diff --git a/weed/server/master_server_handlers_admin.go b/weed/server/master_server_handlers_admin.go
index 5b0fe26de..7b1ec1f87 100644
--- a/weed/server/master_server_handlers_admin.go
+++ b/weed/server/master_server_handlers_admin.go
@@ -77,7 +77,7 @@ func (ms *MasterServer) volumeGrowHandler(w http.ResponseWriter, r *http.Request
 
 	if count, err = strconv.Atoi(r.FormValue("count")); err == nil {
 		if ms.Topo.AvailableSpaceFor(option) < int64(count*option.ReplicaPlacement.GetCopyCount()) {
-			err = fmt.Errorf("only %d volumes left, not enough for %d", ms.Topo.FreeSpace(), count*option.ReplicaPlacement.GetCopyCount())
+			err = fmt.Errorf("only %d volumes left, not enough for %d", ms.Topo.AvailableSpaceFor(option), count*option.ReplicaPlacement.GetCopyCount())
 		} else {
 			count, err = ms.vg.GrowByCountAndType(ms.grpcDialOption, count, option, ms.Topo)
 		}
diff --git a/weed/topology/node.go b/weed/topology/node.go
index 8f525021f..b5c2680dd 100644
--- a/weed/topology/node.go
+++ b/weed/topology/node.go
@@ -18,7 +18,8 @@ type Node interface {
 	Id() NodeId
 	String() string
 	FreeSpace() int64
-	ReserveOneVolume(r int64) (*DataNode, error)
+	AvailableSpaceFor(option *VolumeGrowOption) int64
+	ReserveOneVolume(r int64, option *VolumeGrowOption) (*DataNode, error)
 	UpAdjustMaxVolumeCountDelta(maxVolumeCountDelta int64)
 	UpAdjustMaxSsdVolumeCountDelta(maxSsdVolumeCountDelta int64)
 	UpAdjustVolumeCountDelta(volumeCountDelta int64)
@@ -69,7 +70,7 @@ type NodeImpl struct {
 }
 
 // the first node must satisfy filterFirstNodeFn(), the rest nodes must have one free slot
-func (n *NodeImpl) PickNodesByWeight(numberOfNodes int, filterFirstNodeFn func(dn Node) error) (firstNode Node, restNodes []Node, err error) {
+func (n *NodeImpl) PickNodesByWeight(numberOfNodes int, option *VolumeGrowOption, filterFirstNodeFn func(dn Node) error) (firstNode Node, restNodes []Node, err error) {
 	var totalWeights int64
 	var errs []string
 	n.RLock()
@@ -77,12 +78,12 @@ func (n *NodeImpl) PickNodesByWeight(numberOfNodes int, filterFirstNodeFn func(d
 	candidatesWeights := make([]int64, 0, len(n.children))
 	//pick nodes which has enough free volumes as candidates, and use free volumes number as node weight.
 	for _, node := range n.children {
-		if node.FreeSpace() <= 0 {
+		if node.AvailableSpaceFor(option) <= 0 {
 			continue
 		}
-		totalWeights += node.FreeSpace()
+		totalWeights += node.AvailableSpaceFor(option)
 		candidates = append(candidates, node)
-		candidatesWeights = append(candidatesWeights, node.FreeSpace())
+		candidatesWeights = append(candidatesWeights, node.AvailableSpaceFor(option))
 	}
 	n.RUnlock()
 	if len(candidates) < numberOfNodes {
@@ -183,11 +184,11 @@ func (n *NodeImpl) Parent() Node {
 func (n *NodeImpl) GetValue() interface{} {
 	return n.value
 }
-func (n *NodeImpl) ReserveOneVolume(r int64) (assignedNode *DataNode, err error) {
+func (n *NodeImpl) ReserveOneVolume(r int64, option *VolumeGrowOption) (assignedNode *DataNode, err error) {
 	n.RLock()
 	defer n.RUnlock()
 	for _, node := range n.children {
-		freeSpace := node.FreeSpace()
+		freeSpace := node.AvailableSpaceFor(option)
 		// fmt.Println("r =", r, ", node =", node, ", freeSpace =", freeSpace)
 		if freeSpace <= 0 {
 			continue
@@ -195,11 +196,11 @@ func (n *NodeImpl) ReserveOneVolume(r int64) (assignedNode *DataNode, err error)
 		if r >= freeSpace {
 			r -= freeSpace
 		} else {
-			if node.IsDataNode() && node.FreeSpace() > 0 {
+			if node.IsDataNode() && node.AvailableSpaceFor(option) > 0 {
 				// fmt.Println("vid =", vid, " assigned to node =", node, ", freeSpace =", node.FreeSpace())
 				return node.(*DataNode), nil
 			}
-			assignedNode, err = node.ReserveOneVolume(r)
+			assignedNode, err = node.ReserveOneVolume(r, option)
 			if err == nil {
 				return
 			}
diff --git a/weed/topology/volume_growth.go b/weed/topology/volume_growth.go
index 260013c38..1ceca06a5 100644
--- a/weed/topology/volume_growth.go
+++ b/weed/topology/volume_growth.go
@@ -114,21 +114,21 @@ func (vg *VolumeGrowth) findAndGrow(grpcDialOption grpc.DialOption, topo *Topolo
 func (vg *VolumeGrowth) findEmptySlotsForOneVolume(topo *Topology, option *VolumeGrowOption) (servers []*DataNode, err error) {
 	//find main datacenter and other data centers
 	rp := option.ReplicaPlacement
-	mainDataCenter, otherDataCenters, dc_err := topo.PickNodesByWeight(rp.DiffDataCenterCount+1, func(node Node) error {
+	mainDataCenter, otherDataCenters, dc_err := topo.PickNodesByWeight(rp.DiffDataCenterCount+1, option, func(node Node) error {
 		if option.DataCenter != "" && node.IsDataCenter() && node.Id() != NodeId(option.DataCenter) {
 			return fmt.Errorf("Not matching preferred data center:%s", option.DataCenter)
 		}
 		if len(node.Children()) < rp.DiffRackCount+1 {
 			return fmt.Errorf("Only has %d racks, not enough for %d.", len(node.Children()), rp.DiffRackCount+1)
 		}
-		if node.FreeSpace() < int64(rp.DiffRackCount+rp.SameRackCount+1) {
-			return fmt.Errorf("Free:%d < Expected:%d", node.FreeSpace(), rp.DiffRackCount+rp.SameRackCount+1)
+		if node.AvailableSpaceFor(option) < int64(rp.DiffRackCount+rp.SameRackCount+1) {
+			return fmt.Errorf("Free:%d < Expected:%d", node.AvailableSpaceFor(option), rp.DiffRackCount+rp.SameRackCount+1)
 		}
 		possibleRacksCount := 0
 		for _, rack := range node.Children() {
 			possibleDataNodesCount := 0
 			for _, n := range rack.Children() {
-				if n.FreeSpace() >= 1 {
+				if n.AvailableSpaceFor(option) >= 1 {
 					possibleDataNodesCount++
 				}
 			}
@@ -146,12 +146,12 @@ func (vg *VolumeGrowth) findEmptySlotsForOneVolume(topo *Topology, option *Volum
 	}
 
