrays would obviously work as well.  If I remember correctly, when
I tried this (some time ago), KVM had no such option.
	Dustin

-----Original Message-----
From: fedora-xen-bounces(a)redhat.com [mailto:[e-mail]]
On Behalf Of Evan Lavelle
Sent: Wednesday, January 21, 2009 07:01
To: fedora-xen(a)redhat.com
Subject: Re: [Fedora-xen] Goodbye Xen on RH/Fedora?

Veli-Pekka Kestilä wrote:

>  Also I don't think kvm will be that different or hard to learn if
> it 
>  becomes to that. It actually has paravirtual network drivers for windows 
>  from Qumranet which you can get without extra fee so I think if you are 
>  having windows clients it could be way to go in future. For xen you need 
>  to pay to Novell for that priviledge. 
Has anyone tried the Qumranet drivers? My XP clients on Xen are very 
slow. There are free Windows drivers at 
http://wiki.xensource.com/xenwiki/XenWindowsGplPv, but I think they 
still need some development.

-Evan

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[Avi Kivity]

Dustin Henning wrote:
>  	I tried the Qumranet drivers before I went with Xen.  I don't
> think
>  there is necessarily a problem with the Qumranet drivers, in fact, they
>  could potentially have better inbound speeds than the GPLPV ones (though it
>  seems unlikely as much as people test and James works on them on the
>  xen-users list).  The reason the Qumranet drivers don't cut it is because
>  they are only network drivers.  This means your data access (and possibly
>  other stuff GPLPV hits) is still fully virtualized.  
Storage drivers are in the works, hopefully out soon.

>   Another reason I went
>  with Xen is the PHY: option.  I use a physical data source, as opposed to a
>  file, for my guests.  Each one has its own HD, actually, though partitions
>  or RAID arrays would obviously work as well.  If I remember correctly, when
>  I tried this (some time ago), KVM had no such option 
kvm has had this from day 1; 'qemu /dev/volgroup/logvol' will start a 
guest from the specified logical volume.  For good performance I 
recommend 'qemu -drive file=/dev/volgroup/logvol,cache=off'.

Of course, libvirt will handle all that for you.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

[Dustin Henning]

Wow, maybe the F8 documentation doesn't cover that, or maybe I'm remembering
wrong, but good to know for future testing.  Thanks.

-----Original Message-----
From: Avi Kivity [mailto:[e-mail]] 
Sent: Wednesday, January 21, 2009 13:43
To: Dustin.Henning(a)prd-inc.com
Cc: 'Evan Lavelle'; fedora-xen(a)redhat.com
Subject: Re: [Fedora-xen] Goodbye Xen on RH/Fedora?

Dustin Henning wrote:
>  	I tried the Qumranet drivers before I went with Xen.  I don't
> think
>  there is necessarily a problem with the Qumranet drivers, in fact, they
>  could potentially have better inbound speeds than the GPLPV ones (though 
it
>  seems unlikely as much as people test and James works on them on the
>  xen-users list).  The reason the Qumranet drivers don't cut it is because
>  they are only network drivers.  This means your data access (and possibly
>  other stuff GPLPV hits) is still fully virtualized.  
Storage drivers are in the works, hopefully out soon.

>   Another reason I went
>  with Xen is the PHY: option.  I use a physical data source, as opposed to 
a
>  file, for my guests.  Each one has its own HD, actually, though
> partitions
>  or RAID arrays would obviously work as well.  If I remember correctly, 
when
>  I tried this (some time ago), KVM had no such option 
kvm has had this from day 1; 'qemu /dev/volgroup/logvol' will start a 
guest from the specified logical volume.  For good performance I 
recommend 'qemu -drive file=/dev/volgroup/logvol,cache=off'.

Of course, libvirt will handle all that for you.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

[Ján ONDREJ (SAL)]

On Wed, Jan 21, 2009 at 01:40:55PM +0200, Veli-Pekka Kestilä wrote:
>  I would really recommend you to change the Dom0 to be CentOS 5.2 or 
>
>  newer, Fedora 8 has been "Dead" about ½-month allready and will not get  
It's not easy to convert my Dom0 to CentOS, but may be it will be only one
whing which I can do.

