 
 
         destroy: =>
-            @datacenter.off 'all', @render
+            if @datacenter?
+                @datacenter.off 'all', @render
 
             @model.off 'change:primary_uuid', @render
             progress_list.off 'all', @render_progress

            @render()

        render_progress: =>
            progress_data = DataUtils.get_backfill_progress_agg @model.get('id'), @datacenter.get('id')

            if progress_data? and _.isNaN(progress_data.percentage) is false

                @.$('.progress_bar_full_container').slideUp 'fast'

        render: =>
            if not @datacenter?
                return ''
            replicas_count = DataUtils.get_replica_affinities(@model.get('id'), @datacenter.get('id'))
            if @model.get('primary_uuid') is @datacenter.get('id')
                replicas_count++
