diff --git a/weed/notification/gocdk_pub_sub/gocdk_pub_sub.go b/weed/notification/gocdk_pub_sub/gocdk_pub_sub.go
index 94a413ac0..ebf44ea6f 100644
--- a/weed/notification/gocdk_pub_sub/gocdk_pub_sub.go
+++ b/weed/notification/gocdk_pub_sub/gocdk_pub_sub.go
@@ -24,7 +24,7 @@ import (
 	"github.com/golang/protobuf/proto"
 	"gocloud.dev/pubsub"
 	_ "gocloud.dev/pubsub/awssnssqs"
-	_ "gocloud.dev/pubsub/azuresb"
+	// _ "gocloud.dev/pubsub/azuresb"
 	_ "gocloud.dev/pubsub/gcppubsub"
 	_ "gocloud.dev/pubsub/natspubsub"
 	_ "gocloud.dev/pubsub/rabbitpubsub"
diff --git a/weed/replication/sub/notification_gocdk_pub_sub.go b/weed/replication/sub/notification_gocdk_pub_sub.go
index 9c76e6918..eddba9ff8 100644
--- a/weed/replication/sub/notification_gocdk_pub_sub.go
+++ b/weed/replication/sub/notification_gocdk_pub_sub.go
@@ -9,7 +9,7 @@ import (
 	"github.com/golang/protobuf/proto"
 	"gocloud.dev/pubsub"
 	_ "gocloud.dev/pubsub/awssnssqs"
-	_ "gocloud.dev/pubsub/azuresb"
+	// _ "gocloud.dev/pubsub/azuresb"
 	_ "gocloud.dev/pubsub/gcppubsub"
 	_ "gocloud.dev/pubsub/natspubsub"
 	_ "gocloud.dev/pubsub/rabbitpubsub"
diff --git a/weed/server/master_grpc_server.go b/weed/server/master_grpc_server.go
index 1a17327a0..e0d1fd174 100644
--- a/weed/server/master_grpc_server.go
+++ b/weed/server/master_grpc_server.go
@@ -52,8 +52,9 @@ func (ms *MasterServer) SendHeartbeat(stream master_pb.Seaweed_SendHeartbeatServ
 			return err
 		}
 
+		t.Sequence.SetMax(heartbeat.MaxFileKey)
+
 		if dn == nil {
-			t.Sequence.SetMax(heartbeat.MaxFileKey)
 			if heartbeat.Ip == "" {
 				if pr, ok := peer.FromContext(stream.Context()); ok {
 					if pr.Addr != net.Addr(nil) {
diff --git a/weed/server/volume_grpc_batch_delete.go b/weed/server/volume_grpc_batch_delete.go
index d7fbb6edf..fdb7937d2 100644
--- a/weed/server/volume_grpc_batch_delete.go
+++ b/weed/server/volume_grpc_batch_delete.go
@@ -58,7 +58,7 @@ func (vs *VolumeServer) BatchDelete(ctx context.Context, req *volume_server_pb.B
 			break
 		}
 		n.LastModified = now
-		if size, err := vs.store.Delete(volumeId, n); err != nil {
+		if size, err := vs.store.DeleteVolumeNeedle(volumeId, n); err != nil {
 			resp.Results = append(resp.Results, &volume_server_pb.DeleteResult{
 				FileId: fid,
 				Status: http.StatusInternalServerError,
diff --git a/weed/server/volume_grpc_tail.go b/weed/server/volume_grpc_tail.go
index 698bad5b8..34c55a599 100644
--- a/weed/server/volume_grpc_tail.go
+++ b/weed/server/volume_grpc_tail.go
@@ -110,7 +110,7 @@ func (vs *VolumeServer) VolumeTailReceiver(ctx context.Context, req *volume_serv
 	defer glog.V(1).Infof("receive tailing volume %d finished", v.Id)
 
 	return resp, operation.TailVolumeFromSource(req.SourceVolumeServer, vs.grpcDialOption, v.Id, req.SinceNs, int(req.IdleTimeoutSeconds), func(n *needle.Needle) error {
-		_, _, err := vs.store.Write(v.Id, n)
+		_, _, err := vs.store.WriteVolumeNeedle(v.Id, n)
 		return err
 	})
 
diff --git a/weed/storage/erasure_coding/ec_shard.go b/weed/storage/erasure_coding/ec_shard.go
index b280157b8..47e6d3d1e 100644
--- a/weed/storage/erasure_coding/ec_shard.go
+++ b/weed/storage/erasure_coding/ec_shard.go
@@ -81,7 +81,7 @@ func (shard *EcVolumeShard) Close() {
 
 func (shard *EcVolumeShard) Destroy() {
 	os.Remove(shard.FileName() + ToExt(int(shard.ShardId)))
-	stats.VolumeServerVolumeCounter.WithLabelValues(shard.Collection, "ec_shards").Inc()
+	stats.VolumeServerVolumeCounter.WithLabelValues(shard.Collection, "ec_shards").Dec()
 }
 
 func (shard *EcVolumeShard) ReadAt(buf []byte, offset int64) (int, error) {
diff --git a/weed/storage/store.go b/weed/storage/store.go
index d2dd76d52..e99d77774 100644
--- a/weed/storage/store.go
+++ b/weed/storage/store.go
@@ -211,7 +211,7 @@ func (s *Store) Close() {
 	}
 }
 
