On Tue, Mar 25, 2014 at 5:36 AM, <[email protected]> wrote: > It depends if you use container or full virtual hosts. With typical VPS you > have a shared kernel and you are not allowed to set the hardware clock or > the kernel clock from inside the container. If the host you are running on > is synced with ntp this doesn't matter and ntp happily distributes the host > time. The downside is that ntpd run as root in this case because it don't > get the sys_time capability. If you use full virtualisation you are on the > trouble side because the virtual system think it is able to access the clock > alone but the hypervisor actually only create a virtual clock with ever > changing precision.
The container case was probably typical a few years ago, but the current state-of-the-art is paravirtualized hypervisors. Each instance has its own kernel and "sees" the hardware clocks directly. The wall time is only fetched from the host on boot[1]. With such a VPS, I end up with a lower error than any of my "real" hardware at home, presumably due to higher-quality parts and better temperature sensitivity. Throw in really good Internet connectivity and it's a fine NTP server. -rt [1] Indeed, if one doesn't run ntpd on such an instance, the clock will drift. -- Ryan Tucker <[email protected]> _______________________________________________ pool mailing list [email protected] http://lists.ntp.org/listinfo/pool
