Xen devel - Jun 2012 - [Xen-users] Why the need for "-f" with XL in Xen 4.2 rev-25467

Just out of annoyance more than curiosity, but ever since I started 
using Xen 4.2-unstable rev-25467, every time I try to run "sudo xl 
create <domu_config_file>", or "sudo xl reboot", or
"sudo xl destroy",
it always gives me this message:

"*xend is running, which prevents xl from working correctly.
If you still want to force the execution of xl please use the -f option*"

I am now forced to use the "-f" option anytime i am using the xl 
toolstack. It never used to be that way going back to Xen 4.2-unstable 
rev-25459. I was reading something about this a while ago on the 
Xen-devel list, but forget what.

SOOO, any logical reason for the need to use the FORCE option every time 
you run the XL command? AND assuming it is not something on my setup 
that is causing it, will it always stay like this in future revisions?

Thank you for any enlightening


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On Thu, Jun 21, 2012 at 2:34 AM,  <cyberhawk001@gmail.com>
wrote:
> Just out of annoyance more than curiosity, but ever since I started using
> Xen 4.2-unstable rev-25467, every time I try to run "sudo xl create
> <domu_config_file>", or "sudo xl reboot", or
"sudo xl destroy", it always
> gives me this message:
>
> "xend is running, which prevents xl from working correctly.
> If you still want to force the execution of xl please use the -f
option"
>
> I am now forced to use the "-f" option anytime i am using the xl
toolstack.
> It never used to be that way going back to Xen 4.2-unstable rev-25459. I
was
> reading something about this a while ago on the Xen-devel list, but forget
> what.
>
> SOOO, any logical reason for the need to use the FORCE option every time
you
> run the XL command? AND assuming it is not something on my setup that is
> causing it, will it always stay like this in future revisions?
>
Xend and xl are part of different toolstacks and should not be used
together. You should investigate why you have xend running, most
likely it shouldn''t be.

Xen 4.2 and newer have the xl toolstack as default.
Xen 4.1 and older have the xend/xm toolstack as default.

See http://wiki.xen.org/wiki/Choice_of_Toolstacks for more info.

On 6/20/2012 10:07 PM, Rolu wrote:
> On Thu, Jun 21, 2012 at 2:34 AM,<cyberhawk001@gmail.com>  wrote:
>> Just out of annoyance more than curiosity, but ever since I started
using
>> Xen 4.2-unstable rev-25467, every time I try to run "sudo xl
create
>> <domu_config_file>", or "sudo xl reboot", or
"sudo xl destroy", it always
>> gives me this message:
>>
>> "xend is running, which prevents xl from working correctly.
>> If you still want to force the execution of xl please use the -f
option"
>>
>> I am now forced to use the "-f" option anytime i am using the
xl toolstack.
>> It never used to be that way going back to Xen 4.2-unstable rev-25459.
I was
>> reading something about this a while ago on the Xen-devel list, but
forget
>> what.
>>
>> SOOO, any logical reason for the need to use the FORCE option every
time you
>> run the XL command? AND assuming it is not something on my setup that
is
>> causing it, will it always stay like this in future revisions?
>>
> Xend and xl are part of different toolstacks and should not be used
> together. You should investigate why you have xend running, most
> likely it shouldn''t be.
>
> Xen 4.2 and newer have the xl toolstack as default.
> Xen 4.1 and older have the xend/xm toolstack as default.
>
> Seehttp://wiki.xen.org/wiki/Choice_of_Toolstacks  for more info.
Yes i know the difference between XL and XM toolstacks and have been 
using Xen 4.2-unstable with XL since the beginning of my Xen journey. As 
i mentioned before, i never had this issue with a previous Xen 4.2 
person as i mentioned it, HOWEVER i have messed around with XCP and 
different version of Xen on this Debian before, SO very likely i forgot 
to remove or uninstall something between changes, just trying to figure 
out how to make it stop asking me to force anything.

I was checking to make sure XEND was stopped by running "*sudo 
/etc/init.d/xend stop*" and i get an error message as below:

*Traceback (most recent call last):
   file "usr/sbin/xen", line 36, in <module>
     from xen.xend.server import SrvDaemon
ImportError: No module named xen.xend.server*

WHICH also happens to be the exact same message i have been getting 
every time i shut down Dom0 for quite a while now and been meaning to 
ask about that.

Once i run "*sudo update-rc.d xend stop*" than i am able to run
"*sudo
xl create*" without the FORCE option, but once i reboot the system, it 
comes back and have to run the "*sudo update-rc.d xend stop*" all over
again. SO wondering how to disable xend from loading at boot time? Or 
just get rid of whatever remnants floating around that is interfering 
with things.





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On Thu, 2012-06-21 at 03:52 +0100, cyberhawk001@gmail.com wrote:
> Once i run "sudo update-rc.d xend stop" than i am able to run
"sudo xl
> create" without the FORCE option, but once i reboot the system, it
> comes back and have to run the "sudo update-rc.d xend stop" all
over
> again. SO wondering how to disable xend from loading at boot time? Or
> just get rid of whatever remnants floating around that is interfering
> with things.
You need to remove the initscript which is starting xend on boot. Try
"update-rc.d xend disable".

The reason for this check to prevent xl from running while xend is
active is that using xl while xend is running can lead to subtle and
confusing bugs.

Ian.

On Thu, Jun 21, 2012 at 6:20 AM, Ian Campbell <Ian.Campbell@citrix.com>
wrote:
> The reason for this check to prevent xl from running while xend is
> active is that using xl while xend is running can lead to subtle and
> confusing bugs.
Just to emphasize the point: about a month ago I spent 3 full days
trying to track down what I thought was an ugly reference-counting
error on domain destruction, but turned out just to be xend running in
the background and messing with things behind xl''s back. 
That''s what
prompted us to put in the check. :-)

Perhaps the warning should explicitly mentioning disabling xend as the
best solution?

 -George

On Thu, 2012-06-21 at 12:40 +0100, George Dunlap wrote:
> On Thu, Jun 21, 2012 at 6:20 AM, Ian Campbell
<Ian.Campbell@citrix.com> wrote:
> > The reason for this check to prevent xl from running while xend is
> > active is that using xl while xend is running can lead to subtle and
> > confusing bugs.
> 
> Just to emphasize the point: about a month ago I spent 3 full days
> trying to track down what I thought was an ugly reference-counting
> error on domain destruction, but turned out just to be xend running in
> the background and messing with things behind xl''s back. 
That''s what
> prompted us to put in the check. :-)
> 
> Perhaps the warning should explicitly mentioning disabling xend as the
> best solution?
Yes, I think that would be a good idea.
> 
>  -George