Re: How to set time difference limit between RAC nodes in 10g

From: Lu Jiang <lu.jiang69_at_yahoo.com>
Date: Tue, 18 Sep 2012 19:59:19 -0700 (PDT)
Message-ID: <1348023559.29404.YahooMailNeo_at_web125201.mail.ne1.yahoo.com>

Hi Mark,
 

I did mention it is 10g RAC database which does not have CTSS.
 

No we don't have any node evicted even when there was one node with two minutes time difference, there was no error reported in the log files. Don't know how this database was originally set up, I want to find out where I can change the time difference limit so that Oracle can reports the error and evict the node in case this happens again to pretect data integrity. Then we could get the error notification and troubleshoot the issue right away.
 

Thanks,
Lu
 

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From: "Bobak, Mark" <Mark.Bobak_at_proquest.com> To: "lu.jiang69_at_yahoo.com" <lu.jiang69_at_yahoo.com>; "oracle-l_at_freelists.org" <oracle-l_at_freelists.org> Sent: Tuesday, September 18, 2012 7:12 PM Subject: RE: How to set time difference limit between RAC nodes in 10g

You don't mention a version.  If you're on 11gR2, Clusterware includes Cluster Time Synchronization Service (CTSS).  Normally, if you're running NTP, CTSS runs in observer mode, and watches time skew and logs into log files (though I don't remember which log, off the top of my head).  If ntp isn't configured on even one of the nodes in the cluster, CTSS goes into active mode, and will manager the time difference.  Better to have NTP correctly configured, though.

So, I think the monitoring and logging you're looking for is already there, though I don't specifically recall which logfile it's in.

I'm not sure how far out of sync nodes have to get to be evicted, as I've never seen it happen.  Are you actually suffering node evictions due to this, or is this just theoretical, at the moment?

-Mark

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From: oracle-l-bounce_at_freelists.org [oracle-l-bounce_at_freelists.org] On Behalf Of Lu Jiang [lu.jiang69_at_yahoo.com] Sent: Tuesday, September 18, 2012 18:57
To: oracle-l_at_freelists.org
Subject: How to set time difference limit between RAC nodes in 10g

Hi DBA gurus,

I know we should synchronize time on all rac nodes with NTP. Time difference between RAC nodes could have impact on data integrity. It is good if we can be notified if one of the RAC node's time out of synch.

Could any one shed some lights on how to set the time difference limit on 10g rac nodes so that oracle would send error to alert log and evict the node? Did some research on this, some folks say the default value is one minute and some folks say the default value is 30 seconds. Could not find anything about this setting from Oracle documentation.

Thanks,
Lu

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Received on Tue Sep 18 2012 - 21:59:19 CDT