diff --git a/go/storage/cdb_map.go b/go/storage/cdb_map.go
index 0d790cc0f..8be302111 100644
--- a/go/storage/cdb_map.go
+++ b/go/storage/cdb_map.go
@@ -64,6 +64,10 @@ func (m *cdbMap) Close() {
 	}
 }
 
+func (m *cdbMap) Destroy() error {
+	return errors.New("Can not delete readonly volumes")
+}
+
 func (m cdbMap) ContentSize() uint64 {
 	return m.FileByteCounter
 }
diff --git a/go/storage/needle_map.go b/go/storage/needle_map.go
index 29b71ae52..ef7d3d6fd 100644
--- a/go/storage/needle_map.go
+++ b/go/storage/needle_map.go
@@ -14,6 +14,7 @@ type NeedleMapper interface {
 	Get(key uint64) (element *NeedleValue, ok bool)
 	Delete(key uint64) error
 	Close()
+	Destroy() error
 	ContentSize() uint64
 	DeletedSize() uint64
 	FileCount() int
@@ -155,6 +156,10 @@ func (nm *NeedleMap) Delete(key uint64) error {
 func (nm *NeedleMap) Close() {
 	_ = nm.indexFile.Close()
 }
+func (nm *NeedleMap) Destroy() error {
+	nm.Close()
+	return os.Remove(nm.indexFile.Name())
+}
 func (nm NeedleMap) ContentSize() uint64 {
 	return nm.FileByteCounter
 }
diff --git a/go/storage/store.go b/go/storage/store.go
index 2df0e6cb7..e1babd1e5 100644
--- a/go/storage/store.go
+++ b/go/storage/store.go
@@ -111,6 +111,20 @@ func (s *Store) AddVolume(volumeListString string, collection string, replicaPla
 	}
 	return e
 }
+func (s *Store) DeleteCollection(collection string) (e error) {
+	for _, location := range s.locations {
+		for k, v := range location.volumes {
+			if v.Collection == collection {
+				e = v.Destroy()
+				if e != nil {
+					return
+				}
+				delete(location.volumes, k)
+			}
+		}
+	}
+	return
+}
 func (s *Store) findVolume(vid VolumeId) *Volume {
 	for _, location := range s.locations {
 		if v, found := location.volumes[vid]; found {
diff --git a/go/storage/volume.go b/go/storage/volume.go
index 69817a6d4..0301d7968 100644
--- a/go/storage/volume.go
+++ b/go/storage/volume.go
@@ -197,6 +197,21 @@ func (v *Volume) isFileUnchanged(n *Needle) bool {
 	}
 	return false
 }
+
+func (v *Volume) Destroy() (err error) {
+	if v.readOnly {
+		err = fmt.Errorf("%s is read-only", v.dataFile)
+		return
+	}
+	v.Close()
+	err = os.Remove(v.dataFile.Name())
+	if err != nil {
+		return
+	}
+	err = v.nm.Destroy()
+	return
+}
+
 func (v *Volume) write(n *Needle) (size uint32, err error) {
 	if v.readOnly {
 		err = fmt.Errorf("%s is read-only", v.dataFile)
diff --git a/go/topology/collection.go b/go/topology/collection.go
index 8042369a9..b21122d22 100644
--- a/go/topology/collection.go
+++ b/go/topology/collection.go
@@ -36,3 +36,14 @@ func (c *Collection) Lookup(vid storage.VolumeId) []*DataNode {
 	}
 	return nil
 }
+
+func (c *Collection) ListVolumeServers() (nodes []*DataNode) {
+	for _, vl := range c.replicaType2VolumeLayout {
+		if vl != nil {
+			if list := vl.ListVolumeServers(); list != nil {
+				nodes = append(nodes, list...)
+			}
+		}
+	}
+	return
+}
diff --git a/go/topology/data_node.go b/go/topology/data_node.go
index 3a6edb447..a83647939 100644
--- a/go/topology/data_node.go
+++ b/go/topology/data_node.go
@@ -1,8 +1,8 @@
 package topology
 
 import (
+	"code.google.com/p/weed-fs/go/glog"
 	"code.google.com/p/weed-fs/go/storage"
-	_ "fmt"
 	"strconv"
 )
 
