diff --git a/swift/common/ring/builder.py b/swift/common/ring/builder.py
index 43b9288..6b761e9 100644
--- a/swift/common/ring/builder.py
+++ b/swift/common/ring/builder.py
@@ -368,8 +368,17 @@ class RingBuilder(object):
         # Only changed device ids are taken into account; devices might be
         # "touched" during the rebalance, but actually not really moved
         changed_parts = 0
-        for rep_id, _rep in enumerate(self._replica2part2dev):
-            for part_id, new_device in enumerate(_rep):
+        # While iterating over placement count parts who have multiple more
+        # replicas than the maximum number of replicas wanted for that tier
+        max_replicas = self._build_max_replicas_by_tier()
+        at_risk_parts = 0
+        for part_id, dev_ids in enumerate(
+                itertools.izip(*self._replica2part2dev)):
+            replicas_at_tier = defaultdict(int)
+            for rep_id, dev in enumerate(iter(
+                    self.devs[dev_id] for dev_id in dev_ids)):
+                for tier in tiers_for_dev(dev):
+                    replicas_at_tier[tier] += 1
                 # IndexErrors will be raised if the replicas are increased or
                 # decreased, and that actually means the partition has changed
                 try:
@@ -378,8 +387,22 @@ class RingBuilder(object):
                     changed_parts += 1
                     continue

-                if old_device != new_device:
+                if old_device != dev:
                     changed_parts += 1
+            for tier, replicas in replicas_at_tier.items():
+                if replicas > max_replicas[tier]:
+                    print 'part %s is at risk in %s because %s > %s' % (
+                        part_id, tier, replicas, max_replicas[tier])
+                    at_risk_parts += 1
+                    break
+        dispersion = 1.0 * (self.parts - at_risk_parts) / self.parts
+        print at_risk_parts, dispersion
+
+        # we'll want to cache dispersion on the builder, clear it on
+        # rebalance, and add it to the return signature (possibly with a
+        # backwards compatibility shim) so that the command line utility can
+        # display a warning and recommend the operator evaluate the situation
+        # with the dispersion command.
         return changed_parts, balance

     def validate(self, stats=False):