topic Re: TIME SYNCHRONISATION ATOMIC CLOCK in Operating System - HP-UX

TIME SYNCHRONISATION ATOMIC CLOCK

Luk Vandenbussche — Thu, 10 Oct 2002 05:22:04 GMT

Hello,

I want to synchronise the clock op my HP9000 model L1000 (HPUX 11.00) with an external atomic clock. Where can I find such an external HPUX supported module. I don't have internet access with my server, and I keep it that way.

Thx

Re: TIME SYNCHRONISATION ATOMIC CLOCK

Frederic Sevestre — Thu, 10 Oct 2002 05:42:45 GMT

Hi Luk,

Have a look there :

http://www.meinberg.de/english/info/ntp.htm

The most often DCF77 receiver used is the DCF77C51
http://www.meinberg.de/english/products/c51.htm

For GPS, customers often use
http://www.meinberg.de/english/products/gpskmpl.htm

http://www.gudeads.com/

Regards,
Fr??d??ric

Re: TIME SYNCHRONISATION ATOMIC CLOCK

Cheryl Griffin — Thu, 10 Oct 2002 14:24:26 GMT

This is Network Time Protocol (NTP). If you cannot sync this particular machine to the Internet, maybe you can sync it to another machine that does have access to the Internet.

Installing and Administering Internet Services
Chapter 7 Configuring the Network Time Protocol

http://www.docs.hp.com/cgi-bin/fsearch/framedisplay?top=/hpux/onlinedocs/B2355-90685/B2355-90685_top.html&con=/hpux/onlinedocs/B2355-90685/00/00/63-con.html&toc=/hpux/onlinedocs/B2355-90685/00/00/63-toc.html&searchterms=ntp&queryid=20021010-092649

Cheryl

Re: TIME SYNCHRONISATION ATOMIC CLOCK

John Poff — Thu, 10 Oct 2002 14:34:43 GMT

Hi,

To follow up on Cheryl's point, if you can't get Internet access with any of your systems, you can pick one to be the time server, keep the time set on it manually, and use it to serve ntp to the other systems.

JP

Re: TIME SYNCHRONISATION ATOMIC CLOCK

Brian Kinney — Fri, 11 Oct 2002 13:07:34 GMT

First, choose a source for your time clock.

a) Intelligent clock which hooks onto your NETWORK ($1,500 US for GPS version).

b) Dumb clock which hooks into your computer.
(About $700 US.)

I personally would vote for option A, as you don't have to reconfigure a "production server" to communicate with a slave device.

The GPS version is my choice of tools, as it won't be affected by weather patterns. (WWVB is affected by it.)

Option A: Buy the clock, hook up the tiny GPS antenna, connect it to the local lan, arp to it and set its IP address and so on.

Option B: Buy the clock, hook up your antenna, connect the clock to a serial port. Next, run SAM on the dedicated host to choose which radio device you purchased (yes, some are "in the box.") and reference the appropriate serial port. Start NTP up, and your local server now has the correct time.

For BOTH OPTIONS,then on every HP host in your LAN, use SAM and adjust the time settings to use that server's IP address as a time server, ask it to start NTP, and you are done. (thanks SAM!)

Pitfalls:
Only really big one is the 1,000 seconds off problem. NTP "stops running" if your local clock is off by more than 1,000 seconds. As root, run:

ntpdate

This SHOULD force the local machine to the correct time. Now start NTP back up and you're in business.

This is definitely a glossed over version of what to do....

Brian

Re: TIME SYNCHRONISATION ATOMIC CLOCK

Bill Hassell — Fri, 11 Oct 2002 18:30:34 GMT

Yikes, don't run ntpdate to correct the time of day on a running system! The reason NTP won't try to sync up is that it would take hours and hours to slowly slew the clock to the correct time...and if you have only one NTP server, there might be something wrong. NTP is very paranoid about accuracy and trusts very little that is too far off. Using ntpdate (or simply changing the time with the date command) is a good way to corrupt databases and confuse cron jobs.

The best way to setup NTP on HP-UX is to enable it with SAM, point to the time server's IP address and then use ntpq -p IP-addr to see if it responds. Once SAM has enabled NTP, see if the current time is within a few seconds of being accurate. If so, let it cook for a few hours and check syslog for any NTP errors.

To correct a big time error, shutdown and reboot. That way, the databases and other time-sensitive programs will never see the jump.

Re: TIME SYNCHRONISATION ATOMIC CLOCK

Luk Vandenbussche — Thu, 15 Sep 2005 01:24:30 GMT

problem solved