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RE: RAC time clocks (sysdate)

From: Jesse, Rich <>
Date: Thu, 10 Jul 2003 13:25:52 -0700
Message-ID: <>

Hey Matt!

I thought that it was a bit of proper manners to avoid hitting the public stratum-1 servers unless you were planning on being a public stratum-2, just to avoid overloading the stratum-1s.


Rich Jesse
System/Database Administrator

Quad/Tech Inc.
A Subsidiary of Quad/Graphics

Sussex, Wisconsin USA
414-566-7633 phone

-----Original Message-----
Sent: Thursday, July 10, 2003 3:29 PM
To: Multiple recipients of list ORACLE-L

Beware, NTP can be a complicated critter to get working in a proper fashion. The best way to configure your NTP is to have one or two local stratum 2 or stratum 3 servers that all of your nodes sync off of (a good choice for these servers are servers that do other low-load internal services like mail relay or DNS). Those servers should each be configured with two unique stratum 1 or 2 servers and then set up to peer off of each other. Then, point your database servers at your stratum 2 servers. If your servers are too far out of sync with the rest of the world, NTP won't change the clocks instantaneously, but will gradually "drift" your clocks into sync. If you want to rush the process, stop the ntpd process, use ntpdate to set the clock one time, and then restart ntp. The drift should be small enough that will immediately maintain synchronization.  

The above config is a little bit over-engineered if you only have a few hosts, but if you don't already have a global time management system configured, now is the time (no pun intended) to do it - its one of those things that should be required for any infrastructure. Properly synchronized time makes things like auditing, monitoring, and general sanity an order of magnitude easier. The above system will easily scale to up to a few hundred hosts and basically insures that the time will be consistent across the infrastructure as a whole. The other nice thing about NTP is that its an interesting protocol, for those who care about such things, since it actually makes a distinct effort to take network latency and so-such into consideration when setting the time.  


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Author: Jesse, Rich

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