Time synchronization between AIX machines using 'timed'.

Time synchronization between AIX machines using 'timed'.

Post by Jim Cassid » Tue, 05 Nov 1996 04:00:00



The use of 'timed' seemed simple but maybe I'm missing something.  We have
50+ sites, each with two AIX processors running 3.2.5 or 4.1.4.  I'm trying
to assure that the time is the same on both machines, so on the 'A'
processor I'm running 'timed -a -M'  which shows in the process list as
'timed -S -M'.  On the 'B' processor, we run 'timed' with no parameters and
it show in the process list as 'timed -S'.  Both these are started in the
rc.tcpip script which inittab runs.

My assumption was that this would cause the 'B' machine to synchronize it's
clock with the 'A' machine.  What the manual says is that the "timed daemon
slows the clocks of some machines and speeds up the clock on other machines
to create an average network time".  The next paragraph, however, says the
time daemon works on a master-slave relationship, that the timed daemon on
the 'B' machine will get it's time from the master 'A' machine when it
starts, and that the 'A' machine master will periodically send out
synchronization messages to the slave 'B' machine.

What I get is this ... if the 'B' machine says 9:30am, and I set the time
on the 'A' machine to 9:00am (with the timed daemons running), then both
machines will show a time of 9:15am.  I have to repeatedly set the 'A'
machine to 9:00am to get both machines to reflect 9:00am.  But, within a
day or so, the clock on both machines becomes wrong by as much as 30
minutes and needs to be reset.!?!

Can anyone tell me what I'm doing wrong here?  Am I just overlooking
something in what should be a very simple procedure?!

Thanks in advance ... Jim Cassidy

 
 
 

Time synchronization between AIX machines using 'timed'.

Post by Toralf Foerste » Wed, 06 Nov 1996 04:00:00



> The use of 'timed' seemed simple but maybe I'm missing something.  We

My experiences : the timed under AIX 3.2.5 doesn't work very well.
Use the NTP - package from http://www.ee.udel.edu/~ntp/
- and you have no problems.

toralf
--

+++ Baltic Sea Research Institute +++ Baltic Sea Research Institute +++



Toralf Foerster
INSTITUT FUER OSTSEEFORSCHUNG Warnemuende
Bereich Marine Geologie
Seestrasse 15
D-18119 Warnemuende
Germany

 
 
 

Time synchronization between AIX machines using 'timed'.

Post by Joerg Schumach » Wed, 06 Nov 1996 04:00:00


 [courtesy cc of this posting sent to cited author via email]



>[...]
>Can anyone tell me what I'm doing wrong here?  Am I just overlooking
>something in what should be a very simple procedure?!

We are using NTP, so I can't tell about timed but the last

   APAR: IX61268  COMPID: 576565500  REL: 420
   ABSTRACT: ADD TIMED OPTION TO NOT AVERAGE NETWORK TIME

   PROBLEM DESCRIPTION:
   If some of the machines on the network have bad clocks
   timed will gradually start keeping bad time.

   PROBLEM SUMMARY:
   If some of the machines on the network have bad clocks
   timed will gradually start keeping bad time.

   PROBLEM CONCLUSION:
   Add a new flag "-c" to timed that will prevent it from
   averaging the time from the systems on the network.
   It will assume that the clock of the master server is
   correct and use that for maintaining accurate time.
   By default this option is off.

To subscribe to this list:

Hope this helps,
Joerg.

 
 
 

Time synchronization between AIX machines using 'timed'.

Post by Kris Buggenho » Sat, 09 Nov 1996 04:00:00




> > The use of 'timed' seemed simple but maybe I'm missing something.  We
> My experiences : the timed under AIX 3.2.5 doesn't work very well.
> Use the NTP - package from http://www.ee.udel.edu/~ntp/
> - and you have no problems.

I second that, and you get multiplatform time synchronization in the bargain, HP-SUN-NT-SGI,etc
I have been running it for a few weeks now with an AIX box as timeserver, and worked the first time.

