Re: [Xen-users] RHEL6 domU migrate issues w/ higher to lower frequency CPU's

[Paras pradhan <pradhanparas@xxxxxxxxx>]

On Thu, Dec 16, 2010 at 12:58 PM, Joshua West <jwest@xxxxxxxxxxxx> wrote:
> Hi Paras,
>
> In what way does your migration fail?  Does it succeed but then the virtual
> machine is then completely unresponsive, including the console?  Or does the
> migration just error/exit out?

Yes. Migration is successful each time I migrate. No error. Xen dom0s
logs looks normal too.

>
> I've heard reports of problems like this with the stock RHEL 5.x Xen
> software, regardless of CPU MHz clock speed, having issues.  In my case, it
> only seems to be a problem when moving from servers with higher/faster CPU
> MHz clock speeds to those with lower.  Also, it now looks like the console
> finally becomes responsive after about 5-10 minutes of being hung up.

Well I have similar CPUs on all the nodes.
>
> I've opened a case with Red Hat as well:
>  https://bugzilla.redhat.com/show_bug.cgi?id=663755

Great ...
>
> I'm interested to see if this is the same bug you and I are experiencing or
> if its two different issues, as I'm running a later version of Xen.

When I created a case with Redhat , they told me they are not able to
reproduce the issue. I have provided all my setup config files to them
and now I am waiting from a week. But I am sure this has to do with
redhat 6 domU kernel.  No problem with redhat 5 domUs.


Hope we will find the solution soon.

Thanks!
Paras.
>
> Thanks for the input!
>
> On 12/16/10 10:40, Paras pradhan wrote:
>>
>> I am having exactly the same problem. Plus this bug is seen when you
>> have the same cpu in both nodes too. I have tested in Quad-Core AMD
>> Opteron(tm) Processor 8374 HE in both nodes and same problem.
>>
>> Symptoms:
>>
>> * Start the node in node1. No problem
>> * Live migrate to Node2 (same cpu, 100% same hardware). domU
>> unresponsive, no output in xm console, can ping ,can see ssh banner
>> but dead slow
>> * Migrate back in node1, No problem
>>
>> I could reproduce this problem in another set of systems too. Same
>> problem.
>>
>> I have a ticket opened with Redhat from around 2 weeks. no help till now.
>>
>> Also I have seen this bug filed at Redhat but dunno if they are
>> working on it or not.
>> https://bugzilla.redhat.com/show_bug.cgi?id=613513
>>
>> This is really frustrating.
>>
>> Paras.
>>
>>
>> On Wed, Dec 15, 2010 at 5:03 PM, Joshua West<jwest@xxxxxxxxxxxx>  wrote:
>>>
>>> Hey folks,
>>>
>>> I've encountered a rather interesting/frustrating issue with RHEL6 domU's
>>> and live migration.
>>>
>>> I have no problems booting a RHEL6 domU using its stock/native kernel on
>>> Xen
>>> 3.4.1 or Xen 3.4.3.  But in terms of live migration, there seems to be a
>>> problem when moving from a higher (in terms of CPU MHz) to lower (MHz)
>>> system -- even if the higher of the two is a much older CPU model.
>>>
>>> For example, I can reproduce the bug under Xen 3.4.3 with the following:
>>>
>>>  * Migrating from X5450 @ 3.00GHz to X5355 @ 2.66GHz fails, but the
>>> opposite
>>> (increasing in CPU frequency) succeeds.
>>>  * Migrating from Xeon(TM) CPU 2.80GHz to E5310 @ 1.60GHz fails, but the
>>> opposite (increasing in CPU frequency) succeeds.
>>>
>>> BTW, when I say "fails", what I really mean is the migration succeeds but
>>> the domU is no longer responsive.  I can attach to the console via 'xm
>>> console' but nothing is displayed, although occasionally a new line is
>>> printed as i bang my hands on the Enter key.  Occasionally ping works and
>>> occasionally I can establish a connection to the domU's port 22 and see
>>> the
>>> OpenSSH banner, but thats as far as I get.  Its not like the domU is
>>> runaway
>>> with 100% cpu.  It sits with state "-b----" (xm list).
>>>
>>> I have tested cpuid masking but this doesn't help.  Its an issue with
>>> going
>>> from a higher CPU frequency system to a lower CPU frequency system.
>>>
>>> This is using the stock RHEL6 kernel 'vmlinuz-2.6.32-71.7.1.el6.x86_64'.
>>>
>>> Anybody have suggestions on the cause or a workaround?  Experience this
>>> issue too?
>>>
>>> I've heard through the grapevine that this bug is also confirmed with
>>> RHEL6
>>> domU's on XCP 1.0.
>>>
>>> Thanks for any help you can provide!
>>>
>>> --
>>> Joshua West
>>> Senior Systems Engineer
>>> Brandeis University
>>> http://www.brandeis.edu
>>>
>>>
>>> _______________________________________________
>>> Xen-users mailing list
>>> Xen-users@xxxxxxxxxxxxxxxxxxx
>>> http://lists.xensource.com/xen-users
>>>
>> _______________________________________________
>> Xen-users mailing list
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>> http://lists.xensource.com/xen-users
>
>
> --
> Joshua West
> Senior Systems Engineer
> Brandeis University
> http://www.brandeis.edu
>
>
> _______________________________________________
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> http://lists.xensource.com/xen-users
>

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