[ntp:questions] chrony as a server

William Unruh unruh at invalid.ca
Thu Feb 19 01:53:36 UTC 2015


On 2015-02-19, Paul <tik-tok at bodosom.net> wrote:
> On Wed, Feb 18, 2015 at 6:49 AM, Charles Elliott <elliott.ch at comcast.net>
> wrote:
>
>> If you don't mind me asking, why is chrony superior to NTPD
>> for tracking a PPS signal, or even in general
>
>
> Chrony (in general) pros and cons: <
> http://chrony.tuxfamily.org/manual.html#Other-time-synchronisation-packages>

Just so people reading this know what you are saying (in the cons
package)
"Things ntpd can do that chronyd can’t:

ntpd fully supports NTP version 4 (RFC5905), including broadcast,
multicast, manycast clients / servers and the orphan mode. It also
supports extra authentication schemes based on public-key cryptography
(RFC5906). chronyd uses NTP version 3 (RFC1305), which is compatible
with version 4.
ntpd has been ported to more types of computer / operating system.
ntpd includes drivers for many reference clocks. chronyd relies on other
programs (e.g. gpsd) to access the data from the reference clocks.
"

So, if you run Windows, chrony is not for you. If you need the version 4
things again use ntpd. On the other hand if you want your system time to
be closer to UTC use chrony (in part because of the faster response of
chrony to changes like temperature changes). 

Both will discipline your clock, and work well at doing so. 


>
>
> In the specific case of PPS I don't see any advantage. 

Well, no. Lichvar did some tests with PPS and found that chrony
disciplined the clock much better than did ntpd (factors of over 10). I
think that is a difference.

>Note that Ntimed is
> intended to "fix" nearly all  the "deficiencies" (of consequence) of ntpd
> relative to chrony,

That is a promise not fact. Lets see how it works out. If it uses the same design
as ntpd, it is hard to see how it will "fix" the "deficiencies". But we
will see.



More information about the questions mailing list