@@ -28,12 +28,32 @@ func (dn *DataNode) AddOrUpdateVolume(v storage.VolumeInfo) {
 	if _, ok := dn.volumes[v.Id]; !ok {
 		dn.volumes[v.Id] = v
 		dn.UpAdjustVolumeCountDelta(1)
-		dn.UpAdjustActiveVolumeCountDelta(1)
+		if !v.ReadOnly {
+			dn.UpAdjustActiveVolumeCountDelta(1)
+		}
 		dn.UpAdjustMaxVolumeId(v.Id)
 	} else {
 		dn.volumes[v.Id] = v
 	}
 }
+func (dn *DataNode) UpdateVolumes(actualVolumes []storage.VolumeInfo) {
+	actualVolumeMap := make(map[storage.VolumeId]storage.VolumeInfo)
+	for _, v := range actualVolumes {
+		actualVolumeMap[v.Id] = v
+	}
+	for vid, _ := range dn.volumes {
+		glog.V(2).Infoln("Checking volume id:", vid)
+		if _, ok := actualVolumeMap[vid]; !ok {
+			glog.V(0).Infoln("Deleting volume id:", vid)
+			delete(dn.volumes, vid)
+			dn.UpAdjustVolumeCountDelta(-1)
+			dn.UpAdjustActiveVolumeCountDelta(-1)
+		}
+	} //TODO: adjust max volume id, if need to reclaim volume ids
+	for _, v := range actualVolumes {
+		dn.AddOrUpdateVolume(v)
+	}
+}
 func (dn *DataNode) GetDataCenter() *DataCenter {
 	return dn.Parent().Parent().(*NodeImpl).value.(*DataCenter)
 }
diff --git a/go/topology/topology.go b/go/topology/topology.go
index 1426f7a12..d72879035 100644
--- a/go/topology/topology.go
+++ b/go/topology/topology.go
@@ -99,6 +99,15 @@ func (t *Topology) GetVolumeLayout(collectionName string, rp *storage.ReplicaPla
 	return t.collectionMap[collectionName].GetOrCreateVolumeLayout(rp)
 }
 
+func (t *Topology) GetCollection(collectionName string) (collection *Collection, ok bool) {
+	collection, ok = t.collectionMap[collectionName]
+	return
+}
+
+func (t *Topology) DeleteCollection(collectionName string) {
+	delete(t.collectionMap, collectionName)
+}
+
 func (t *Topology) RegisterVolumeLayout(v *storage.VolumeInfo, dn *DataNode) {
 	t.GetVolumeLayout(v.Collection, v.ReplicaPlacement).RegisterVolume(v, dn)
 }
@@ -112,8 +121,8 @@ func (t *Topology) RegisterVolumes(init bool, volumeInfos []storage.VolumeInfo,
 		t.UnRegisterDataNode(dn)
 	}
 	dn = rack.GetOrCreateDataNode(ip, port, publicUrl, maxVolumeCount)
+	dn.UpdateVolumes(volumeInfos)
 	for _, v := range volumeInfos {
-		dn.AddOrUpdateVolume(v)
 		t.RegisterVolumeLayout(&v, dn)
 	}
 }
diff --git a/go/topology/topology_event_handling.go b/go/topology/topology_event_handling.go
index 5740c9a03..710e7b2ae 100644
--- a/go/topology/topology_event_handling.go
+++ b/go/topology/topology_event_handling.go
@@ -46,7 +46,9 @@ func (t *Topology) SetVolumeCapacityFull(volumeInfo storage.VolumeInfo) bool {
 		return false
 	}
 	for _, dn := range vl.vid2location[volumeInfo.Id].list {
-		dn.UpAdjustActiveVolumeCountDelta(-1)
+		if !volumeInfo.ReadOnly {
+			dn.UpAdjustActiveVolumeCountDelta(-1)
+		}
 	}
 	return true
 }
diff --git a/go/topology/volume_layout.go b/go/topology/volume_layout.go
index 40628b4a0..1a35faa5c 100644
--- a/go/topology/volume_layout.go
+++ b/go/topology/volume_layout.go
@@ -8,6 +8,7 @@ import (
 	"sync"
 )
 
