diff --git a/tests/script/unique/arbitrator/dn3_mn1_replica_change.sim b/tests/script/unique/arbitrator/dn3_mn1_replica_change.sim
new file mode 100644
index 0000000000..f34322a255
--- /dev/null
+++ b/tests/script/unique/arbitrator/dn3_mn1_replica_change.sim
@@ -0,0 +1,413 @@
+system sh/stop_dnodes.sh
+system sh/deploy.sh -n dnode1 -i 1
+system sh/deploy.sh -n dnode2 -i 2
+system sh/deploy.sh -n dnode3 -i 3
+system sh/deploy.sh -n dnode4 -i 4
+
+system sh/cfg.sh -n dnode1 -c numOfMPeers -v 1
+system sh/cfg.sh -n dnode2 -c numOfMPeers -v 1
+system sh/cfg.sh -n dnode3 -c numOfMPeers -v 1
+
+system sh/cfg.sh -n dnode1 -c walLevel -v 2
+system sh/cfg.sh -n dnode2 -c walLevel -v 2
+system sh/cfg.sh -n dnode3 -c walLevel -v 2
+system sh/cfg.sh -n dnode4 -c walLevel -v 2
+
+system sh/cfg.sh -n dnode1 -c balanceInterval -v 10
+system sh/cfg.sh -n dnode2 -c balanceInterval -v 10
+system sh/cfg.sh -n dnode3 -c balanceInterval -v 10
+system sh/cfg.sh -n dnode4 -c balanceInterval -v 10
+
+system sh/cfg.sh -n dnode1 -c numOfTotalVnodes -v 4
+system sh/cfg.sh -n dnode2 -c numOfTotalVnodes -v 4
+system sh/cfg.sh -n dnode3 -c numOfTotalVnodes -v 4
+system sh/cfg.sh -n dnode4 -c numOfTotalVnodes -v 4
+
+system sh/cfg.sh -n dnode1 -c alternativeRole -v 1
+system sh/cfg.sh -n dnode2 -c alternativeRole -v 2
+system sh/cfg.sh -n dnode3 -c alternativeRole -v 2
+system sh/cfg.sh -n dnode4 -c alternativeRole -v 2
+
+system sh/cfg.sh -n dnode1 -c numOfTotalVnodes -v 4
+system sh/cfg.sh -n dnode2 -c numOfTotalVnodes -v 4
+system sh/cfg.sh -n dnode3 -c numOfTotalVnodes -v 4
+system sh/cfg.sh -n dnode4 -c numOfTotalVnodes -v 4
+
+system sh/cfg.sh -n dnode1 -c maxtablesPerVnode -v 4
+system sh/cfg.sh -n dnode2 -c maxtablesPerVnode -v 4
+system sh/cfg.sh -n dnode3 -c maxtablesPerVnode -v 4
+system sh/cfg.sh -n dnode4 -c maxtablesPerVnode -v 4
+system sh/cfg.sh -n dnode5 -c maxtablesPerVnode -v 4
+
+system sh/cfg.sh -n dnode1 -c arbitrator -v $arbitrator
+system sh/cfg.sh -n dnode2 -c arbitrator -v $arbitrator
+system sh/cfg.sh -n dnode3 -c arbitrator -v $arbitrator
+
+print ============== step0: start tarbitrator
+system sh/exec_tarbitrator.sh -s start
+
+print ============== step1: start dnode1, only deploy mnode
+system sh/exec.sh -n dnode1 -s start
+sleep 3000
+sql connect
+
+print ============== step2: start dnode2 and add into cluster , then create database with replica 1, and create table, insert data
+system sh/exec.sh -n dnode2 -s start
+sql create dnode $hostname2
+sleep 3000
+
+$totalTableNum = 10000
+$sleepTimer = 10000
+
+$db = db
+sql create database $db replica 1 maxTables $totalTableNum
+sql use $db
+
+# create table , insert data
+$stb = stb
+sql create table $stb (ts timestamp, c1 int) tags(t1 int)
+$rowNum = 100
+$tblNum = $totalTableNum
+$totalRows = 0
+$tsStart = 1420041600000
+
+$i = 0
+while $i < $tblNum
+  $tb = tb . $i
+  sql create table $tb using $stb tags( $i )
+ 
+  $x = 0
+  while $x < $rowNum
+    $ts = $tsStart + $x
