[VoiceOps] [External] Re: [External] NTP Question
hf0002+nanog at uah.edu
Mon Feb 17 17:12:59 EST 2020
I wouldn't say we need it to be "really precise," but we do need it
within a couple of seconds, and on ESXi 6 we were seeing boxes as far
as 500ms off. It may not apply to all VM environments, so I guess it
could be worth testing. But it certainly scared me off. With physical
NTP servers we achieve within 10ms generally.
On Mon, Feb 17, 2020 at 4:09 PM Alex Balashov <abalashov at evaristesys.com> wrote:
> On Mon, Feb 17, 2020 at 04:00:25PM -0600, Hunter Fuller wrote:
> > On Mon, Feb 17, 2020 at 3:57 PM Mike Hammett <voiceops at ics-il.net>
> > wrote:
> > > Is having four VMs running NTP a ridiculous proposition (well, other
> > > than resources, which it'll consume very little)?
> > Yes. NTP servers should never run in VMs.
> I don't know about that. The nature of virtualisation has changed
> greatly over the past decade; VMs have gone from being a kludgy and slow
> software-emulated environment to almost a first-class CPU guest, thanks
> to paravirtualisation and supporting CPU features.
> And NTP is specifically designed for latency in a rather general sense.
> If you're using NTP for any really precise timing calibration, that's
> the wrong vehicle, anyway.
> -- Alex
> Alex Balashov | Principal | Evariste Systems LLC
> Tel: +1-706-510-6800 / +1-800-250-5920 (toll-free)
> Web: http://www.evaristesys.com/, http://www.csrpswitch.com/
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