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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 any host in the MogDB Kernel cluster.
  2. Create a configuration file for recording each cluster node. (You can specify the mpphosts file directory randomly. It is recommended that the file be stored in the /tmp directory.)

    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