+    sql insert into $tb values ( $ts + 0a , $x ) ( $ts + 1a , $x ) ( $ts + 2a , $x ) ( $ts + 3a , $x ) ( $ts + 4a , $x ) ( $ts + 5a , $x ) ( $ts + 6a , $x ) ( $ts + 7a , $x ) ( $ts + 8a , $x ) ( $ts + 9a , $x ) ( $ts + 10a , $x ) ( $ts + 11a , $x ) ( $ts + 12a , $x ) ( $ts + 13a , $x ) ( $ts + 14a , $x ) ( $ts + 15a , $x ) ( $ts + 16a , $x ) ( $ts + 17a , $x ) ( $ts + 18a , $x ) ( $ts + 19a , $x ) ( $ts + 20a , $x ) ( $ts + 21a , $x ) ( $ts + 22a , $x ) ( $ts + 23a , $x ) ( $ts + 24a , $x ) ( $ts + 25a , $x ) ( $ts + 26a , $x ) ( $ts + 27a , $x ) ( $ts + 28a , $x ) ( $ts + 29a , $x ) ( $ts + 30a , $x ) ( $ts + 31a , $x ) ( $ts + 32a , $x ) ( $ts + 33a , $x ) ( $ts + 34a , $x ) ( $ts + 25a , $x ) ( $ts + 26a , $x ) ( $ts + 27a , $x ) ( $ts + 28a , $x ) ( $ts + 29a , $x ) ( $ts + 30a , $x ) ( $ts + 31a , $x ) ( $ts + 32a , $x ) ( $ts + 33a , $x ) ( $ts + 34a , $x ) ( $ts + 35a , $x ) ( $ts + 36a , $x ) ( $ts + 37a , $x ) ( $ts + 38a , $x ) ( $ts + 39a , $x ) ( $ts + 40a , $x ) ( $ts + 41a , $x ) ( $ts + 42a , $x ) ( $ts + 43a , $x ) ( $ts + 44a , $x ) ( $ts + 45a , $x ) ( $ts + 46a , $x ) ( $ts + 47a , $x ) ( $ts + 48a , $x ) ( $ts + 49a , $x ) ( $ts + 50a , $x ) ( $ts + 51a , $x ) ( $ts + 52a , $x ) ( $ts + 53a , $x ) ( $ts + 54a , $x ) ( $ts + 55a , $x ) ( $ts + 56a , $x ) ( $ts + 57a , $x ) ( $ts + 58a , $x ) ( $ts + 59a , $x ) 
+    $x = $x + 60
+  endw 
+  $totalRows = $totalRows + $x
+  print       info: inserted $x rows into $tb and totalRows: $totalRows
+  $i = $i + 1
+endw 
+
+sql select count(*) from $stb
+sleep 1000
+print data00 $data00
+if $data00 != $totalRows then
+	return -1
+endi
+
+print ============== step3: start dnode3 and add into cluster , then alter replica from 1 to 2, and waiting sync
+system sh/exec.sh -n dnode3 -s start
+sql create dnode $hostname3
+sleep 3000
+
+sql alter database $db replica 2
+sleep $sleepTimer
+
+wait_dnode3_ready:
+sql show dnodes
+if $rows != 3 then
+  sleep 2000
+  goto wait_dnode3_ready
+endi
+print $data0_1  $data1_1  $data2_1  $data3_1  $data4_1
+print $data0_2  $data1_2  $data2_2  $data3_2  $data4_2
+print $data0_3  $data1_3  $data2_3  $data3_3  $data4_3
+#print $data0_4  $data1_4  $data2_4  $data3_4  $data4_4
+#print $data0_5  $data1_5  $data2_5  $data3_5  $data4_5
+#print $data0_6  $data1_6  $data2_6  $data3_6  $data4_6
+#$dnode1Status = $data4_1  
+$dnode2Status = $data4_2
+$dnode3Status = $data4_3  
+#$dnode4Status = $data4_4 
+#$dnode5Status = $data4_5
+
+if $dnode2Status != ready then
+  sleep 2000
+  goto wait_dnode3_ready
+endi
+if $dnode3Status != ready then
+  sleep 2000
+  goto wait_dnode3_ready
+endi
+
+sleep $sleepTimer
+# check using select
+sql select count(*) from $stb
+print data00 $data00
+if $data00 != $totalRows then
+	return -1
+endi
+
+
+print ============== step4: stop dnode2 for checking if sync success
+system sh/exec.sh -n dnode2 -s stop
+sleep $sleepTimer
+
+wait_dnode2_offline:
+sql show dnodes
+if $rows != 3 then
+  sleep 2000
+  goto wait_dnode2_offline
+endi
+print $data0_1  $data1_1  $data2_1  $data3_1  $data4_1
+print $data0_2  $data1_2  $data2_2  $data3_2  $data4_2
+print $data0_3  $data1_3  $data2_3  $data3_3  $data4_3
+#print $data0_4  $data1_4  $data2_4  $data3_4  $data4_4
+#print $data0_5  $data1_5  $data2_5  $data3_5  $data4_5
+#print $data0_6  $data1_6  $data2_6  $data3_6  $data4_6
+#$dnode1Status = $data4_1  
+$dnode2Status = $data4_2
+$dnode3Status = $data4_3  
+#$dnode4Status = $data4_4 
+#$dnode5Status = $data4_5
+
+if $dnode2Status != offline then
+  sleep 2000
+  goto wait_dnode2_offline
+endi
+if $dnode3Status != ready then
+  sleep 2000
+  goto wait_dnode2_offline
+endi
+
+sleep $sleepTimer   # waitting for move master vnode of dnode2 to dnode3
