CentOS virt - Jan 2015 - CentOS 6 Xen 4.4.1 packages available on virt6-testing / libvirt blktap2 problems

At long last, I've got some beta CentOS 6 4.4.1 packages up on the CBS.

Major updates include:
* Update to Xen 4.4.1. Also includes all XSAs through 114
* Update to latest blktap 2.5
* Updated libvirt packages (1.2.10), which work well with libxl

To use, add the following to a file in /etc/yum.repos.d:

[virt-testing]
name=CentOS-$releasever - virt-testing
baseurl=http://cbs.centos.org/repos/virt6-testing/$basearch/os/
gpgcheck=0
enabled=1

Notes:
* git repo with all the changes to xen can be found here:
 https://github.com/gwd/sig-virt-xen out/virt6/update-4.4.1-4

* The signing infrastructure is not in place, so the binaries are not signed.

* xend is now disabled by default.  You can enable it by running
chkconfig.  xend has been removed from the tree entirely in Xen 4.5,
so this should (hopefully) serve as a "wake-up-call" for people to
begin the transition over to xend.

* A lot have things have changed -- please to test this so we can get
a good idea what may have broken.

 -George

On Mon, Dec 15, 2014 at 06:24:36PM +0000, George Dunlap
wrote:
> At long last, I've got some beta CentOS 6 4.4.1 packages up on the CBS.
> 
Great!
> Major updates include:
> * Update to Xen 4.4.1. Also includes all XSAs through 114
> * Update to latest blktap 2.5
> * Updated libvirt packages (1.2.10), which work well with libxl
> 
> To use, add the following to a file in /etc/yum.repos.d:
> 
> [virt-testing]
> name=CentOS-$releasever - virt-testing
> baseurl=http://cbs.centos.org/repos/virt6-testing/$basearch/os/
> gpgcheck=0
> enabled=1
> 
> Notes:
> * git repo with all the changes to xen can be found here:
>  https://github.com/gwd/sig-virt-xen out/virt6/update-4.4.1-4
> 
> * The signing infrastructure is not in place, so the binaries are not
signed.
> 
> * xend is now disabled by default.  You can enable it by running
> chkconfig.  xend has been removed from the tree entirely in Xen 4.5,
> so this should (hopefully) serve as a "wake-up-call" for people
to
> begin the transition over to xend.
> 
> * A lot have things have changed -- please to test this so we can get
> a good idea what may have broken.
>
I'll test soon. Thanks a lot!

Oh and sorry that I couldn't make it to the Virt SIG call today, I was
busy/offline..

 
>  -George

-- Pasi

On Tue, Dec 16, 2014 at 10:29:53PM +0200, Pasi K?rkk?inen
wrote:
> > 
> > * xend is now disabled by default.  You can enable it by running
> > chkconfig.  xend has been removed from the tree entirely in Xen 4.5,
> > so this should (hopefully) serve as a "wake-up-call" for
people to
> > begin the transition over to xend.
> > 
> > * A lot have things have changed -- please to test this so we can get
> > a good idea what may have broken.
> >
> 
> I'll test soon. Thanks a lot!
> 

Ok I just used a couple of hours testing Xen 4.4.1 rpms on CentOS 6.6 with Linux
3.10 dom0 kernel.
This session was all about xm/xend testing. I manually enabled xend first. 


What Works OK:
	- Manually creating/managing guests with xm and domU cfgfiles in /etc/xen and
LVM volumes as storage (phy backend).
	- Manually creating/managing guests with xm and domU cfgfiles in /etc/xen and
file images as storage (tap2:aio backend).
	- Using virt-install to install PV domUs using LVM volumes as storage (phy
backend).
	- Using virt-manager to install PV domUs using LVM volumes as storage (phy
backend).

What doesn't work:
	- Using virt-manager to install PV domUs using file images as storage (tap:aio
backend).


This libvirt/blktap2 file images failure with Xen 4.4 rpms is a regression from
Xen 4.2 rpms, where blktap2 works OK with libvirt/virt-install/virt-manager.

The problem is most probably the fact that we had custom patches included in the
xen4c6 libvirt rpms that we shipped with the Xen 4.2 rpms.
We had to add two patches, one patch to fix the blktap2 backend type in libvirt,
and one patch to fix the blktap2 backend type in virt-install or virt-manager,
i'm not totally sure which one it was. Those patches should be included in
the earlier libvirt source rpms, so we can check there. Or I can search thru my
emails, because I hunted that down earlier aswell.

It seems we still need those patches with the latest libvirt rpms too.

The actual problem is libvirt/virt-manager tries to configure tap:aio: backend,
which won't work.
It needs to be tap2:aio.

I get the exactly same behaviour with xm/xend. "tap:aio" stalls and
fails. "tap2:aio" works OK.


