This is the timestamp that triggered the most recent 'deep' checkpoint — a fuller state capture of this endpoint than the standard checkpoint records. For this blade's physical port into the chassis backplane fabric, deepCheckpointTrigTs tells an admin when the more exhaustive state capture last ran, which matters if a rollback needs the richer deep-checkpoint data rather than just the lightweight standard checkpoint. This value only advances on the less frequent deep-checkpoint cycle, so it may lag well behind checkpointTrigTs for the same endpoint.