Checking Time Consistency

Database transaction consistency is guaranteed by a logical clock and is not affected by OS time. However, OS time inconsistency will lead to problems, such as abnormal backend O&M and monitoring functions. Therefore, you are advised to monthly check time consistency among nodes.

Procedure

1. Log in as the OS user omm to the primary node of the database.

2. Create a configuration file for each openGauss node. The mpphosts file directory can be specified by users. The /tmp directory is recommended.

   vim /tmp/mpphosts
   

   Add the host name of each node.

   plat1
   plat2
   plat3
   

3. Save the configuration file.

   :wq!
   

4. Run the following command and write the time on each node into the /tmp/sys_ctl-os1.log file:

   for ihost in `cat /tmp/mpphosts`; do ssh -n -q $ihost "hostname;date"; done > /tmp/sys_ctl-os1.log
   

5. Check time consistency between the nodes based on the command output. The time difference should not exceed 30s.

   cat /tmp/sys_ctl-os1.log
   plat1
   Thu Feb  9 16:46:38 CST 2017
   plat2
   Thu Feb  9 16:46:49 CST 2017
   plat3
   Thu Feb  9 16:46:14 CST 2017