[ntp:questions] NTP under AIX?

William Unruh unruh at invalid.ca
Tue May 16 20:32:45 UTC 2017

On 2017-05-16, Greg Moeller <skywise at gmail.com> wrote:
>> My semi costs $1000000 and does very heavy hauling. What do you mean I
>> cannot enter it into the Indie 500?
They would not allow me to do so.

> Of course you can.  Will it do very well in the race?  Possibly not.  But it wouldn't have to pit so maybe it could be a tortoise/hare thing.  :)
> You can also haul a load of merchandise to a warehouse with a panel truck or a pickup truck.  Is it very good at it?  Probably not. 
> Is the IBM P series hardware very good at multitasking?  Yes, yes it is.  (that's what it's main/only job is)

Precisely. It would not be very good at it. 

>> >
>> > Is there a way to test?  It seems like I'm heading into the unknown here.  :)
>> No. It is not unkown. It is well known. It is a bad idea.
> Technically, running NTP on unix isn't a very good idea as all unix systems are multitasking and can get busy/lose time.  I suppose the question is how sloppy any given system might be.

The cpu has a cycle counter in it. That counter does not care that the

system is multitasking. Ie the time counting is not a software clock.  

Can one put a ntp onto a virtual machine. Yes. Does it give great time?

> A nice oven-controlled-crystal dedicated system running a dedicated OS just for time keeping would serve the best time.

Yes. But again it depends on its time source. Using a gps receiver with
a PPS output will give time to a few microseconds of UTC. If you are
serious about time for your systems, get a gps. You can run a coax out
to a window somewhere where you put the gps antenna. A hundred feet of
coax should get you out to window-- preferably facing south with a
realtively clear viewof the sky.  If needed you can
compensate for the time delay along that cable ( about 1.5ns per foot if
you require that accuracy-- you still have not told us what accuracy
you want. ).

Re your people-- don't call it a computer. Call it an ntp time source.
Make a nice box for it if nessary and still come in well under the spare
change limit in your organization.

But yes, a nice oven controlled crystal dedicated system would serve
time best. You can buy them. Of course the time that the computers in
your organization got from it would be much less accurate, and probably
no worse than if youuse an RPi with a Sure GPS receiver (about $80-- 100
with box).

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