But I am still not sure, if it helps. My fc8 domU works well.
May be there are some API changes between fc8 xen dom0 and fc10 domU,
which causes my problems.

>  So all in all I think for me this aquisition is good news. I think
> most  
>  problems with xen comes from xensource as it's they only product  
>  generating income and for that reason the opensource version seems to  
>  get less care than the version you can buy from them. (This is just my  
>  opinion so it's not necessarily so) 
Destination of KVM looks good, but it's still not ready to replace Xen.
May be after 1-2 years of testing it will be better like xen.

			SAL

[Gerd Hoffmann]

>  I think it will not be in 2.6.29. Although
>  http://wiki.xensource.com/xenwiki/XenParavirtOps says thatit's planned for
>  2.6.29, I can't see any progres in 2.6.29-rc2 changelog:
>  http://www.kernel.org/pub/linux/kernel/v2.6/testing/ChangeLog-2.6.29-rc2
>  http://www.kernel.org/pub/linux/kernel/v2.6/testing/ChangeLog-2.6.29-rc1
>  
>  I think, 2.6.29 is closed for large changes. Or I missed something? 
Yea, looks like most of the dom0 stuff missed the boat.  Some prelimary
stuff might be in though (swiotlb patches ran over lkml at least, didn't
check whenever they are actually made it).

You can combine a self-compiled pv_ops/dom0 kernel with the Rawhide xen
packages and help testing/debugging/get-stuff-upstream this way.  You
should follow xen-devel for the latest news & patches if you do so.

The pv_ops/dom0 kernel has some not-yet debugged storage issues (disk
controller either fails after a while or doesn't work at all), which is
the major stumbling block right now.  If you are lucky and the box stays
up long enougth you can start guests.

cheers,
  Gerd

[M A Young]

On Wed, 21 Jan 2009, Jan ONDREJ (SAL) wrote:

>  On Wed, Jan 21, 2009 at 11:44:35AM +0200, Neil Thompson wrote:
> > On Wed, Jan 21, 2009 at 08:15:00AM +0000, Evan Lavelle wrote:
> > RHEL (and CentOS) 5.3 has support for Fedora 10 (and above) domUs, and Fedora 11
> > should have, as well.
>
>  Just there is at least one critical problem with Fedora 10 DomU and also one
>  for Fedora 9 DomU, so Fedora 10 kernels can't run stable. :(
>
>  https://bugzilla.redhat.com/show_bug.cgi?id=478414 
That might actually be nothing to do with xen. Dovecot provides a very 
successful way of hammering the file locking code, and you might just be 
exposing bugs or race conditions in the underlying kernel rather than the 
xen specific code. I suggest you check to see if the processes involved 
are waiting to access locked files.

 	Michael Young

[Ján ONDREJ (SAL)]

On Wed, Jan 21, 2009 at 11:47:55AM +0000, M A Young wrote:
>  On Wed, 21 Jan 2009, Jan ONDREJ (SAL) wrote:
>
> > On Wed, Jan 21, 2009 at 11:44:35AM +0200, Neil Thompson wrote:
> >> On Wed, Jan 21, 2009 at 08:15:00AM +0000, Evan Lavelle wrote:
> >> RHEL (and CentOS) 5.3 has support for Fedora 10 (and above) domUs, and Fedora 11
> >> should have, as well.
> >
> > Just there is at least one critical problem with Fedora 10 DomU and also one
> > for Fedora 9 DomU, so Fedora 10 kernels can't run stable. :(
> >
> > https://bugzilla.redhat.com/show_bug.cgi?id=478414
>
>  That might actually be nothing to do with xen. Dovecot provides a very  
>  successful way of hammering the file locking code, and you might just be  
>  exposing bugs or race conditions in the underlying kernel rather than the 
>  xen specific code. I suggest you check to see if the processes involved  
>  are waiting to access locked files. 
I know, why dovecot fails. And it's not only dovecot, also mysql, apache,
... This bug describes only one example, when I was able to make some logs.