+# check using select
+sql select count(*) from $stb
+print data00 $data00
+if $data00 != $totalRows then
+	return -1
+endi
+
+print ============== step5: restart dnode2
+system sh/exec.sh -n dnode2 -s start
+sleep 3000
+
+wait_dnode2_ready:
+sql show dnodes
+if $rows != 3 then
+  sleep 2000
+  goto wait_dnode2_ready
+endi
+print $data0_1  $data1_1  $data2_1  $data3_1  $data4_1
+print $data0_2  $data1_2  $data2_2  $data3_2  $data4_2
+print $data0_3  $data1_3  $data2_3  $data3_3  $data4_3
+#print $data0_4  $data1_4  $data2_4  $data3_4  $data4_4
+#print $data0_5  $data1_5  $data2_5  $data3_5  $data4_5
+#print $data0_6  $data1_6  $data2_6  $data3_6  $data4_6
+#$dnode1Status = $data4_1  
+$dnode2Status = $data4_2
+$dnode3Status = $data4_3  
+#$dnode4Status = $data4_4 
+#$dnode5Status = $data4_5
+
+if $dnode2Status != ready then
+  sleep 2000
+  goto wait_dnode2_ready
+endi
+
+sleep $sleepTimer
+# check using select
+sql select count(*) from $stb
+print data00 $data00
+if $data00 != $totalRows then
+	return -1
+endi
+
+print ============== step6: start dnode4 and add into cluster , then alter replica from 2 to 3, and waiting sync
+system sh/exec.sh -n dnode4 -s start
+sql create dnode $hostname4
+sleep 3000
+
+sql alter database $db replica 3
+sleep $sleepTimer
+
+wait_dnode4_ready:
+sql show dnodes
+if $rows != 4 then
+  sleep 2000
+  goto wait_dnode4_ready
+endi
+print $data0_1  $data1_1  $data2_1  $data3_1  $data4_1
+print $data0_2  $data1_2  $data2_2  $data3_2  $data4_2
+print $data0_3  $data1_3  $data2_3  $data3_3  $data4_3
+print $data0_4  $data1_4  $data2_4  $data3_4  $data4_4
+#print $data0_5  $data1_5  $data2_5  $data3_5  $data4_5
+#print $data0_6  $data1_6  $data2_6  $data3_6  $data4_6
+#$dnode1Status = $data4_1  
+#$dnode2Status = $data4_2
+$dnode3Status = $data4_3  
+$dnode4Status = $data4_4 
+#$dnode5Status = $data4_5
+
+if $dnode4Status != ready then
+  sleep 2000
+  goto wait_dnode4_ready
+endi
+
+sleep $sleepTimer
+# check using select
+sql select count(*) from $stb
+print data00 $data00
+if $data00 != $totalRows then
+	return -1
+endi
+
+print ============== step7: alter replica from 3 to 2, and waiting sync
+sql alter database $db replica 2
+sleep $sleepTimer
+
+wait_vgroups_replic_to_2:
+sql show vgroups
+print $data0_1  $data1_1  $data2_1  $data3_1  $data4_1  $data5_1  $data6_1  $data7_1  $data8_1
+print $data0_2  $data1_2  $data2_2  $data3_2  $data4_2  $data5_2  $data6_2  $data7_2  $data8_2
+print $data0_3  $data1_3  $data2_3  $data3_3  $data4_3  $data5_3  $data6_3  $data7_3  $data8_3
+print $data0_4  $data1_4  $data2_4  $data3_4  $data4_4  $data5_4  $data6_4  $data7_4  $data8_4
+#print $data0_5  $data1_5  $data2_5  $data3_5  $data4_5
+#print $data0_6  $data1_6  $data2_6  $data3_6  $data4_6
+$thirdDnode_2 = $data8_1 
+$thirdDnode_3 = $data8_2 
+$thirdDnode_4 = $data8_3 
+$thirdDnode_5 = $data8_4 
+
+if $thirdDnode_2 != null then
+  sleep 2000
+  goto wait_vgroups_replic_to_2
+endi
+if $thirdDnode_3 != null then
+  sleep 2000
+  goto wait_vgroups_replic_to_2
+endi
+if $thirdDnode_4 != null then
+  sleep 2000
+  goto wait_vgroups_replic_to_2
+endi
+if $thirdDnode_5 != null then
+  sleep 2000
+  goto wait_vgroups_replic_to_2
+endi
+
+sleep $sleepTimer  #waiting del one replica data
+# check using select
+sql select count(*) from $stb
+print data00 $data00
