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From John Burwell <jburw...@basho.com>
Subject Re: [DISCUSS] How to best do time sync. (WAS: [VOTE] Release Apache CloudStack 4.1.0 (fifth round))
Date Thu, 30 May 2013 18:42:21 GMT
Ilya and Chip,

I stand duly corrected. Sorry for diverting the conversation.

-John

On May 30, 2013, at 2:22 PM, "Musayev, Ilya" <imusayev@webmd.net> wrote:

> I forgot to mention, with option 1, you should have the least issues regardless of what
hypervisor technology you use - even if you go with HyperV :)
>
> And I think Chiradeep is right, it should be Zone based, since this is when SSVM and
CPVM gets created.
>
>> -----Original Message-----
>> From: Musayev, Ilya [mailto:imusayev@webmd.net]
>> Sent: Thursday, May 30, 2013 2:14 PM
>> To: dev@cloudstack.apache.org
>> Subject: RE: [DISCUSS] How to best do time sync. (WAS: [VOTE] Release
>> Apache CloudStack 4.1.0 (fifth round))
>>
>> John,
>>
>> For vmware, you have 2 options, clock sync will work with native NTP
>> daemon using local ntp servers in your datacenter or use vmware tools
>> native time keeping technique.
>>
>> We have over 2500 VMs, and while we have vmware tools installed on all
>> vms, we choose to use native linux NTPD for time sync VS vmware
>> hypervisor provided time sync. In past, vmware tools time sync was buggy
>> and not recommended, so we decided to keep it simple and make use of
>> existing ntp servers. As of now, inherent issues maybe, if you go through
>> major upgrade of Vsphere, if you change vmware hardware version, if you
>> don't update the tools - you have 3 places where time keeping may break
>> (though I hope vmware dev team consider all that - it is still a possibility)
>>
>> I propose we make this optional when cluster is configured.
>>
>> For example,  we have a check box that says
>> 1) use local NTP servers for time keeping (if selected)
>>    NTP SERVER1
>>    NTP SERVER2
>> 2) use native hypervisor vm tools for time sync (be it vmware,kvm, xen or
>> whatever else it may be)
>>
>> We let user make his own decision on how to go about this issue, and user
>> would know best what's applicable for his environment VS us, making
>> decisions on their behalf.
>>
>> For vmware, we have have to submit 3 more arguments into "vm.details"
>> attribute with an option for timesync=vmtools ot timesync=ntp
>>    If timesync=ntp, get values of ntpserver1 and ntpserver2, configure
>> local ntp.conf file to use with native linux ntpd daemon
>>    If timesync=tools, use vm tools provided time keeping technique
>>
>> Feedback is welcome,
>>
>> Thanks
>> -ilya
>>
>>
>>> -----Original Message-----
>>> From: John Burwell [mailto:jburwell@basho.com]
>>> Sent: Thursday, May 30, 2013 1:44 PM
>>> To: dev@cloudstack.apache.org
>>> Subject: Re: [DISCUSS] How to best do time sync. (WAS: [VOTE] Release
>>> Apache CloudStack 4.1.0 (fifth round))
>>>
>>> IIya,
>>>
>>> I can't speak to KVM, but on VMWare, clock sync won't work without tools.
>>> It's not an option.
>>>
>>> Thanks,
>>> -John
>>>
>>>
>>> On Thu, May 30, 2013 at 1:30 PM, Musayev, Ilya <imusayev@webmd.net>
>>> wrote:
>>>
>>>> I'd say Cluster setting.
>>>>
>>>> We should let users pick if they want to use hypervisor tools based
>>>> sync or local/external NTP servers.
>>>>
>>>> I'm all for local/external NTP servers, as I know how those never
>>>> gave me issues in past (especially when you go through hypervisors
>>>> upgrades and vm tools upgrades).
>>>>
>>>>
>>>>
>>>>> -----Original Message-----