+// mapping from volume to its locations, inverted from server to volume
 type VolumeLayout struct {
 	rp              *storage.ReplicaPlacement
 	vid2location    map[storage.VolumeId]*VolumeLocationList
@@ -56,6 +57,13 @@ func (vl *VolumeLayout) Lookup(vid storage.VolumeId) []*DataNode {
 	return nil
 }
 
+func (vl *VolumeLayout) ListVolumeServers() (nodes []*DataNode) {
+	for _, location := range vl.vid2location {
+		nodes = append(nodes, location.list...)
+	}
+	return
+}
+
 func (vl *VolumeLayout) PickForWrite(count int, dataCenter string) (*storage.VolumeId, int, *VolumeLocationList, error) {
 	len_writers := len(vl.writables)
 	if len_writers <= 0 {
@@ -134,10 +142,12 @@ func (vl *VolumeLayout) SetVolumeUnavailable(dn *DataNode, vid storage.VolumeId)
 	vl.accessLock.Lock()
 	defer vl.accessLock.Unlock()
 
-	if vl.vid2location[vid].Remove(dn) {
-		if vl.vid2location[vid].Length() < vl.rp.GetCopyCount() {
-			glog.V(0).Infoln("Volume", vid, "has", vl.vid2location[vid].Length(), "replica, less than required", vl.rp.GetCopyCount())
-			return vl.removeFromWritable(vid)
+	if location, ok := vl.vid2location[vid]; ok {
+		if location.Remove(dn) {
+			if location.Length() < vl.rp.GetCopyCount() {
+				glog.V(0).Infoln("Volume", vid, "has", location.Length(), "replica, less than required", vl.rp.GetCopyCount())
+				return vl.removeFromWritable(vid)
+			}
 		}
 	}
 	return false
diff --git a/go/weed/weed_server/master_server.go b/go/weed/weed_server/master_server.go
index c1870e79e..d17e57531 100644
--- a/go/weed/weed_server/master_server.go
+++ b/go/weed/weed_server/master_server.go
@@ -60,6 +60,7 @@ func NewMasterServer(r *mux.Router, version string, port int, metaFolder string,
 	r.HandleFunc("/dir/lookup", ms.proxyToLeader(secure(ms.whiteList, ms.dirLookupHandler)))
 	r.HandleFunc("/dir/join", ms.proxyToLeader(secure(ms.whiteList, ms.dirJoinHandler)))
 	r.HandleFunc("/dir/status", ms.proxyToLeader(secure(ms.whiteList, ms.dirStatusHandler)))
+	r.HandleFunc("/col/delete", ms.proxyToLeader(secure(ms.whiteList, ms.collectionDeleteHandler)))
 	r.HandleFunc("/vol/grow", ms.proxyToLeader(secure(ms.whiteList, ms.volumeGrowHandler)))
 	r.HandleFunc("/vol/status", ms.proxyToLeader(secure(ms.whiteList, ms.volumeStatusHandler)))
 	r.HandleFunc("/vol/vacuum", ms.proxyToLeader(secure(ms.whiteList, ms.volumeVacuumHandler)))
diff --git a/go/weed/weed_server/master_server_handlers.go b/go/weed/weed_server/master_server_handlers.go
index 0c710429c..64786dc10 100644
--- a/go/weed/weed_server/master_server_handlers.go
+++ b/go/weed/weed_server/master_server_handlers.go
@@ -2,6 +2,7 @@ package weed_server
 
 import (
 	"code.google.com/p/weed-fs/go/storage"
+	"code.google.com/p/weed-fs/go/util"
 	"encoding/json"
 	"errors"
 	"net/http"
@@ -78,6 +79,22 @@ func (ms *MasterServer) dirAssignHandler(w http.ResponseWriter, r *http.Request)
 	}
 }
 
