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Paul van der Vlis 05-29-2008 01:17 PM

Xen question
 
Hello,

I have some questions about Xen:

- I have installed an AMD64 Xen machine with Etch. In unstable I don't
see Xen-AMD64 kernels anymore. Is there a change that Xen-AMD64 support
will be dropped?

- I see that my amd64-guest has only one CPU, but it is a multicore
machine. Will I use only one core?

- When I reboot my machine, the guests boot nicely. But when I have a
power loss and the power returns, the guests do not start. What will be
wrong?

- I have a time-problem. The time in my Xen guests is 2 hours earlier
then in the domO. I have a correct /etc/timezone in both. I have now
made them independend with /proc/sys/xen/independent_wallclock, but I
would prefer to user them synchronised. But how?

With regards,
Paul van der Vlis.




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Stephen Gran 05-29-2008 04:08 PM

Xen question
 
This one time, at band camp, Paul van der Vlis said:
> Hello,
>
> I have some questions about Xen:
>
> - I have installed an AMD64 Xen machine with Etch. In unstable I don't
> see Xen-AMD64 kernels anymore. Is there a change that Xen-AMD64 support
> will be dropped?

Kernels > 2.6.18 do not support Xen dom0 on any architecture, as far as
I'm aware.

> - I see that my amd64-guest has only one CPU, but it is a multicore
> machine. Will I use only one core?

It depends on how many CPUs you export to the guest. See your config
file for how many you export.

> - When I reboot my machine, the guests boot nicely. But when I have a
> power loss and the power returns, the guests do not start. What will be
> wrong?

This I don't know - if you have the config files in /etc/xen/auto
the guests should boot on startup no matter why it went down.

> - I have a time-problem. The time in my Xen guests is 2 hours earlier
> then in the domO. I have a correct /etc/timezone in both. I have now
> made them independend with /proc/sys/xen/independent_wallclock, but I
> would prefer to user them synchronised. But how?

I'm guesing you're +/- 2hours from UTC?

Run tzconfig in the domU. For some reason this bites me fairly often
when bootstrapping a new guest. I guess something doesn't work right
in the debootstrap environment and it has to be cleaned up manually
afterwards.
--
-----------------------------------------------------------------
| ,'`. Stephen Gran |
| : :' : sgran@debian.org |
| `. `' Debian user, admin, and developer |
| `- http://www.debian.org |
-----------------------------------------------------------------

Anders Breindahl 05-29-2008 05:12 PM

Xen question
 
On 200805291708, Stephen Gran wrote:
> This one time, at band camp, Paul van der Vlis said:
> > I have some questions about Xen:
> >
> > - I have installed an AMD64 Xen machine with Etch. In unstable I don't
> > see Xen-AMD64 kernels anymore. Is there a change that Xen-AMD64 support
> > will be dropped?
>
> Kernels > 2.6.18 do not support Xen dom0 on any architecture, as far as
> I'm aware.

I second that. There's a Redhat effort to make a dom0-able kernel. So
far there's (has been?) a .20-series domU-kernel in unstable for i386.

In fact, the situation is so grave that people are considering
contingency plans. It could seem that Xen is dying slowly -- I'm not
saying it is, but I'm saying it seems to be.

For further such issues, the pkg-xen-devel list on alioth should be
visited.

> > - I see that my amd64-guest has only one CPU, but it is a multicore
> > machine. Will I use only one core?
>
> It depends on how many CPUs you export to the guest. See your config
> file for how many you export.

It's the vcpus = n directive you're lacking. In that fashion, more than
a single raw-steel processor will be used on the domU at a time. (Though
if you have multiple domU's, there's a natural evening of workload, even
though they each have only one CPU accessible.)

> > - When I reboot my machine, the guests boot nicely. But when I have a
> > power loss and the power returns, the guests do not start. What will be
> > wrong?
>
> This I don't know - if you have the config files in /etc/xen/auto
> the guests should boot on startup no matter why it went down.

It's probably related to the fact that Debian's Xen by default runs a
`xm save` (IIRC) on the domains during shutdown to have the `xm
restore`'ed on next bootup. -- But that only applies to clean shutdowns.

> > - I have a time-problem. The time in my Xen guests is 2 hours earlier
> > then in the domO. I have a correct /etc/timezone in both. I have now
> > made them independend with /proc/sys/xen/independent_wallclock, but I
> > would prefer to user them synchronised. But how?
>
> I'm guesing you're +/- 2hours from UTC?
>
> Run tzconfig in the domU. For some reason this bites me fairly often
> when bootstrapping a new guest. I guess something doesn't work right
> in the debootstrap environment and it has to be cleaned up manually
> afterwards.

I have that experience too.

Regards, skrewz.

