time drift

[perryh at pluto.rain.com]

> FreeBSD 6.2 running on X86 hardware (FSC) shows a remarkable time
> drift
>
> running ntpdate every half hour shows that the system looses about
> 10-14 sec each time.
> 15 May 10:06:48 ntpdate[7200]: step time ... offset -13.799602 sec
> 15 May 10:36:48 ntpdate[7515]: step time ... offset -12.813941 sec
> 15 May 11:06:48 ntpdate[7879]: step time ... offset -13.651921 sec
> 15 May 11:36:50 ntpdate[8079]: step time ... offset -11.109298 sec
> 15 May 12:06:50 ntpdate[8289]: step time ... offset -11.836499 sec
...
> The 6.2 system is a production system, has a uptime of almost 300
> days and I don't want to experiment a lot with acpi, battery or so. 
>
> What would be your suspicion on the large time drift of the FreeBSD
> 6.2 system?

With an uptime of nearly a year -- commendation to the power company
-- and (I take it) a recently-developed problem, I'd be asking what
might have changed shortly before the problem appeared.

Is the system clock source by any chance the CMOS RTC?  If so, I'd
suspect that its battery may be dying.