On 3/22/2011 1:22 PM, unruh wrote:
On 2011-03-22, David J Taylor<david-tay...@blueyonder.co.uk.invalid> wrote:
He can do that if he wants to. That was why the -q option was designed
into ntpd-- one time setting of the clock time. However it cannot create
a drift file. If he wants a drift file then as you say, he must run it
continuously.
You could look at it that way, Bill, if all he needs is a one-off setting.
However, Prashant says he wants to run it periodically, which doesn't
really make sense. Rather than a periodic run, he should leave ntpd
running continuously, which is what ntpd is designed for.
ntpd -q is a replacemtn for ntpdate, which was typically run from cron,
and he is doing, and it is an "acceptable" procedure if for example you
do not want a daemon running which could have (unknown to you) security
issues. It is also a bit unclear how to switch off the server role of
ntpd and he may not want others querying his machine. On the other had
it comes at a cost of far worse clock discipline and the probability of
the computer jumping backwards in time.
Prashant, the fact that the server capability is already built-in to ntpd
in no way detracts from using ntpd just as a client for your PC to keep
the time spot-on. Just leave it running all the time as it uses very
little resources. It will then compute the drift information after (IIRC)
one hours of running, and it will keep your PC clock correct by adjusting
the rate, rather than bang-bang adjustments of the time.
One hour? More like 10 hr. ntpd is really bad at recovering from
changes, and switchon is a big change.
After 1 hr the drift is liable to be way off, as ntpd alters the drift
to bring the clock back into line.
That depends on how accurate you want your time to be. NTPD should have
the right day, hour, and minute within a very few minutes or even
seconds. If you want microsecond accuracy you run in a temperature
controlled environment and endeavor to keep it running 24 hours a day,
seven days a week, 365 days a year!
There are people who want fast startup. NTPD does not do fast startups.
If you want to turn everything on at 8:30AM and shut it all off again at
5:00PM, NTPD is not good choice!!
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