[ntp:questions] running NTP as server only

Rob nomail at example.com
Thu Aug 19 16:20:28 UTC 2010

Maarten Wiltink <maarten at kittensandcats.net> wrote:
> "Rob" <nomail at example.com> wrote in message
> news:slrni6q3i8.ie0.nomail at xs8.xs4all.nl...
>> unruh <unruh at wormhole.physics.ubc.ca> wrote:
>>> On 2010-08-19, Rob <nomail at example.com> wrote:
>>>> unruh <unruh at wormhole.physics.ubc.ca> wrote:
>>>>> On 2010-08-17, folkert <folkert at vanheusden.com> wrote:
>>>>>> Is it possible to run the NTP daemon only as a server and not as a
>>>>>> local-clock maintainer?
>>>>>> Reason: I have a virtual machine which gets its time via the vmware
>>>>>> tooling from the hardware server it is running on. Now this virtual
>>>>>> machine needs to distribute the time to clients.
>>>>> Aarrgdaagh. Why would you have a virtual machine, with its
>>>>> remarkably unreliabl e clock serve its time to others?
>>>> Some companies are virtualizing all their hardware.
>>>> E.g. this is happening where I work as well.  All the servers have
>>>> been replaced by a number of Vmware ESX machines.
>>>> So there is no physical hardware machine left to run as the ntp
>>>> server.
>>> uh, to quote Landauer, all information is physical. All virtual
>>> machines MUST also run on physical machines.
>> But that does not mean you can run NTP on them.
>> E.g. on VMware ESX, you cannot do this.
>> (there is an NTP running on the console session, but that is just a
>> virtual machine running a Linux variant, it is not running on the
>> physical machine either)
> And not so long ago, somebody quoted a more recent whitepaper here
> that said running NTP in the virtual machines was now working much
> better and in fact recommended.

You misread my statement, which was probably not very clear.

With "But that does not mean you can run NTP on them" I meant to say
that you cannot run NTP on the physical machine.  In VMware ESX, you
cannot run user processes on the physical machine.  The NTP that is
running on ESX (in the console session) is running in a virtual machine.

And yes, they do recommend (and it works OK in my experience) to run
NTP in all your virtual machines to keep their time synchronized.
(as opposed to using the "old" method of synchronizing the virtual
machine time to the host time, a setting in VMware tools)

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