>>>>> From: John Burwell [mailto:jburwell@basho.com]
>>>>> Sent: Thursday, May 30, 2013 1:02 PM
>>>>> To: dev@cloudstack.apache.org
>>>>> Subject: Re: [DISCUSS] How to best do time sync. (WAS: [VOTE]
>>>>> Release Apache CloudStack 4.1.0 (fifth round))
>>>>>
>>>>> Ilya,
>>>>>
>>>>> One very important note is that NTP is only used for Xen.  For KVM
>>>>> and VMWare, time sync is accomplished through kernel
>>>>> drivers/system daemons with NTP configured in the hypervisor
>> configuration.
>>>>> Therefore, this
>>>> model
>>>>> would need to be conditional based on the hypervisor type --
>>>>> possibly a cluster-level setting?
>>>>>
>>>>> Thanks,
>>>>> -John
>>>>>
>>>>> On May 30, 2013, at 12:58 PM, "Musayev, Ilya"
>> <imusayev@webmd.net>
>>>>> wrote:
>>>>>
>>>>>> Thanks Chip.
>>>>>>
>>>>>> I've posted this response under CLOUDSTACK-2492.. curious what
>>>>>> others
>>>>> may think about a long term solution to this problem..
>>>>>>
>>>>>> --------------
>>>>>> I think we should make the whole NTP schema more modular and
>>> robust.
>>>>>>
>>>>>> For example, in my experience working for several companies, not
>>>>>> even once have we used vmware tools time sync - due to known
>>>>>> bugs and issues. Instead we would prefer to use local NTP server
>>>>>> or external pool.ntp.org
>>>>>>
>>>>>> There are two way we can address this:
>>>>>>
>>>>>> Quick solution (quick means not ideal):
>>>>>> Capture the NTP servers defined on MS and feed it as arguments
>>>>>> to system vms On initial start of the system vm, check if you
>>>>>> can access ntp servers defined on MS vm, if not, check if you
>>>>>> can access pool.ntp.org servers - if none defined - use
>>>>>> hypervisor tools sync
>>>>>>
>>>>>> Long term solution:
>>>>>> When adding zones, define NTP servers in UI to be used with
>>>>>> system VMs
>>>>> or bypass NTP servers and allow vm-tools time sync with hypervisor.
>>>>>>
>>>>>> Thoughts?
>>>>>>
>>>>>> Thanks
>>>>>> ilya
>>>>>>
>>>>>>> -----Original Message-----
>>>>>>> From: Chip Childers [mailto:chip.childers@sungard.com]
>>>>>>> Sent: Wednesday, May 29, 2013 2:30 PM
>>>>>>> To: dev@cloudstack.apache.org
>>>>>>> Subject: [DISCUSS] How to best do time sync. (WAS: [VOTE]
>>>>>>> Release Apache CloudStack 4.1.0 (fifth round))
>>>>>>>
>>>>>>> Ilya,
>>>>>>>
>>>>>>> I'm breaking off a new thread for this discussion.  If you want
>>>>>>> to discuss the design options presented in the jira, this would
>>>>>>> be a good thread for that. ;-)
>>>>>>>
>>>>>>> -chip
>>>>>>>
>>>>>>> On Wed, May 29, 2013 at 06:24:27PM +0000, Musayev, Ilya wrote:
>>>>>>>> John,
>>>>>>>>
>>>>>>>> I clearly see your concern, please review my response under
>>>>>>>> CLOUDSTACK-
>>>>>>> 2492.
>>>>>>>>
>>>>>>>> Thanks
>>>>>>>> ilya
>>>>>>>>
>>>>>>>>> -----Original Message-----
>>>>>>>>> From: John Burwell [mailto:jburwell@basho.com]
>>>>>>>>> Sent: Wednesday, May 29, 2013 10:10 AM
>>>>>>>>> To: dev@cloudstack.apache.org
>>>>>>>>> Subject: Re: [VOTE] Release Apache CloudStack 4.1.0 (fifth
>>>>>>>>> round)
>>>>>>>>>
>>>>>>>>> -0.  I don't believe we should be shipping a release
with
>>>>>>>>> known clock sync issues (see CLOUDSTACK-
>>>>>>>>> 2492<https://issues.apache.org/jira/browse/CLOUDSTACK-
>> 2492>).
>>>>>>>>> Since the community voted to go forward, I will not cast
a -1.
>>>>>>>>> However, I feel it is important to highlight operational
>>>>>>>>> issues that, in my view, a system such as CloudStack
should
>>>>>>>>> never knowingly
>>>>>>> ship.
>>>>>>>>>
>>>>>>>>> -John
>
>

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