[OT] NTP servers - was Re: Kernel clock issue "Clocksource tsc unstable"

[Derek Broughton]

Brian McKee wrote:

> On Fri, Feb 27, 2009 at 11:22 PM, Rashkae <ubuntu at tigershaunt.com> wrote:
>> NoOp wrote:
>>
>>>
>>> I also purposely remove the ntp.ubuntu.com/canonical servers; I' don't
>>> mind providing some data, but sync'ing to them just seems a little big
>>> brother/Microsoft'ish to me.
> 
> as you wish - but I don't recall ntp sending any data the other way
> worth mentioning...

The fact that you continually connect is data.  I can see his point - though
_I_ remove ntp.ubuntu.com because I've found it notoriously hard to
reach...

>> Unless you're doing something that's extremely time sensitive (such as
>> synchronizing to those time based RSA security tokens) I don't really
>> see the point to synchronizing with ntp at all.   Any functioning clock
>> should be able to keep track of wall time within a few seconds accuracy
>> per month.
>>
> You must have better quality systems than some of mine then - I've got
> units with good batteries that wander several minutes out of whack in
> a month without ntp all the time.

A few seconds/several minutes.  Either way, it really isn't a big enough
deal to worry about, usually, but then I prefer to set my computers to
display analog clocks, because I don't like being too precise...

otoh, it seems to me that "ntp all the time" and "units with good batteries"
are conflicting criteria.  If your system is _capable_ of getting the time
via ntp, then the clock is not running on the battery.  The clock you're
seeing is the software clock, so if it's wandering while you're powered up
and not using ntp it's got nothing to do with the CMOS battery (and the hw
clock gets set from the sw clock on shutdown).  If the clock only wanders
while you're powered off, then setting the sw clock at restart time via
ntpdate would be sufficient.
-- 
derek