Oracle Time Synchronization

Time synchronization between nodes is important for Oracle and is often done by setting up an NTP server before the 11g release. In Oracle 11g, a new CTSS (Cluster time Synchronization Services, cluster synchronization Service) service was added to complete the time synchronization between cluster nodes. During the installation of the grid infrastructure, CTSS is automatically installed if no nodes are found to have an NTP service.
1. NTP Time Synchronization Service configuration
NTP is a traditional time synchronization service, often in an enterprise has a dedicated time synchronization server, this situation can still use NTP to synchronize the time between the nodes.
2. CTSS Time Synchronization Service configuration
In the 11GR2 version, Oracle has launched its own time synchronization service, which is only valid on all nodes of a RAC and is not synchronized with the time of other systems. If you want to use CTSS synchronization time, in addition to stopping and preventing the automatic restart of the NTP service, the/etc/ntp.conf configuration file is not allowed to exist, perform the following steps to clear the NTP service.
(1) Stop NTP service
/sbin/service ntpd Stop
(2) Disable NTP server self-boot
Chkconfig ntpd off
(3) Delete or rename an NTP configuration file
Rm/etc/ntp.conf
Or:
Mv/etc/ntp.conf/etc/ntp.conf.bak
This clears the NTP completely and automatically creates the CTSS when the grid infrastructure is installed.
3. CTSS check failed
The last step in installing grid infrastructure is likely to have the following error:
INFO:CTSS is in Active state. Proceeding with check of clock time offsets on all nodes ...
Info:prvf-9661:time offset isn't within the specified limits on the following nodes:
INFO: "[Rhel2]"
Info:prvf-9652:cluster Time synchronization Services check failed
Info:post-check for Cluster Services setup is unsuccessful on all the nodes.
INFO:
WARNING:
info:completed Plugin named:oracle Cluster Verification Utility
For the above error, the following methods are handled:
1) Determine if the time zone for all the RAC nodes is consistent.
2) The CTSS check failed due to the time interval over the assembly. Therefore, to manually adjust the host's time before performing this step, ensure that the time between hosts is consistent.
2.5.9 Installing the Cvuqdisk package
Step 1 upload the installation package.
Use the Sftp method to upload the grid Infrastructure, database installation media to the/u01/soft directory. Two products contain the following 3 Zip packages:
Q Linux.x64_11gR2_grid.zip
Q Linux.x64_11gR2_database_1of2.zip
Q Linux.x64_11gR2_database_2of2.zip
Linux.x64_11gR2_grid.zip is the installation package for grid infrastructure, linux.x64_11gr2_ Database_1of2.zip and Linux.x64_11gr2_database_ 2of2.zip is the database's two installation package, before installing database to extract the two packages to the same directory to properly install database.
Step 2 Install Cvuqdisk.
Unzip the Linux.x64_11gR2_grid.zip file, locate cvuqdisk-1.0.7-1.rpm under the extracted grid/rpm directory, and execute the following Cvuqdisk Package installation command:
#CVUQDISK_GRP =oinstall; Export CVUQDISK_GRP
#rpm-IVH cvuqdisk-1.0.7-1.rpm
Transfer this file to other cluster nodes via SFTP and install the package as described above.
2.5.10 CVU Verifying the installation environment
It is necessary to use the CVU tool before installation to verify that the current environment has the conditions for setting up an Oracle RAC. By using this tool, you can also find configuration issues before you perform a specific installation. Execute the following command to check the installation environment:
./runcluvfy.sh Stage-pre Crsinst-n Rhel1,rhel2-fixup-verbose
......
Check:membership of user "grid" in Group "DBA"
Node Name User Exists Group Exists user in Group Comment
----------     -------       ------------  ------------   ---------
Rhel2 Yes yes No failed
Rhel1 Yes yes No failed
Result:membership Check for the user "grid" in Group "DBA" failed
......
The verification process should not have failed, the above user's verification failure is because the CVU tool does not recognize the grid user-specified Asmadmin, ASMDBA, Asmoper group, it still use the DBA operating system group as a criterion, so reported this error, You can ignore this error when you are sure that the grid user group is set up correctly.

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Oracle Time Synchronization