I recomend using xntp3.5f which is the latest stable version I could find.

Kris Buggenhout
System manager    Laboratory of medical imageing ESAT-KULEUVEN.

 
 
 

Time synchronization between AIX machines using 'timed'.

Post by desho.. » Mon, 11 Nov 1996 04:00:00



>The use of 'timed' seemed simple but maybe I'm missing something.  We have
>50+ sites, each with two AIX processors running 3.2.5 or 4.1.4.  I'm trying
>to assure that the time is the same on both machines, so on the 'A'
>processor I'm running 'timed -a -M'  which shows in the process list as
>'timed -S -M'.  On the 'B' processor, we run 'timed' with no parameters and
>it show in the process list as 'timed -S'.  Both these are started in the
>rc.tcpip script which inittab runs.

Sounds like you need to get you a synch program to call up NIST and
synch each processor to that.   Or perhaps there is something in HACMP
that can do it for you.  I don't know enough about HACMP but it was
modeled on the DEC paradigm of a cluster which in fact handles time
synch on the cluster.  The synch doesn't stay put in the DEC world
much as you have found out with multiple AIX boxes.  Of course the
processors should be within a few seconds a week, if they are not they
you need to get it fixed.  The master oscillator crystal is off
frequency, get a new one, even cheap -non stabilized crystals should
keep a machine accurace with 10 seconds a week.  PCs do that good most
of the time.  

If you want truly accurate time you have to have a master oscillator
which has an oven stabilized crystal and a regularly run program
(daily) which calculates the difference between the time base and a
comparison of a NIST cesium clock.  That is if you can't afford your
own cesium timebase.  The program would run daily and make a
correction based on the difference between the local crystal
oscillator based time and the NIST cesium clock time.  In the event of
a non-connection it would reference a database and calculate the time
shift based upon the known decay rate of the local clock, this should
put you within a few percent of correct time.  

..al..

 
 
 

Time synchronization between AIX machines using 'timed'.

Post by Colin RI » Thu, 14 Nov 1996 04:00:00




>>The use of 'timed' seemed simple but maybe I'm missing something.  We have
>>50+ sites, each with two AIX processors running 3.2.5 or 4.1.4.  I'm trying
>>to assure that the time is the same on both machines, so on the 'A'
>>processor I'm running 'timed -a -M'  which shows in the process list as
>>'timed -S -M'.  On the 'B' processor, we run 'timed' with no parameters and
>>it show in the process list as 'timed -S'.  Both these are started in the
>>rc.tcpip script which inittab runs.
>Sounds like you need to get you a synch program to call up NIST and
>synch each processor to that.   Or perhaps there is something in HACMP
>that can do it for you.  I don't know enough about HACMP but it was
>modeled on the DEC paradigm of a cluster which in fact handles time
>synch on the cluster.  The synch doesn't stay put in the DEC world
>much as you have found out with multiple AIX boxes.  Of course the
>processors should be within a few seconds a week, if they are not they
>you need to get it fixed.  The master oscillator crystal is off
>frequency, get a new one, even cheap -non stabilized crystals should
>keep a machine accurace with 10 seconds a week.  PCs do that good most
>of the time.  
>If you want truly accurate time you have to have a master oscillator
>which has an oven stabilized crystal and a regularly run program
>(daily) which calculates the difference between the time base and a
>comparison of a NIST cesium clock.  That is if you can't afford your
>own cesium timebase.  The program would run daily and make a
>correction based on the difference between the local crystal
>oscillator based time and the NIST cesium clock time.  In the event of
>a non-connection it would reference a database and calculate the time
>shift based upon the known decay rate of the local clock, this should
>put you within a few percent of correct time.  
>..al..

HACMP *won't* keep the clocks in sync - in fact it's up to the
sysadmin to do that, and if the nodes in a HA cluster get too far out
it causes problems (but I can't remember what right now!)

Of coure, timed only keeps clocks on a LAN in sync, and then only to
the average of all clocks. If you want something across the wan then
xntpd is needed (which I believe comes with AIX4.2), but it is a
* to setup.

