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Old 07-05-2011, 11:22 PM
Justin Ryan
 
Default Roadmap: Xen revisited

Howdy!
I came across the Oneiric server roadmap today and saw some sensible items regarding Xen support which align with work I've been meaning to do for some time, as well as the quoted recent short thread.

I'd like to volunteer to help with this work, I did a lot of work with Xen on Ubuntu over the past couple of years, mostly 3.4 and 4.0 beta on karmic, and am now revisiting with a goal of converting a number of kvm hosts to Xen, which I believe will yield better performance.

I'm very familiar with dom0 pvops support and would happily work with the kernel team, as well as refreshing the debian xen packages to 4.1, which has some really great functionality.

-- snip --
On 03/30/2011 08:27 AM, Chuck Short wrote:
> Hi,
>
> In the past Xen support in Ubuntu as a host has been difficult for a
> variety of reasons most notably no upstream kernel support. Now that
> dom0 should be coming into the vanilla kernel soon. I think its time to
> revisit supporting Xen as a hypervisor as well.
>
> Regards
> chuck
>
Hi there,

Linus just accepted almost all the xen bits in 2.6.39+, this will allow
Linux to run in Xen as Domain-0 and DomainU fully paravirtulized, more info:

http://blogs.oracle.com/wim/entry/linux_mainline_contains_all_the?

http://www.kernel.org/diff/diffview.cgi?file=/pub/linux/kernel/v2.6/snapshots/patch-2.6.39-git20.bz2

Best regards.
-- snip --
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Old 07-06-2011, 12:31 PM
Chuck Short
 
Default Roadmap: Xen revisited

Hi Justin,

I am the developer assigned to the specification, alot of the work has
already been done. We have the dom0 enabled in the kernel and have the
package synced from Debian. Right now we need more testing and opening
the bug reports. If you want to contact me off list that would be great
as well.

chuck

On Tue, 5 Jul 2011 16:22:03 -0700
Justin Ryan <justizin@justizin.com> wrote:

> Howdy!
>
> I came across the Oneiric server roadmap today and saw some sensible
> items regarding Xen support which align with work I've been meaning
> to do for some time, as well as the quoted recent short thread.
>
> I'd like to volunteer to help with this work, I did a lot of work
> with Xen on Ubuntu over the past couple of years, mostly 3.4 and 4.0
> beta on karmic, and am now revisiting with a goal of converting a
> number of kvm hosts to Xen, which I believe will yield better
> performance.
>
> I'm very familiar with dom0 pvops support and would happily work with
> the kernel team, as well as refreshing the debian xen packages to
> 4.1, which has some really great functionality.
>
> -- snip --
>
> On 03/30/2011 08:27 AM, Chuck Short wrote:
> >* Hi,*>**>* In the past Xen support in Ubuntu as a host has been
> >difficult for a*>* variety of reasons most notably no upstream
> >kernel support. Now that*>* dom0 should be coming into the vanilla
> >kernel soon. I think its time to*>* revisit supporting Xen as a
> >hypervisor as well.*>**>* Regards*>* chuck*>**Hi there,
>
> Linus just accepted almost all the xen bits in 2.6.39+, this will
> allow Linux to run in Xen as Domain-0 and DomainU fully
> paravirtulized, more info:
> http://blogs.oracle.com/wim/entry/linux_mainline_contains_all_the?
> http://www.kernel.org/diff/diffview.cgi?file=/pub/linux/kernel/v2.6/snapshots/patch-2.6.39-git20.bz2
>
> Best regards.
>
> -- snip --
>
> --
> http://about.me/justizin


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Old 07-19-2011, 10:29 PM
Mark Goldfinch
 
Default Roadmap: Xen revisited

On 07/07/11 00:31, Chuck Short wrote:

I am the developer assigned to the specification, alot of the work has
already been done. We have the dom0 enabled in the kernel and have the
package synced from Debian. Right now we need more testing and opening
the bug reports. If you want to contact me off list that would be great
as well.


I have an oneiric domu install on a Debian 6 dom0. My domu has a single / mount-point using ext4.
The dom0 uses an lvm2 block device to present this disk to the domu.


Currently if I use pygrub and boot the oneiric 3.0.0-5 kernel my root filesystem gets remounted
read-only:


[ 9.077887] end_request: I/O error, dev xvda2, sector 8651288
[ 9.078258] end_request: I/O error, dev xvda2, sector 8651288
[ 9.078642] Aborting journal on device xvda2-8.
[ 9.101709] EXT4-fs error (device xvda2): ext4_journal_start_sb:296: Detected aborted journal
[ 9.101730] EXT4-fs (xvda2): Remounting filesystem read-only

Currently I work-around this by booting the 2.6.32-5-xen Debian 6.0 kernel, but that means I end up
running up against https://bugs.launchpad.net/ubuntu/lucid/+source/rsyslog/+bug/523610 which is less
than ideal.


I note there is mention in the server team minutes saying Xen has several issues, but I can't seem
to find this particular issue within Launchpad?


Thanks,
Mark Goldfinch.

