Oracle 11g RAC, internal time is synchronized through the ctss service, during installation, ntpd will be removed by default, using ctss.
However, after running for a period of time, it is found that there is a time difference between the oracle internal time and the operating system. Therefore, the oracle database and the operating system need a time synchronization server;
/Sbin/service ntpd status
Ntpd (pid 4403) is running...
Ps-ef | grep ntp
Ntp 2113 1 0 Dec09? At 00:00:00 ntpd-u ntp: ntp-p/var/run/ntpd. pid-x
Grep OPTIONS/etc/sysconfig/ntpd
OPTIONS = "-u ntp: ntp-p/var/run/ntpd. pid-x"
To start:
/Sbin/service ntpd start
[Grid @ rac01 ~] $ Crsctl check ctss
The CRS-4701: The Cluster Time Synchronization Service is in Active mode.
CRS-4702: Offset (in msec): 0
When the ctss detects that there is ntp on the system, it automatically switches the mode to the passive mode.
[Grid @ HBCADB001 ~] $ Crsctl check ctss
The CRS-4700: The Cluster Time Synchronization Service is in Observer mode.
SQL> select sessiontimezone, to_char (sysdate, 'yyyymmdd hh24: mi: ss') from dual;
SESSIONTIMEZONE
---------------------------------------------------------------------------
TO_CHAR (SYSDATE ,'
-----------------
+ 08:00
14:14:10 20121029
SQL>! Date
Mon Oct 29 14:14:13 CST 2012
SQL>