I in fact use a script I whipped-up to use timedc to check against the
caesium atomic clock. Each host can then run this in cron nightly and
perform a nightly adjustment using the date command. You will only get
a second or so variance across all machines, but it's better than
several minutes.

The following command is the basis:-

timedc clockdiff time_a.timefreq.bldrdoc.gov

which gives milliseconds drift.

If you want the script then please mail me.

___________________________________________________
Colin Rice
Technical Team Leader
Hong Kong Convenience Stores (7-Eleven Hong Kong)

 
 
 

Time synchronization between AIX machines using 'timed'.

Post by Frank Wortne » Thu, 21 Nov 1996 04:00:00


How about trying XNTPD?

ftp://louie.udel.edu/pub/ntp/

Properly set up,  it can monitor several time sources,  and
synchronize your machine to the most "reliable" of them.  It is
somewhat more difficult to set up than timed,  but much more robust.
AIX 4.2 (I believe) supports it directly.  I've compiled and used the
version from louie.udel.edu successfully on 3.2.5 and 4.1.x.

BTW,  the US Naval Observatory operates two public access time
servers near Washinton D.C.,  tick.usno.navy.mil and
tock.usno.navy.mil.   It also sponsors other stratum 1 time servers in
various areas of the U.S.  See http://tycho.usno.navy.mil/ntp.html for
details.
--
                                        Frank

Frank Wortner, Prodigy Services Company

Opinions are solely mine, facts belong to no one in particular.

 
 
 

Time synchronization between AIX machines using 'timed'.

Post by Paul Reimol » Fri, 22 Nov 1996 04:00:00


Ditto! Why is it taking IBM do long to bundle ntp????? Other UNIX
flavors have had it for quite a while.


> How about trying XNTPD?

> ftp://louie.udel.edu/pub/ntp/

> Properly set up,  it can monitor several time sources,  and
> synchronize your machine to the most "reliable" of them.  It is
> somewhat more difficult to set up than timed,  but much more robust.
> AIX 4.2 (I believe) supports it directly.  I've compiled and used the
> version from louie.udel.edu successfully on 3.2.5 and 4.1.x.

> BTW,  the US Naval Observatory operates two public access time
> servers near Washinton D.C.,  tick.usno.navy.mil and
> tock.usno.navy.mil.   It also sponsors other stratum 1 time servers in
> various areas of the U.S.  See http://tycho.usno.navy.mil/ntp.html for
> details.
> --

--
**      Paul J. Reimold         UNIX Administrator      **      
**              General Accident Insurance              **
**      436 Walnut Street       Phila, PA  19106        **

 
 
 

Time synchronization between AIX machines using 'timed'.

Post by Valdis Kletnie » Sat, 23 Nov 1996 04:00:00




Quote:> Ditto! Why is it taking IBM do long to bundle ntp????? Other UNIX
> flavors have had it for quite a while.

Often, IBM is a bit slower to roll in 3rd party things because IBM wants
to be sure that they can *maintain* the code.  Other vendors seem to be
much more willing to "bundle and go" - about the only thing IBM does that
with is the X11 samples code, and *that* has big huge flags all over it
saying "sample code only"...

--
                                Valdis Kletnieks
                                Computer Systems Engineer
                                *ia Tech

 
 
 

1. time synchronization ('timed')

I just got my first Linux (Red Hat Intel 4.0 running on a P100)
(extremely cool).  I am connected to the net via an Ethernet card,
and I am trying to set my clock as a slave from another machine on the
net.   I found the 'timed' command, and I also saw a lot of info
related to xntp.   As I don't need super-accuracy, I thought
that using timed would be less painful (enough to keep the clock
in 'shape').   So I tried

But it didn't do any good. It gives me back:

I don't have much of a clue for what I should do to get timed
to do what I want....

 Also, I understand that I should put it somewhere to restart at every
'reboot'. Would that be 'rc.local' ????

Any help will be appreciated.

Thanks,
Carlos

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