+func (ms *MasterServer) collectionDeleteHandler(w http.ResponseWriter, r *http.Request) {
+	collection, ok := ms.topo.GetCollection(r.FormValue("collection"))
+	if !ok {
+		writeJsonQuiet(w, r, map[string]interface{}{"error": "collection " + r.FormValue("collection") + "does not exist!"})
+		return
+	}
+	for _, server := range collection.ListVolumeServers() {
+		_, err := util.Get("http://" + server.Ip + ":" + strconv.Itoa(server.Port) + "/admin/delete_collection?collection=" + r.FormValue("collection"))
+		if err != nil {
+			writeJsonQuiet(w, r, map[string]string{"error": err.Error()})
+			return
+		}
+	}
+	ms.topo.DeleteCollection(r.FormValue("collection"))
+}
+
 func (ms *MasterServer) dirJoinHandler(w http.ResponseWriter, r *http.Request) {
 	init := r.FormValue("init") == "true"
 	ip := r.FormValue("ip")
diff --git a/go/weed/weed_server/volume_server.go b/go/weed/weed_server/volume_server.go
index a2939f848..b4fc4f4ea 100644
--- a/go/weed/weed_server/volume_server.go
+++ b/go/weed/weed_server/volume_server.go
@@ -39,6 +39,7 @@ func NewVolumeServer(r *http.ServeMux, version string, ip string, port int, publ
 	r.HandleFunc("/admin/vacuum_volume_compact", secure(vs.whiteList, vs.vacuumVolumeCompactHandler))
 	r.HandleFunc("/admin/vacuum_volume_commit", secure(vs.whiteList, vs.vacuumVolumeCommitHandler))
 	r.HandleFunc("/admin/freeze_volume", secure(vs.whiteList, vs.freezeVolumeHandler))
+	r.HandleFunc("/admin/delete_collection", secure(vs.whiteList, vs.deleteCollectionHandler))
 	r.HandleFunc("/", vs.storeHandler)
 
 	go func() {
diff --git a/go/weed/weed_server/volume_server_handlers.go b/go/weed/weed_server/volume_server_handlers.go
index 2f4673763..a7ea8ad87 100644
--- a/go/weed/weed_server/volume_server_handlers.go
+++ b/go/weed/weed_server/volume_server_handlers.go
@@ -29,6 +29,19 @@ func (vs *VolumeServer) assignVolumeHandler(w http.ResponseWriter, r *http.Reque
 	}
 	glog.V(2).Infoln("assign volume =", r.FormValue("volume"), ", collection =", r.FormValue("collection"), ", replication =", r.FormValue("replication"), ", error =", err)
 }
+func (vs *VolumeServer) deleteCollectionHandler(w http.ResponseWriter, r *http.Request) {
+	if "benchmark" != r.FormValue("collection") {
+		glog.V(0).Infoln("deleting collection =", r.FormValue("collection"), "!!!")
+		return
+	}
+	err := vs.store.DeleteCollection(r.FormValue("collection"))
+	if err == nil {
+		writeJsonQuiet(w, r, map[string]string{"error": ""})
+	} else {
+		writeJsonQuiet(w, r, map[string]string{"error": err.Error()})
+	}
+	glog.V(2).Infoln("deleting collection =", r.FormValue("collection"), ", error =", err)
+}
 func (vs *VolumeServer) vacuumVolumeCheckHandler(w http.ResponseWriter, r *http.Request) {
 	err, ret := vs.store.CheckCompactVolume(r.FormValue("volume"), r.FormValue("garbageThreshold"))
 	if err == nil {