DPA: Configuring and verifying the NTP service on the Data Domain system


   Article Number:     498297                                   Article Version: 4     Article Type:    How To 




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The Network Time Protocol (NTP) is a networking protocol for clock synchronization between computer systems over packet-switched, variable-latency data networks, in other words, is a protocol to make sure date and time is correct and coordinated across all participating hosts in a network.   
    Having NTP configured on critical servers is highly recommended, because it bears significant benefits:   

  •         Log timestamps can be correlated with milisecond precision across different hosts on a network, making some sorts of problems much easier to troubleshoot     
  •         The time protocol compensates for the expected time skew on servers resulting from hardware clocks which can drift up to several seconds a month, making time to be increasing wrong for hosts not being rebooted in a long time     
  •         This is exacerbated for virtualized servers (such as DD VE, DataDomain Virtual edition , and DDMC, DataDomain Management Center) due to the nature of the virtualization process     
    This article briefly explains the CLI commands an administrator can use to setting up and modifying the current NTP configuration on any DDOS version.   







      Configuring and verifying the NTP service on the Data Domain system   



    A customer may want to configure the NTP service in the DD, or could see an error like the following posted when trying to do so:   
alert:Network Time Protocol (NTP) daemon is not running. NTP daemon has detected a time difference between this system and the configured network time server (drift) greater than the configured maximum and has shut down.Object Info:MaximumTimeDifference=10000sNTP daemon is not running.119 Thu Dec 29 03:02:36 2016 ERROR Environment EVT-NTP-00001: Network time service is failed.    

      NOTE: the error above seems to have its own KB article:     
      NTP daemon stops after running the "ntp enable" command   


      APPLIES TO:   

  •         All Data Domain systems     
  •         All software Releases      


    This article describes the steps to configure NTP service in DataDomain and troubleshooting NTP service issue   


    The error shown above is for a safeguard in NTP to prevent trying to sync date and time if the current host date and time is too far apart from the correct one: if that's the case, NTP slow "catching up" algorithm (which tries to minimise disturbance to running applications by changing time a bit at a time) may be insufficient to properly sync time, and before NTP can start, it will be necessary to manually set time within 10,000 seconds of the correct one. Below you can see some commands related to NTP:   
    1 ntp show config & ntp status    
    Check current NTP status and configuration   
    2 ntp disable    
    Disable NTP service to change NTP settings   
    3 ntp del timeserver server-name (delete the old NTP server if you want to change the NTP server)   
    4 ntp add timeserver server-name(add the new NTP server)   
    5 config set timezone Etc/GMT-12 (set the system timezone as your local time zone,here Etc/GMT-12 is an example)   
    NOTE : there are known side effects of changing a DD timezone without having planned for downtime for a DD reboot shortly after, please review:   
    EVT-GC-00002: Unable to start scheduled file system cleaning   
    Data Domain: How to modify the date/time and/or time zone on a Data Domain Restorer (DDR)   
    Timezone Change Require Reboot   
    6 After we config ntp, use command " system set date <MMDDhhmm[[CC]YY]> " to manually set the right time(time difference should be within 10,000 seconds of the correct one, or it won’t sync).   
    example : set time as Nov 20th 1PM 2017,run command : system set date 112013002017   
    7 ntp show config   
    Double confirm current NTP settings.   
    8 (optional) system reboot (to reboot the system, only required when time zone is changed)   
    9 ntp status (check NTP sync result)   
    Please note it is recommended to config the new time setting when no backup and replication is running. If you have to config the time during replication window, better to disable replication first.