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Old 07-20-2011, 09:12 AM
Stefan Bader
 
Default Roadmap: Xen revisited

On 20.07.2011 00:29, Mark Goldfinch wrote:
> On 07/07/11 00:31, Chuck Short wrote:
>> I am the developer assigned to the specification, alot of the work has
>> already been done. We have the dom0 enabled in the kernel and have the
>> package synced from Debian. Right now we need more testing and opening
>> the bug reports. If you want to contact me off list that would be great
>> as well.
>
> I have an oneiric domu install on a Debian 6 dom0. My domu has a single /
> mount-point using ext4. The dom0 uses an lvm2 block device to present this disk
> to the domu.
>
> Currently if I use pygrub and boot the oneiric 3.0.0-5 kernel my root filesystem
> gets remounted read-only:
>
> [ 9.077887] end_request: I/O error, dev xvda2, sector 8651288
> [ 9.078258] end_request: I/O error, dev xvda2, sector 8651288
> [ 9.078642] Aborting journal on device xvda2-8.
> [ 9.101709] EXT4-fs error (device xvda2): ext4_journal_start_sb:296: Detected
> aborted journal
> [ 9.101730] EXT4-fs (xvda2): Remounting filesystem read-only
>
> Currently I work-around this by booting the 2.6.32-5-xen Debian 6.0 kernel, but
> that means I end up running up against
> https://bugs.launchpad.net/ubuntu/lucid/+source/rsyslog/+bug/523610 which is
> less than ideal.
>
> I note there is mention in the server team minutes saying Xen has several
> issues, but I can't seem to find this particular issue within Launchpad?
>
> Thanks,
> Mark Goldfinch.
>

The several issues rather being related to run the dom0. I still see some
warnings getting triggered which seem to be harmless enough. And HVM is not
working. There is another minor issue when you have sd* disk names in your pv
configuration (which is actually discouraged).

Otherwise I have PVM domUs working with our 3.0-rc7 based dom0. Not sure what
the Debian 6 dom0 is based on. The blkback was the one thing that went upstream
quite late. But since we had been following the 3.0 kernel, we would have picked
up any fixes there automatically.

-Stefan

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Old 07-20-2011, 09:30 AM
Mark Goldfinch
 
Default Roadmap: Xen revisited

On 20/07/11 21:12, Stefan Bader wrote:

The several issues rather being related to run the dom0. I still see some
warnings getting triggered which seem to be harmless enough. And HVM is not
working. There is another minor issue when you have sd* disk names in your pv
configuration (which is actually discouraged).


Great, thanks for the clarification..


Otherwise I have PVM domUs working with our 3.0-rc7 based dom0. Not sure what
the Debian 6 dom0 is based on. The blkback was the one thing that went upstream
quite late. But since we had been following the 3.0 kernel, we would have picked
up any fixes there automatically.


Debian 6 dom0 uses 2.6.32 Linux kernel and 4.0.1 Xen Hypervisor kernel. I'm using amd64 architecture.

What can I do to help diagnose what's going on here?

Thanks,
Mark.

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Old 07-20-2011, 11:43 AM
Stefan Bader
 
Default Roadmap: Xen revisited

On 20.07.2011 11:30, Mark Goldfinch wrote:
> On 20/07/11 21:12, Stefan Bader wrote:
>> The several issues rather being related to run the dom0. I still see some
>> warnings getting triggered which seem to be harmless enough. And HVM is not
>> working. There is another minor issue when you have sd* disk names in your pv
>> configuration (which is actually discouraged).
>
> Great, thanks for the clarification..
>
>> Otherwise I have PVM domUs working with our 3.0-rc7 based dom0. Not sure what
>> the Debian 6 dom0 is based on. The blkback was the one thing that went upstream
>> quite late. But since we had been following the 3.0 kernel, we would have picked
>> up any fixes there automatically.
>
> Debian 6 dom0 uses 2.6.32 Linux kernel and 4.0.1 Xen Hypervisor kernel. I'm
> using amd64 architecture.
>
> What can I do to help diagnose what's going on here?
>
> Thanks,
> Mark.
>
In the end (as its Debians dom0) there should be a debian bug opened. Of
interest likely is:

- clear statement about last running domU (2.6.? -> 3.0 regression?)
- the used configuration file
- is root= using a device name or label or uuid (boot loader)?
- dmesg from any last working case and the failing one
- check xm log / xm dmesg for hints
- try to rule out the boot loader by extracting initrd and vmlinuz and
using kernel and ramdisk pointing to those in the cfg file instead.

So I'd probably play around with those hints, especially the boot loader test. I
am using pvgrub on both the Oneiric dom0 and a CentOS based dom0 and both were
working for me.

-Stefan

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Old 07-21-2011, 04:16 PM
Justin Ryan
 
Default Roadmap: Xen revisited

Howdy Mark!

On Tue, Jul 19, 2011 at 3:29 PM, Mark Goldfinch <ubuntu-server@g.org.nz> wrote:
*



Currently if I use pygrub and boot the oneiric 3.0.0-5 kernel my root filesystem gets remounted read-only:


Have you tried pvgrub? *Last I checked, and it was a while ago, pygrub is deprecated. *Possibly as far back as Xen 3.4.

In many situations you will likely have the same result, but it's good to remove that variable IMO.
Best!
Justin*
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