I was looking to get a couple Pis and use them to feed the VMs, but we don't currently have many (any) places on our fiber plant to locate even a Pi GPS box. That'll change in the coming months, but that's not now. BTW: It seems like it's about $50 per hat to add GPS to a Pi, so we're probably looking at $100/box... not that it's prohibitive then either. ----- Mike Hammett Intelligent Computing Solutions http://www.ics-il.com Midwest Internet Exchange http://www.midwest-ix.com ----- Original Message ----- From: "Hunter Fuller" <hf0002+nanog at uah.edu> To: "Alex Balashov" <abalashov at evaristesys.com> Cc: "VoiceOps" <voiceops at voiceops.org> Sent: Monday, February 17, 2020 4:19:27 PM Subject: Re: [VoiceOps] [External] Re: [External] Re: [External] NTP Question I wouldn't call it incredibly oversubscribed, though we are getting a little close on memory these days. http://hf0002.uah.edu/sharex/chrome_nj0IR7SmQr.png We would have pursued it more, but after reading that the general wisdom was to not do it, we just stopped doing it, and things got better, and I never thought about it again until now. :) But I could see how it would be a problem in a fully virtualized environment. Maybe a Raspberry Pi with an RTC module could be an interesting low-cost/low-maintenance NTP box. Easy to have 4 of them when they're $50 per box. On Mon, Feb 17, 2020 at 4:15 PM Alex Balashov <abalashov at evaristesys.com> wrote:
Interesting. I'm thinking there's something else off there. Perhaps the hypervisor is incredibly oversubscribed?
On Mon, Feb 17, 2020 at 04:12:59PM -0600, Hunter Fuller wrote:
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/ _______________________________________________ VoiceOps mailing list VoiceOps at voiceops.org https://puck.nether.net/mailman/listinfo/voiceops
-- 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/ _______________________________________________ VoiceOps mailing list VoiceOps at voiceops.org https://puck.nether.net/mailman/listinfo/voiceops
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