My problem is, that command "sync" and may be similar kernel function called
from dovecot, mysql, ... stays in "D" state. File cache is not stored on my
media. I can read all changed data back from cache, but they are not stored
on disks. After reboot all data written to cache is lost.

May be my english is not perfect, I am sorry. :(

			SAL

[Evan Lavelle]

Neil Thompson wrote:

>  Xen (paravirt) is in the process of going into the Mainstream kernel,
> also
>  RHEL5, which has a number of years left, includes xen - I don't think
>  Red Hat are going to mess their corporate clients around by removing it. 
I hope you're right, but that $107 million is saying something else.

-Evan

[Jeroen van Meeuwen]

Evan Lavelle wrote:
>  Neil Thompson wrote:
>  
> > Xen (paravirt) is in the process of going into the Mainstream kernel, 
> > also
> > RHEL5, which has a number of years left, includes xen - I don't think
> > Red Hat are going to mess their corporate clients around by removing it.
>  
>  I hope you're right, but that $107 million is saying something else.
>   
And http://www.redhat.com/promo/qumranet/ again says Neil's right.

Kind regards,

Jeroen van Meeuwen
-kanarip

[Daniel P. Berrange]

On Wed, Jan 21, 2009 at 08:15:00AM +0000, Evan Lavelle wrote:
>  It seems I've been a bit thick. It's been pretty obvious
> recently that 
>  Xen isn't flavour of the month around here, but I assumed there were 
>  good reasons for that. Now, rather belatedly, I've found
>  
>  http://www.redhat.com/about/news/prarchive/2008/qumranet.html
>  
>  In short, RedHat paid $107 million for Qumranet in September 2008. The 
>  acquisition includes KVM.
>  
>  I've got 2 years invested in Xen, on FC8, and I can't help feeling that 
>  I've been shafted. Am I alone? 
The acqusition of Qumranet has had absolutely *zero* impact on the 
availability Xen kernels in Fedora. The sole reason for not having Xen
support in Fedora 9/10 is that the Dom0 kernel is not yet merged upstream,
and this problem existed long long before Qumranet joined Red Hat.

When we first shipped Xen in Fedora Core 5 (or was it 4?) none of the Xen
code was merged into the mainline Linux kernel tree. For several releases
we spent a great deal of time forward porting Xen to newer kernels. When
we got to Fedora 9 the guest side was merged into the main kernel, but
the host side was not. Unfortunately the Xen host kernel was still on
2.6.18 while Fedora was on 2.6.24 and the kernel was just too old to work
with the userspace tools. We did not want to drop Xen Dom0 host from 
Fedora 9, but we had no viable options to continue with it in the short
term.

Since that time though, Jeremy Fitzhardinge has done alot of work on 
getting Dom0 patches in shape for merging in upstream Linux. It it still
hard to say just when these will be accepted upstream, but there is a
semi-reasonable we'll be able to turn Xen Dom0 back on in Fedora 11
kernels. 

While we (Red Hat) think KVM is a very compelling technology, as long as
Xen is open source, actively maintained upstream & in mainline Linux 
kernels, there's no reason why it shouldn't be available in Fedora. So 
once the Dom0 kernel is merged, Fedora users will be able to have a choice
between Xen and KVM for many future releases. We have also put effort into 
developing Xenner which  allows paravirt Xen guests to be run under KVM
without having to re-configure the guest kernel, giving people a potential
migration strategy if they need one. 

As for RHEL-5, that continues to support Xen, and will do for the entire
of its 7 year lifetime. If you don't want official Red Hat support, there
is also the option of using CentOS 5 as a Xen host which again will have
Xen support it in for whole of its 7 year lifetime. 

So while it is definitely unfortunate that we don't have a Xen Dom0 kernel
in Fedora 9/10, we are *not* trying to shaft anyone & will re-introduce
Xen Dom0 kernels to Fedora when they become available.

Regards,
Daniel
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