[BBLISA] ntp question

[Dewey Sasser]

Edward Ned Harvey wrote:
> Instead, I use cron to schedule ntpdate once per hour on every machine.  It
> may be less precise (because the clock is allowed to drift, and only gets
> corrected once per hour) but it's a whole lot more reliable.  How far off
> does the clock drift over the course of an hour?  Typically, I'd say a
> second.  Maybe five seconds if you're really pushing it.  I don't care about
> that for any purposes in my infrastructure.  I care about the reliability
> more.
>   
(Note:  I'm the de facto admin for the network Eric is talking about.)

That's a good point, and I've actually tried that methodology on a host
of systems.  One problem I've encountered is that many of our "systems"
are actually VMWare based virtual machines and VMWare seems to have a
borderline ridiculously bad clock drift.  From what I've read on the
'net (which, as we all know, is always true) this can somehow manifest
as either lead as well as lag.

I have observed some of our virtual machines which were synchronized
hourly with ntpdate to drift several minutes apart over the course of
their hour.  This seems to have made e.g. NFS very unhappy.

--
Dewey