Add debug message

Author: nvazquez

server/src/main/java/com/cloud/storage/StorageManagerImpl.java

@@ -1395,6 +1395,9 @@ public void cleanupSecondaryStorage(boolean recurring) {
                         _snapshotDao.remove(destroyedSnapshotStoreVO.getSnapshotId());
                         SnapshotDataStoreVO snapshotOnPrimary = _snapshotStoreDao.findDestroyedReferenceBySnapshot(destroyedSnapshotStoreVO.getSnapshotId(), DataStoreRole.Primary);
                         if (snapshotOnPrimary != null) {
+                            if (s_logger.isDebugEnabled()) {
+                                s_logger.debug("Deleting snapshot on primary store reference DB entry: " + snapshotOnPrimary);
+                            }
                             _snapshotStoreDao.remove(snapshotOnPrimary.getId());
                         }
                         _snapshotStoreDao.remove(destroyedSnapshotStoreVO.getId());