You should enable the DD Retention lock option on the MTree in Data Domain Console prior to enabling WORM storage lock in CommCell Console.
Configure the WORM storage lock on the Data Domain Boost Storage Library. For more information, see Enabling WORM Storage and Retention for Disk Storage. The WORM lock days configured in Commvault storage pool should be set between the Retention period min and Retention period max values set in Data Domain Console under the DD Retention Lock setting. WORM Lock days is shown on the Storage Policy Copy Properties dialog box. The DD Retention Lock can be set to either Governance mode or Compliance mode.
Data Domain Retention Lock setting to one day less than the retention set in Commvault and maximum retention to 2x+1 than the retention set in Commvault on the storage pool. For example, if the minimum retention in Commvault is 14 days, then set the minimum retention to 13 days and maximum retention to 29 days in Data Domain Console.