+if $data00 != $totalRows then
+	return -1
+endi
+
+print ============== step8: alter replica from 2 to 1, and waiting sync
+sql alter database $db replica 1
+sleep $sleepTimer
+
+wait_vgroups_replic_to_1:
+sql show vgroups
+print $data0_1  $data1_1  $data2_1  $data3_1  $data4_1  $data5_1  $data6_1  $data7_1  $data8_1
+print $data0_2  $data1_2  $data2_2  $data3_2  $data4_2  $data5_2  $data6_2  $data7_2  $data8_2
+print $data0_3  $data1_3  $data2_3  $data3_3  $data4_3  $data5_3  $data6_3  $data7_3  $data8_3
+print $data0_4  $data1_4  $data2_4  $data3_4  $data4_4  $data5_4  $data6_4  $data7_4  $data8_4
+#print $data0_5  $data1_5  $data2_5  $data3_5  $data4_5
+#print $data0_6  $data1_6  $data2_6  $data3_6  $data4_6
+$sencodDnode_2 = $data5_1 
+$sencodDnode_3 = $data5_2 
+$sencodDnode_4 = $data5_3 
+$sencodDnode_5 = $data5_4 
+
+if $sencodDnode_2 != null then
+  sleep 2000
+  goto wait_vgroups_replic_to_1
+endi
+if $sencodDnode_3 != null then
+  sleep 2000
+  goto wait_vgroups_replic_to_1
+endi
+if $sencodDnode_4 != null then
+  sleep 2000
+  goto wait_vgroups_replic_to_1
+endi
+if $sencodDnode_5 != null then
+  sleep 2000
+  goto wait_vgroups_replic_to_1
+endi
+
+all_dnodes_ready:
+sql show dnodes
+if $rows != 4 then
+  sleep 2000
+  goto all_dnodes_ready
+endi
+print $data0_1  $data1_1  $data2_1  $data3_1  $data4_1
+print $data0_2  $data1_2  $data2_2  $data3_2  $data4_2
+print $data0_3  $data1_3  $data2_3  $data3_3  $data4_3
+print $data0_4  $data1_4  $data2_4  $data3_4  $data4_4
+#print $data0_5  $data1_5  $data2_5  $data3_5  $data4_5
+#print $data0_6  $data1_6  $data2_6  $data3_6  $data4_6
+$dnode1Status = $data4_1  
+$dnode2Status = $data4_2
+$dnode3Status = $data4_3  
+$dnode4Status = $data4_4 
+#$dnode5Status = $data4_5
+
+if $dnode1Status != ready then
+  sleep 2000
+  goto all_dnodes_ready
+endi
+if $dnode2Status != ready then
+  sleep 2000
+  goto all_dnodes_ready
+endi
+if $dnode3Status != ready then
+  sleep 2000
+  goto all_dnodes_ready
+endi
+if $dnode4Status != ready then
+  sleep 2000
+  goto all_dnodes_ready
+endi
+
+sleep $sleepTimer  #waiting del one replica data
+# check using select
+sql select count(*) from $stb
+print data00 $data00
+if $data00 != $totalRows then
+	return -1
+endi
+
+print ============== step9: drop dnode2/dnode3
+sql drop dnode $hostname2
+sql drop dnode $hostname3
+sleep $sleepTimer
+
+wait_dnode23_dropped:
+sql show dnodes
+if $rows != 2 then
+  sleep 2000
+  goto wait_dnode23_dropped
+endi
+print $data0_1  $data1_1  $data2_1  $data3_1  $data4_1
+print $data0_2  $data1_2  $data2_2  $data3_2  $data4_2
+print $data0_3  $data1_3  $data2_3  $data3_3  $data4_3
+print $data0_4  $data1_4  $data2_4  $data3_4  $data4_4
+#print $data0_5  $data1_5  $data2_5  $data3_5  $data4_5
+#print $data0_6  $data1_6  $data2_6  $data3_6  $data4_6
+$dnode1Status = $data4_1  
+$dnode2Status = $data4_2
+$dnode3Status = $data4_3  
+$dnode4Status = $data4_4 
+
+if $dnode2Status != null then
+  sleep 2000
+  goto wait_dnode23_dropped
+endi
+if $dnode3Status != null then
+  sleep 2000
+  goto wait_dnode23_dropped
+endi
+if $dnode4Status != ready then
+  return -1
+endi
+
+sleep $sleepTimer  #waiting move vnode from dnode3/dnode3 to dnode4
+# check using select
+sql select count(*) from $stb
+print data00 $data00
+if $data00 != $totalRows then
+	return -1
+endi