 	//find main rack and other racks
-	mainRack, otherRacks, rackErr := mainDataCenter.(*DataCenter).PickNodesByWeight(rp.DiffRackCount+1, func(node Node) error {
+	mainRack, otherRacks, rackErr := mainDataCenter.(*DataCenter).PickNodesByWeight(rp.DiffRackCount+1, option, func(node Node) error {
 		if option.Rack != "" && node.IsRack() && node.Id() != NodeId(option.Rack) {
 			return fmt.Errorf("Not matching preferred rack:%s", option.Rack)
 		}
-		if node.FreeSpace() < int64(rp.SameRackCount+1) {
-			return fmt.Errorf("Free:%d < Expected:%d", node.FreeSpace(), rp.SameRackCount+1)
+		if node.AvailableSpaceFor(option) < int64(rp.SameRackCount+1) {
+			return fmt.Errorf("Free:%d < Expected:%d", node.AvailableSpaceFor(option), rp.SameRackCount+1)
 		}
 		if len(node.Children()) < rp.SameRackCount+1 {
 			// a bit faster way to test free racks
@@ -159,7 +159,7 @@ func (vg *VolumeGrowth) findEmptySlotsForOneVolume(topo *Topology, option *Volum
 		}
 		possibleDataNodesCount := 0
 		for _, n := range node.Children() {
-			if n.FreeSpace() >= 1 {
+			if n.AvailableSpaceFor(option) >= 1 {
 				possibleDataNodesCount++
 			}
 		}
@@ -173,12 +173,12 @@ func (vg *VolumeGrowth) findEmptySlotsForOneVolume(topo *Topology, option *Volum
 	}
 
 	//find main rack and other racks
-	mainServer, otherServers, serverErr := mainRack.(*Rack).PickNodesByWeight(rp.SameRackCount+1, func(node Node) error {
+	mainServer, otherServers, serverErr := mainRack.(*Rack).PickNodesByWeight(rp.SameRackCount+1, option, func(node Node) error {
 		if option.DataNode != "" && node.IsDataNode() && node.Id() != NodeId(option.DataNode) {
 			return fmt.Errorf("Not matching preferred data node:%s", option.DataNode)
 		}
-		if node.FreeSpace() < 1 {
-			return fmt.Errorf("Free:%d < Expected:%d", node.FreeSpace(), 1)
+		if node.AvailableSpaceFor(option) < 1 {
+			return fmt.Errorf("Free:%d < Expected:%d", node.AvailableSpaceFor(option), 1)
 		}
 		return nil
 	})
@@ -191,16 +191,16 @@ func (vg *VolumeGrowth) findEmptySlotsForOneVolume(topo *Topology, option *Volum
 		servers = append(servers, server.(*DataNode))
 	}
 	for _, rack := range otherRacks {
-		r := rand.Int63n(rack.FreeSpace())
-		if server, e := rack.ReserveOneVolume(r); e == nil {
+		r := rand.Int63n(rack.AvailableSpaceFor(option))
+		if server, e := rack.ReserveOneVolume(r, option); e == nil {
 			servers = append(servers, server)
 		} else {
 			return servers, e
 		}
 	}
 	for _, datacenter := range otherDataCenters {
-		r := rand.Int63n(datacenter.FreeSpace())
-		if server, e := datacenter.ReserveOneVolume(r); e == nil {
+		r := rand.Int63n(datacenter.AvailableSpaceFor(option))
+		if server, e := datacenter.ReserveOneVolume(r, option); e == nil {
 			servers = append(servers, server)
 		} else {
 			return servers, e