Wednesday, August 17, 2011

Oracle 11g Release 2: CTSS and NTP Service

CTSS daemon service is a new service introduced in Oracle 11g Release 2 for the time synchronization between the nodes. As I have mentioned earlier few of the details about it in Oracle 11g Rel 2 New Features it is a replacement of NTP service.

CTSS runs in 2 ways:
  • Observer mode: whenever NTP is installed on the system, CTSS only observes

  • Active mode: time in cluster is synchronized against the CTSS master (node)

CTSS daemon tags first node started in the cluster as the master time manager. In any case, if NTP service is not available then other CTSS daemons will communicate with this master CTSS and validate the time. During this process if a time difference between cluster nodes is detected then it will adjust the time, same way as it is done by NTP daemon. If there is any minor time differences it will be reported in the alert.log file but if the time difference between the nodes is greater than 1000 msec then Oracle Clusterware will not startup in the non-master node and alert will be written in the alert.log file located under Clusterware home.

In such a case we need to manually set the time and start Oracle Clusterware node.

You can use CLUVFY utility as given below to view the details and the links that is between CTSS and NTP.

cluvfy comp clocksync

Verifying Clock Synchronization across the cluster nodes
Checking if Clusterware is installed on all nodes...
Check of Clusterware install passed
Checking if CTSS Resource is running on all nodes...
CTSS resource check passed
Querying CTSS for time offset on all nodes...
Query of CTSS for time offset passed
Check CTSS state started...
CTSS is in Observer state. Switching over to clock synchronization checks using NTP
Starting Clock synchronization checks using Network Time Protocol(NTP)...
NTP Configuration file check started...
NTP Configuration file check passed
Checking daemon liveness...
Liveness check passed for "ntpd"
NTP daemon slewing option check passed
TP daemon's boot time configuration check for slewing option passed
NTP common Time Server Check started...
Check of common NTP Time Server passed
Clock time offset check from NTP Time Server started...
Clock time offset check passed
Clock synchronization check using Network Time Protocol(NTP) passed
Oracle Cluster Time Synchronization Services check passed
Verification of Clock Synchronization across the cluster nodes was successful.

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