[ntp:questions] NTP under AIX?
terje.mathisen at tmsw.no
Tue May 16 17:27:01 UTC 2017
William Unruh wrote:
> On 2017-05-16, David Woolley <david at ex.djwhome.demon.invalid> wrote:
>> On 16/05/17 16:37, Greg Moeller wrote:
>>> Has anyone come across the advisability of running an
>>> enterprise-wide NTP server under an AIX LPAR? We're currently
>>> running NTP on old Intel hardware and the company policy is to
>>> refresh hardware on a regular basis. It seems a waste to buy
>>> several new servers if we could just put the NTP service on an
>>> AIX LPAR.
>> If you are talking virtual machines, ntpd should always be run on
>> the host. Any use on a guest should only be as a leaf node.
> Remember also that you could put the ntp server onto some old or
> small hardware (eg a Raspberry Pi connected to a GPS with a PPS
> output). These is not necessity to run it on large fast expensive
> hardware. Also you want to run it on something whose workload does
> not fluctuate since work requires energy which produces heat, and the
> biggest enemy of accurate clocks is fluctuating temperature of the
> clock crystal. The actual value of the temperature does not really
> matter, but the fluctuations do.
> But as David says, you should never try to run an ntp server on a
> virtual machine. Far too much bad interaction between the virtual OS
> and the actual hardware, which is what ntp is trying to control.
> Of course it depends on the accuracy you want. If +-1sec is good
> enough then almost anything you do will work. If you want +- 1
> microseconds, you will have to work at it and virtual machines will
> be a disaster. If you want 1ns, then you will need special hardware.
3-4 reference servers based on old PC hardware running FreeBSD or maybe
linux can be setup for extremely close to zero cost, add $40-100 for
timing GPS receivers and Bob's your uncle.
- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"
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