Paul van der Vlis 05-30-2008 09:09 AM

Xen question
 
Stephen Gran schreef:
> This one time, at band camp, Paul van der Vlis said:
>> Hello,
>>
>> I have some questions about Xen:
>>
>> - I have installed an AMD64 Xen machine with Etch. In unstable I don't
>> see Xen-AMD64 kernels anymore. Is there a change that Xen-AMD64 support
>> will be dropped?
>
> Kernels > 2.6.18 do not support Xen dom0 on any architecture, as far as
> I'm aware.

Will this not do it?
http://packages.debian.org/sid/linux-image-2.6.25-2-xen-686

So far I know, the kernel from kernel.org allready have support for
domU's since kernel 2.6.23. Why would there be a special xen-kernel if
the normal kernel allready supports it?

>> - I see that my amd64-guest has only one CPU, but it is a multicore
>> machine. Will I use only one core?
>
> It depends on how many CPUs you export to the guest. See your config
> file for how many you export.

I've tried to change the "VCPU" in de guest, but it still sees 1 CPU.
Maybe there is no SMP support for the guest?

>> - When I reboot my machine, the guests boot nicely. But when I have a
>> power loss and the power returns, the guests do not start. What will be
>> wrong?
>
> This I don't know - if you have the config files in /etc/xen/auto
> the guests should boot on startup no matter why it went down.

I saw in the configfile:

on_poweroff = 'destroy'
on_reboot = 'restart'
on_crash = 'restart'

Maybe a power loss is managed with "on_poweroff", I will check that.

>> - I have a time-problem. The time in my Xen guests is 2 hours earlier
>> then in the domO. I have a correct /etc/timezone in both. I have now
>> made them independend with /proc/sys/xen/independent_wallclock, but I
>> would prefer to user them synchronised. But how?
>
> I'm guesing you're +/- 2hours from UTC?

Yes ;-)

> Run tzconfig in the domU. For some reason this bites me fairly often
> when bootstrapping a new guest. I guess something doesn't work right
> in the debootstrap environment and it has to be cleaned up manually
> afterwards.

You are right, thanks. I also found that you can do this in Lenny/Sid
with "dpkg-reconfigure tzdata" (I have the same problem in a Sid chroot).

So far I know, the kernel Xen-stuff comes from from Fedora. Fedora 9 is
released, but the Xen stuff was not ready:
http://fedoraproject.org/wiki/Features/XenPvops

Thanks for your help!

With regards,
Paul van der Vlis.
Groningen, Netherlands.



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Paul van der Vlis 05-30-2008 09:41 AM

Xen question
 
Anders Breindahl schreef:
> On 200805291708, Stephen Gran wrote:
>> This one time, at band camp, Paul van der Vlis said:
>>> I have some questions about Xen:
>>>
>>> - I have installed an AMD64 Xen machine with Etch. In unstable I don't
>>> see Xen-AMD64 kernels anymore. Is there a change that Xen-AMD64 support
>>> will be dropped?
>> Kernels > 2.6.18 do not support Xen dom0 on any architecture, as far as
>> I'm aware.
>
> I second that. There's a Redhat effort to make a dom0-able kernel. So
> far there's (has been?) a .20-series domU-kernel in unstable for i386.
>
> In fact, the situation is so grave that people are considering
> contingency plans. It could seem that Xen is dying slowly -- I'm not
> saying it is, but I'm saying it seems to be.

Oeps, a serious thing...

I saw Ubuntu has Xen support in kernel 2.6.24 (in "universe", so no
security support).
http://packages.ubuntu.com/hardy/linux-image-2.6.24-16-xen

> For further such issues, the pkg-xen-devel list on alioth should be
> visited.

I am a member, but there is not so much responce on that list.

With regards,
Paul van der Vlis.




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Lionel Porcheron 06-01-2008 05:34 PM

Xen question
 
Paul van der Vlis a écrit :
>> In fact, the situation is so grave that people are considering
>> contingency plans. It could seem that Xen is dying slowly -- I'm not
>> saying it is, but I'm saying it seems to be.
>
> Oeps, a serious thing...
>
> I saw Ubuntu has Xen support in kernel 2.6.24 (in "universe", so no
> security support).
> http://packages.ubuntu.com/hardy/linux-image-2.6.24-16-xen

This is a port from RedHat Xen support to Ubuntu Kernel.

As a side note, beeing in universe in Ubuntu does not mean no security
support, but security support provided by community (not Canonical).

