On 7/1/12, PC <paul4...@gmail.com> wrote: > If your application requires sub-5 second accuracy, (such as end of a > banking day), then Windows NTP is unsuitable for the purpose. Looks like CYA on Microsoft's part.
That i've seen, Windows NTP in physical environments with a hardware system clock not having issues consistently provides accuracy better than +/- 0.5 against the time source it's synced with, but in virtual environments, which have incompatibilities with high sub-second RTC accuracy in the first place, neither Windows nor Unix NTP services are able to provide that consistently without much tinkering. If it's absolutely critical that you have sub-5 second accuracy, even Unix NTP is not to be considered good enough, you need highly accurate hardware time source, something more accurate than the usual system clock you find in a PC or server. Unix NTP can only do so much to correct for a broken system clock; although it does do a very good job disciplining PC real-time clocks that consistently run a bit too fast or too slow, ultimately the personal computer clocks can at times be unreliable.... If they were perfect, you wouldn't need time sync in the first place; just set them once, and correct the annual 0.01 seconds worth of error once a year.... -- -JH
