diff --git a/usage/src/com/cloud/usage/parser/VolumeUsageParser.java b/usage/src/com/cloud/usage/parser/VolumeUsageParser.java
index 2ac1e0a8f84..b6a12de9d16 100644
--- a/usage/src/com/cloud/usage/parser/VolumeUsageParser.java
+++ b/usage/src/com/cloud/usage/parser/VolumeUsageParser.java
@@ -85,7 +85,7 @@ public class VolumeUsageParser {
             long zoneId = usageVol.getZoneId();
             Long templateId = usageVol.getTemplateId();
             long size = usageVol.getSize();
-            String key = ""+volId;
+            String key = volId + "-" + doId + "-" + size;
 
             diskOfferingMap.put(key, new VolInfo(volId, zoneId, doId, templateId, size));