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Prior to initiating an upgrade of the Dell UnityOS, it is recommended to pause all ongoing replication sessions, but it is not required. The Pre-Upgrade Health Check (PUHC) checks for any active replication sessions and generates a warning if any are found. Once the upgrade completes, you can resume each replication session. The pause and resume operations should be initiated from the source system for each replication session. If you are running Dell UnityOS version 4.2 or later, pausing and resuming the NAS server replication session also pauses and resumes all its associated file system replication sessions automatically.
For more information on upgrading system to Dell UnityOS 5.2, see the Upgrade a system that has an advanced replication topology in the Dell Unity Family Configuring Replication guide on Dell Support.