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From John Burwell <jburw...@basho.com>
Subject Re: [VOTE] Move forward with 4.1 without a Xen-specific fix for CLOUDSTACK-2492?
Date Tue, 21 May 2013 00:26:21 GMT
Chip,

Previous releases of CloudStack may have set /proc/sys/xen/independent_wallclock in the cloud-early-config
script which will properly sync clock for paravirtualized VMs.  However, NTP is only solution
that correct clock drift for both para and full virtualized VMs.  Admittedly, I haven't looked
in the history to see if this strategy was previously employed.

Thanks,
-John


On May 20, 2013, at 8:18 PM, Chip Childers <chip.childers@sungard.com> wrote:

> On May 20, 2013, at 7:14 PM, John Burwell <jburwell@basho.com> wrote:
> 
>> All,
>> 
>> While it is tough to do, I must cast a -1 for the following reasons:
>> 
>> Given that system VMs write files, this defect makes every file created/modified
timestamp unreliable.
>> Operational log correlation/debugging is nearly impossible since the clock is out
of sync.
>> It renders S3-backed Secondary Storage unreliable/useless
>> 
>> As Ahmad pointed out, there are likely other instabilities/defects lurking due to
this issue that we haven't discovered.
>> 
>> I think we also need to determine whether or not this issue was introduced in 4.1.
 If not, we should consider back porting these fixes.
> 
> It can't be this, because the system VM's for 4.1 are the exact same
> images since 3.x releases.
> 
>> 
>> Thanks,
>> -John
>> 
>> On May 20, 2013, at 5:29 PM, Ahmad Emneina <aemneina@gmail.com> wrote:
>> 
>>> I'm +0 on this, dont want to hold up a release with a neg 1 vote. My
>>> opinion is that time sync is critical piece for system vm's. Having the
>>> wrong time can lead to system vm's booting and waiting for manual
>>> intervention via consistency checks (potential blocker bug IMO).
>>> 
>>> 
>>> On Mon, May 20, 2013 at 2:03 PM, Chiradeep Vittal <
>>> Chiradeep.Vittal@citrix.com> wrote:
>>> 
>>>> +1
>>>> 
>>>> On 5/20/13 1:15 PM, "Chip Childers" <chip.childers@sungard.com> wrote:
>>>> 
>>>>> All,
>>>>> 
>>>>> As discussed on another thread [1], we identified a bug
>>>>> (CLOUDSTACK-2492) in the current 3.x system VMs, where the System VMs
>>>>> are not configured to sync their time with either the host HV or an NTP
>>>>> service.  That bug affects the system VMs for all three primary HVs (KVM,
>>>>> Xen and vSphere).  Patches have been committed addressing vSphere and
>>>>> KVM.  It appears that a correction for Xen would require the re-build
of
>>>>> a system VM image and a full round of regression testing that image.
>>>>> 
>>>>> Given that the discussion thread has not resulted in a consensus on this
>>>>> issue, I unfortunately believe that the only path forward is to call
for
>>>>> a formal VOTE.
>>>>> 
>>>>> Please respond with one of the following:
>>>>> 
>>>>> +1: proceed with 4.1 without the Xen portion of CLOUDSTACK-2492 being
>>>>> resolved
>>>>> +0: don't care one way or the other
>>>>> -1: do *not* proceed with any further 4.1 release candidates until
>>>>> CLOUDSTACK-2492 has been fully resolved
>>>>> 
>>>>> -chip
>>>>> 
>>>>> [1] http://markmail.org/message/rw7vciq3r33biasb
>> 


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