[ntp:questions] Re: [VMS] config or clock?

Danny Mayer mayer at gis.net
Tue Feb 3 01:20:09 UTC 2004


"Richard B. Gilbert" <rgilbert88 at comcast.net> wrote in message news:<doWdnegTz-L1CIHdRVn-gQ at comcast.com>...
> I'm afraid your local clock is beyond any help that NTP can provide!  
> 500ppm is the maximum that NTP can cope with and you are there or beyond.
> 
> It may be possible to fix the clock by patching the O/S to give the 
> clock a permanent "slew" that will cause it to tick every 10ms within, 
> say, 100ppm..  I'd suggest inquiring on comp.os.vms if this is 
> feasible.  I know that in past years, there were programs that would 
> allow you to make the change between standard and daylight time by 
> running the clock faster in the spring and slower in the fall  for a 
> period of an hour or two.  This was for people who, for one reason or 
> another, could not simply jump the clock forward or backward by an 
> hour.  With more modern versions of VMS far fewer people have need of 
> this software; since VMS V7.0 (I think!) VMS has kept UTC internally and 
> simply displayed local time as required.
> 
Someone at DEC (okay HP now) seems to have taken an interest in porting
the latest ntp 4.2.0 code to VMS (see bug $275). Maybe that sometime in
the near future you will see a new version of ntp available on VMS from
the VMS people.

Danny
> It may also be possible to fix the hardware to bring the 10ms tick 
> within spec.   I'm running  NTP on six Alphas  with VMS V6.2-1H3 with 
> UCX 4.2 ECO 5 or VMS V7.2-1 with TCPIP V5.1 ECO 4 and not seeing a 
> problem with any of them.  Depending on the quality of the time supplied 
> by servers, they all manage to synch within 10ms and usually less than that.
> 
> Alder wrote:
> 
> > I've just started paying some attention to the system time on my 
> > AlphaServer 1000A 4/266.  It's running VMS 7.3 and TCP/IP Services 5.4.
> >
> > After visiting www.ntp.org and perusing the docs, I tested the 
> > stability and accuracy of my system clock by stopping the NTP service 
> > and setting my clock with ntpdate against the 'closest' time server to 
> > me.  I found this:
> >
> > $ ntpdate "-o" 4 "-p" 4 ntp.cpsc.ucalgary.ca
> > Selected server is ntp.cpsc.ucalgary.ca (136.159.2.3) offset +0.4557905
> >
> > ... 8 hours later:
> >
> > $ ntpdate "-o" 4 "-p" 4 ntp.cpsc.ucalgary.ca
> > Selected server is ntp.cpsc.ucalgary.ca (136.159.2.3) offset +34.9372245
> >
> > That looked to me like my clock was losing time rapidly.  I then 
> > started the NTP service and monitored the drift and log files for 
> > awhile.  THe drift file moved from a value of 0.0 at service startup 
> > to 500.0 within an hour or two.
> >
> > My log file over this period showed an ever increasing 'slew' value as 
> > NTP tried correcting my clock:
> >
> > $ search tcpip$ntp_run.log "time slew"
> > 31 Jan 09:44:58 ntp[216]: time slew 0.390476 s
> > 31 Jan 09:58:53 ntp[216]: time slew 1.085532 s
> > 31 Jan 10:18:18 ntp[216]: time slew 1.682264 s
> > 31 Jan 10:36:10 ntp[216]: time slew 2.123613 s
> > 31 Jan 10:52:20 ntp[216]: time slew 2.604056 s
> > 31 Jan 11:07:54 ntp[216]: time slew 3.144392 s
> > 31 Jan 11:31:09 ntp[216]: time slew 3.654378 s
> > . . .
> > 31 Jan 15:48:20 ntp[216]: time slew 14.203758 s
> > $
> >
> > My config file is pretty basic, so I'm wondering if the 'symptoms' I 
> > reported above are a function of my clock, or are they the result of 
> > bad configuration?
> >
> > $ type tcpip$ntp.conf
> > driftfile SYS$SPECIFIC:[TCPIP$NTP]TCPIP$NTP.DRIFT
> > server time.nrc.ca version 4
> > server ntp1.cmc.ec.gc.ca version 4
> > server tick.utoronto.ca version 3
> > server time.chu.nrc.ca version 3
> > server ntp.cpsc.ucalgary.ca version 4
> > server timelord.uregina.ca version 3
> > statistics loopstats
> > statsdir SYS$SPECIFIC:[TCPIP$NTP.STATS]
> > $
> >
> > Any help most appreciated...!
> >
> > Terry
> >



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