-- Pasi

On 12/15/2014 12:24 PM, George Dunlap wrote:
> At long last, I've got some beta CentOS 6 4.4.1 packages up on the CBS.
> 
> Major updates include:
> * Update to Xen 4.4.1. Also includes all XSAs through 114
> * Update to latest blktap 2.5
> * Updated libvirt packages (1.2.10), which work well with libxl
> 
> To use, add the following to a file in /etc/yum.repos.d:
> 
> [virt-testing]
> name=CentOS-$releasever - virt-testing
> baseurl=http://cbs.centos.org/repos/virt6-testing/$basearch/os/
> gpgcheck=0
> enabled=1
> 
> Notes:
> * git repo with all the changes to xen can be found here:
>  https://github.com/gwd/sig-virt-xen out/virt6/update-4.4.1-4
> 
> * The signing infrastructure is not in place, so the binaries are not
signed.
> 
> * xend is now disabled by default.  You can enable it by running
> chkconfig.  xend has been removed from the tree entirely in Xen 4.5,
> so this should (hopefully) serve as a "wake-up-call" for people
to
> begin the transition over to xend.
> 
> * A lot have things have changed -- please to test this so we can get
> a good idea what may have broken.
> 
>  -George
George,

I don't mind if xend is on or off, but the virt-manager (virt-install,
etc.) that is included with the current xen4 tree will not work at all
with libxl.

We therefore do not have a GUI front end that can do libxl at this time.

I might suggest leaving xend on for 4.4.x and we stabilize on 4.4.x on
the production branch, and then start a testing branch that will be 4.5
(or newer) with a newer libvirt, virt-manager, qemu, etc.

I thought maybe a new kernel as well, but based on this:

https://www.kernel.org/category/releases.html

It seems 3.10.x (at Sept 2016) is the best LTS kernel for support purposes.

Thanks,
Johnny Hughes

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On 01/06/2015 08:54 AM, Johnny Hughes wrote:
> On 12/15/2014 12:24 PM, George Dunlap wrote:
>> At long last, I've got some beta CentOS 6 4.4.1 packages up on the
CBS.
>>
>> Major updates include:
>> * Update to Xen 4.4.1. Also includes all XSAs through 114
>> * Update to latest blktap 2.5
>> * Updated libvirt packages (1.2.10), which work well with libxl
>>
>> To use, add the following to a file in /etc/yum.repos.d:
>>
>> [virt-testing]
>> name=CentOS-$releasever - virt-testing
>> baseurl=http://cbs.centos.org/repos/virt6-testing/$basearch/os/
>> gpgcheck=0
>> enabled=1
>>
>> Notes:
>> * git repo with all the changes to xen can be found here:
>>  https://github.com/gwd/sig-virt-xen out/virt6/update-4.4.1-4
>>
>> * The signing infrastructure is not in place, so the binaries are not
signed.
>>
>> * xend is now disabled by default.  You can enable it by running
>> chkconfig.  xend has been removed from the tree entirely in Xen 4.5,
>> so this should (hopefully) serve as a "wake-up-call" for
people to
>> begin the transition over to xend.
>>
>> * A lot have things have changed -- please to test this so we can get
>> a good idea what may have broken.
>>
>>  -George
> 
> George,
> 
> I don't mind if xend is on or off, but the virt-manager (virt-install,
> etc.) that is included with the current xen4 tree will not work at all
> with libxl.
> 
> We therefore do not have a GUI front end that can do libxl at this time.
> 
> I might suggest leaving xend on for 4.4.x and we stabilize on 4.4.x on
> the production branch, and then start a testing branch that will be 4.5
> (or newer) with a newer libvirt, virt-manager, qemu, etc.
> 
> I thought maybe a new kernel as well, but based on this:
> 
> https://www.kernel.org/category/releases.html
> 
> It seems 3.10.x (at Sept 2016) is the best LTS kernel for support purposes.
So, I can't read :) .. 3.10.x stops in Sept 2016

Looks like jumping to 3.14.x would be required at some point, might as
well try to do that in the testing branch as well.

Thanks,
JOhnny Hughes


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On Tue, Jan 6, 2015 at 2:54 PM, Johnny Hughes <johnny at centos.org>
wrote:
> George,
>
> I don't mind if xend is on or off, but the virt-manager (virt-install,
> etc.) that is included with the current xen4 tree will not work at all
> with libxl.
>
> We therefore do not have a GUI front end that can do libxl at this time.
>
> I might suggest leaving xend on for 4.4.x and we stabilize on 4.4.x on
> the production branch, and then start a testing branch that will be 4.5
> (or newer) with a newer libvirt, virt-manager, qemu, etc.
Are you sure?  I thought I remembered trying virt-install with libvirt
and having success.  Pasik, did you try this?

If virt-manager really doesn't work with libxl, then yes, we should
probably sort that out one way or another.

I'd really like to be able to leave xend off, to make sure people are
starting to think about migration; but if there's no way to get
virt-manager to work without it, we'll just have to turn xend back on
and see what we can do.
> I thought maybe a new kernel as well, but based on this:
Yes, updating to a new kernel (probably 3.14) is my next big work item.

 -George