-func (s *Store) Write(i needle.VolumeId, n *needle.Needle) (size uint32, isUnchanged bool, err error) {
+func (s *Store) WriteVolumeNeedle(i needle.VolumeId, n *needle.Needle) (size uint32, isUnchanged bool, err error) {
 	if v := s.findVolume(i); v != nil {
 		if v.readOnly {
 			err = fmt.Errorf("volume %d is read only", i)
@@ -230,7 +230,7 @@ func (s *Store) Write(i needle.VolumeId, n *needle.Needle) (size uint32, isUncha
 	return
 }
 
-func (s *Store) Delete(i needle.VolumeId, n *needle.Needle) (uint32, error) {
+func (s *Store) DeleteVolumeNeedle(i needle.VolumeId, n *needle.Needle) (uint32, error) {
 	if v := s.findVolume(i); v != nil && !v.readOnly {
 		return v.deleteNeedle(n)
 	}
diff --git a/weed/storage/volume_read_write.go b/weed/storage/volume_read_write.go
index 93ce1eab9..0327e5a1f 100644
--- a/weed/storage/volume_read_write.go
+++ b/weed/storage/volume_read_write.go
@@ -96,13 +96,29 @@ func (v *Volume) writeNeedle(n *needle.Needle) (offset uint64, size uint32, isUn
 		n.Ttl = v.Ttl
 	}
 
+	// check whether existing needle cookie matches
+	nv, ok := v.nm.Get(n.Id)
+	if ok {
+		existingNeedle, _, _, existingNeedleReadErr := needle.ReadNeedleHeader(v.dataFile, v.Version(), nv.Offset.ToAcutalOffset())
+		if existingNeedleReadErr != nil {
+			err = fmt.Errorf("reading existing needle: %v", existingNeedleReadErr)
+			return
+		}
+		if existingNeedle.Cookie != n.Cookie {
+			glog.V(0).Infof("write cookie mismatch: existing %x, new %x", existingNeedle.Cookie, n.Cookie)
+			err = fmt.Errorf("mismatching cookie %x", n.Cookie)
+			return
+		}
+	}
+
+	// append to dat file
 	n.AppendAtNs = uint64(time.Now().UnixNano())
 	if offset, size, _, err = n.Append(v.dataFile, v.Version()); err != nil {
 		return
 	}
 	v.lastAppendAtNs = n.AppendAtNs
 
-	nv, ok := v.nm.Get(n.Id)
+	// add to needle map
 	if !ok || uint64(nv.Offset.ToAcutalOffset()) < offset {
 		if err = v.nm.Put(n.Id, ToOffset(int64(offset)), n.Size); err != nil {
 			glog.V(4).Infof("failed to save in needle map %d: %v", n.Id, err)
@@ -224,6 +240,7 @@ func ScanVolumeFileFrom(version needle.Version, dataFile *os.File, offset int64,
 		}
 		if err != nil {
 			glog.V(0).Infof("visit needle error: %v", err)
+			return fmt.Errorf("visit needle error: %v", err)
 		}
 		offset += NeedleHeaderSize + rest
 		glog.V(4).Infof("==> new entry offset %d", offset)
diff --git a/weed/storage/volume_vacuum.go b/weed/storage/volume_vacuum.go
index cc7c7d6e6..3bb306649 100644
--- a/weed/storage/volume_vacuum.go
+++ b/weed/storage/volume_vacuum.go
@@ -53,7 +53,7 @@ func (v *Volume) CommitCompact() error {
 		glog.V(0).Infof("fail to close volume %d", v.Id)
 	}
 	v.dataFile = nil
-	stats.VolumeServerVolumeCounter.WithLabelValues(v.Collection, "volume").Inc()
+	stats.VolumeServerVolumeCounter.WithLabelValues(v.Collection, "volume").Dec()
 
 	var e error
 	if e = v.makeupDiff(v.FileName()+".cpd", v.FileName()+".cpx", v.FileName()+".dat", v.FileName()+".idx"); e != nil {
diff --git a/weed/topology/store_replicate.go b/weed/topology/store_replicate.go
index d4076d548..d21c4d210 100644
--- a/weed/topology/store_replicate.go
+++ b/weed/topology/store_replicate.go
@@ -25,7 +25,7 @@ func ReplicatedWrite(masterNode string, s *storage.Store,
 	//check JWT
 	jwt := security.GetJwt(r)
 
-	size, isUnchanged, err = s.Write(volumeId, n)
+	size, isUnchanged, err = s.WriteVolumeNeedle(volumeId, n)
 	if err != nil {
 		err = fmt.Errorf("failed to write to local disk: %v", err)
 		return
@@ -89,7 +89,7 @@ func ReplicatedDelete(masterNode string, store *storage.Store,
 	//check JWT
 	jwt := security.GetJwt(r)
 
-	ret, err := store.Delete(volumeId, n)
+	ret, err := store.DeleteVolumeNeedle(volumeId, n)
 	if err != nil {
 		glog.V(0).Infoln("delete error:", err)
 		return ret, err