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тАО06-01-2009 07:26 AM
тАО06-01-2009 07:26 AM
NTP and a financial system
I believe the step command would do the trick, but I have never used this option and can't afford to bring down the system based on a guess how this command works.
In the ntp.conf file would I add the line :
step 0.100
to have the system adjust by 1/10th of a second at a time till the time is caught up? And what is the interval for the adjustment?
thanks for the help, still new to unix and getting used to it's touchiness.
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тАО06-01-2009 07:49 AM
тАО06-01-2009 07:49 AM
Re: NTP and a financial system
ntp will not adjust a system that is off by more than a few hours.
It will not bring down a system at the standard default ntp.conf configuration if there is a small time difference.
Oracle doesn't like backward time adjustments but ntp will merely run the clock slowly if an adjustment back is required.
I would leave ntp.conf alone in this matter. The adjustment rate will not crash any applications.
SEP
Owner of ISN Corporation
http://isnamerica.com
http://hpuxconsulting.com
Sponsor: http://hpux.ws
Twitter: http://twitter.com/hpuxlinux
Founder http://newdatacloud.com
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тАО06-01-2009 08:47 AM
тАО06-01-2009 08:47 AM
Re: NTP and a financial system
If the time difference is less than 10 minutes, there is nothing to do. After a few hours, the time will be in sync with the new server. The step option in ntp.conf is virtually never used and if used, requires extensive understanding of the NTP protocol and calculations.
Bill Hassell, sysadmin
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тАО06-01-2009 08:51 AM
тАО06-01-2009 08:51 AM
Re: NTP and a financial system
The system we use has many databases that are spread across 20 different HP-UX servers that require the time be synch'd across the board to ensure reliable financial transactions.
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тАО06-01-2009 09:03 AM
тАО06-01-2009 09:03 AM
Re: NTP and a financial system
Who's horse and who's cart here when you say, "to ensure the new time server will not cause a problem with my financial systems clock"?
In my opinion, you need to establish your internal time server to synchronize with at least three external sources. You can easily use sources from the NTP POOL at:
http://www.pool.ntp.org/
Then, for each of your servers, configure NTP in each '/etc/rc.config.d/netdaemons' to point to this time source:
export NTPDATE_SERVER=mytimeserver.xyz.com
export XNTPD=1
export XNTPD_ARGS=-x
Begin by establishing your new internal time server and get it correctly synchronized to the correct time.
Then, server-by-server, plan a reboot or a quiesced period where you can manually adjust the server's time _before_ enabling synchronization to the new server.
Regards!
...JRF...
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тАО06-01-2009 03:36 PM
тАО06-01-2009 03:36 PM
Re: NTP and a financial system
Did you mean to say that you changed the NTP server's clock? With only one server, that should never be done without a complete shutdown of all the applications on all the systems that use this clock. That's why James suggests never to use a single NTP server. Most modern routers have NTP capability built in and use multiple servers on the Internet to provide extreme accuracy (less than 1/10 sec accuracy).
If you meant to say that the new time server was off by 2 minutes from the old time server, there are a lot of concerns. First, the new server should have been synced to the old server. Once the new server is within one second of accuracy (check with ntpq -p), change all your servers thatt refer to the old server to add the new server to ntp.conf (don't use the "prefer" option). Then after a few hours (or days), turn off the old NTP server. All the client systems will keep in step with the new server with no loss of sync.
If you meant to say that your server was 2 minutes behind, then how did you start xntpd? If you used the start/stop script called xntpd, then that was the prblem. This cript should only be run at bootup. The reason is that during startup, the clock is jumped to the right time long before any applications are run. The first thing the xntpd script does is to call ntpdate which forces an instant change of the current time.
Bill Hassell, sysadmin