NTP

[Zeeshan Zafar]

we have time synchronisation service (xntp) running on an hp database server, and it keep the time sync with time server.

I just wanted to know how often does it synchronise time with NTP server?

Many Thanks,
Zeeshan.

[BPatrick]

Hi Zeeshan,

This interval for synchronization can be configured. by default it will be either 8 or 17 minutes.
Patrick

[Zeeshan Zafar]

Where do we set this synchorinisation interval?

[Pete Randall]

Try /etc/ntp.conf or take a look at the man page for xntpd.


Pete

[BPatrick]

Zeeshan,

Check this document

http://docs.hp.com/en/B2355-90774/B2355-90774.pdf


Patrick

[Steven E. Protter]

Shalom,

Syncronization is quite frequent, at least several times an hour.

To see it work you might wish to start the ntpd service and:

tail -f /var/adm/syslog/syslog.log

Note that ntp needs port 123 open. If you have a firewall, it must permit the traffic.

SEP

[Bill Hassell · Accepted solution]

NTP is much more sophisticated than simply changing the time on a regular basis. The NTP daemon xntpd runs every 64 seconds and checks all the time servers listed in /etc/ntp.conf (note: servers, not just a single server). Once the time is accurate to within 0.128 seconds for a specific server, the time interval is increased to 128 seconds, then 512, all the way to 1024 seconds (17 minutes). If the accuracy begins to drift, it will automatically be reduced. All of this is automatic. When the time needs to be adjusted, the xntpd daemon slowly adjusts the clock speed by a few milliseconds so there is no 'jump' in time.

To see what the xntpd dameon is doing, use these two commands:

grep xntpd /var/adm/syslog/syslog.log
ntpq -p

If you see any errors in either command, NTP is not configured correctly.

[Zeeshan Zafar]

Many Thanks for all your inputs.