Cheers,

Lionel




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Paul van der Vlis 06-02-2008 06:54 PM

Xen question
 
Anders Breindahl schreef:
> On 200805291708, Stephen Gran wrote:
>> This one time, at band camp, Paul van der Vlis said:
>>> I have some questions about Xen:
>>>
>>> - I have installed an AMD64 Xen machine with Etch. In unstable I don't
>>> see Xen-AMD64 kernels anymore. Is there a change that Xen-AMD64 support
>>> will be dropped?
>> Kernels > 2.6.18 do not support Xen dom0 on any architecture, as far as
>> I'm aware.
>
> I second that. There's a Redhat effort to make a dom0-able kernel. So
> far there's (has been?) a .20-series domU-kernel in unstable for i386.
>
> In fact, the situation is so grave that people are considering
> contingency plans. It could seem that Xen is dying slowly -- I'm not
> saying it is, but I'm saying it seems to be.
>
> For further such issues, the pkg-xen-devel list on alioth should be
> visited.
>
>>> - I see that my amd64-guest has only one CPU, but it is a multicore
>>> machine. Will I use only one core?
>> It depends on how many CPUs you export to the guest. See your config
>> file for how many you export.
>
> It's the vcpus = n directive you're lacking. In that fashion, more than
> a single raw-steel processor will be used on the domU at a time. (Though
> if you have multiple domU's, there's a natural evening of workload, even
> though they each have only one CPU accessible.)

I am not sure what I did wrong before, but now it works with the vcpus
directive. Great!

With regards,
Paul van der Vlis.




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06-11-2008 03:21 PM

Xen question
 
Paul van der Vlis wrote:

>>> - When I reboot my machine, the guests boot nicely. But when I have a
>>> power loss and the power returns, the guests do not start. What will be
>>> wrong?
>> This I don't know - if you have the config files in /etc/xen/auto
>> the guests should boot on startup no matter why it went down.
>
> I saw in the configfile:
>
> on_poweroff = 'destroy'
> on_reboot = 'restart'
> on_crash = 'restart'
>
> Maybe a power loss is managed with "on_poweroff", I will check that.

These directives are related to the states of your virtual machines, not
the dom0. "on_poweroff" is declaring what should happen to the VM when
you choose to power it off, not what happens when you shutdown dom0.

Regards,
Kim
--
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|_|_|O| Public key: http://rac.nu/kchr.asc
|O|O|O| Web home: http://blog.technopragmatics.org

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Paul van der Vlis 06-11-2008 06:57 PM

Xen question
 
kchr-list-debian@rac.nu schreef:
> Paul van der Vlis wrote:
>
>>>> - When I reboot my machine, the guests boot nicely. But when I have a
>>>> power loss and the power returns, the guests do not start. What will be
>>>> wrong?
>>> This I don't know - if you have the config files in /etc/xen/auto
>>> the guests should boot on startup no matter why it went down.
>> I saw in the configfile:
>>
>> on_poweroff = 'destroy'
>> on_reboot = 'restart'
>> on_crash = 'restart'
>>
>> Maybe a power loss is managed with "on_poweroff", I will check that.
>
> These directives are related to the states of your virtual machines, not
> the dom0. "on_poweroff" is declaring what should happen to the VM when
> you choose to power it off, not what happens when you shutdown dom0.

I have tried it and I use now: on_poweroff = 'restart'

I expect that when I have a powerloss and the server comes up again, the
virtual machines are restarting now, but I have not tested it.
With on_poweroff = 'destroy' this was not the case.

With regards,
Paul van der Vlis.




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06-16-2008 09:08 AM

Xen question
 
Paul van der Vlis wrote:

> kchr-list-debian@rac.nu schreef:
>> Paul van der Vlis wrote:
>>
>>>>> - When I reboot my machine, the guests boot nicely. But when I have a
>>>>> power loss and the power returns, the guests do not start. What will be
>>>>> wrong?
>>>> This I don't know - if you have the config files in /etc/xen/auto
>>>> the guests should boot on startup no matter why it went down.
>>> I saw in the configfile:
>>>
>>> on_poweroff = 'destroy'
>>> on_reboot = 'restart'
>>> on_crash = 'restart'
>>>
>>> Maybe a power loss is managed with "on_poweroff", I will check that.
>> These directives are related to the states of your virtual machines, not
>> the dom0. "on_poweroff" is declaring what should happen to the VM when
>> you choose to power it off, not what happens when you shutdown dom0.
>
> I have tried it and I use now: on_poweroff = 'restart'
>
> I expect that when I have a powerloss and the server comes up again, the
> virtual machines are restarting now, but I have not tested it.
> With on_poweroff = 'destroy' this was not the case.

Basically, what "on_poweroff = 'restart'" does is just to restart the VM
if you choose to shut it down through the VM OS. It has nothing to do
with the fact that your VMs aren't booting automatically if your host
(dom0) has a power outage.

Regards,
Kim
--
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|_|_|O| Public key: http://rac.nu/kchr.asc
|O|O|O| Web home: http://blog.technopragmatics.org

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