Major:

change replication_type to ReplicaPlacement, hopefully cleaner code
works for 9 possible ReplicaPlacement
xyz
x : number of copies on other data centers
y : number of copies on other racks
z : number of copies on current rack
x y z each can be 0,1,2

Minor:
weed server "-mdir" default to "-dir" if empty

go/storage/cdb_map.go

@@ -76,8 +76,8 @@ func (m cdbMap) FileCount() int {
 func (m *cdbMap) DeletedCount() int {
 	return m.DeletionCounter
 }
-func (m *cdbMap) NextFileKey(count int) (uint64) {
-  return 0
+func (m *cdbMap) NextFileKey(count int) uint64 {
+	return 0
 }
 
 func getMetric(c *cdb.Cdb, m *mapMetric) error {