I have a problem about datetime in database Oracle and OS is difference:
Database Oracle RAC version 188.8.131.52. 2 nodes rac: node1 and node2
Os: Redhat 6.3
My servers are using NTP.
when I reboot server, database was started automatically. I check time (by select sysdate) is 07:00 AM.
But in OS I check (by SQL> !date) time is 21:00 PM
Then I shutdown database and startup again. now the date in database (sysdate) and the date in OS are the same.
I don't know the reason of problem.
The date is difference only case reboot server. So the problem belong to database or OS or network?
thanks so much!
Edited by: Omni on Dec 19, 2012 12:30 AM
With Oracle Database 11g Release 2, Oracle Clusterware includes the Cluster Time Synchronization Service (CTSS).
On startup, Oracle Clusterware checks for a NTP configuration, if found, CTSS goes into Observer mode. This means it will monitor the clock synchronization and report in the Oracle Clusterware alert log if it finds a problem.
If it does not find a NTP configuration, CTSS will be active. In active mode, CTSS synchronizes all the system clocks to the first node in the cluster. The Oracle Clusterware requires the use of "-x" flag to the ntpd daemon to prevent the clock from going backwards (Linux: see /etc/sysconfig/ntpd)
Hope it helps...