diff --git a/docs/usecases.rst b/docs/usecases.rst
index ed70f0015..ac0a2d0b3 100644
--- a/docs/usecases.rst
+++ b/docs/usecases.rst
@@ -60,20 +60,20 @@ Data Migration Example
 
 .. code-block:: bash
 
-    weed master -mdir="/tmp/mdata" -defaultReplication="001" -ip="localhost" -port=9334
-    weed volume -dir=/tmp/vol1/ -mserver="localhost:9334" -ip="localhost" -port=8081
-    weed volume -dir=/tmp/vol2/ -mserver="localhost:9334" -ip="localhost" -port=8082
-    weed volume -dir=/tmp/vol3/ -mserver="localhost:9334" -ip="localhost" -port=8083
+	weed master -mdir="/tmp/mdata" -defaultReplication="001" -ip="localhost" -port=9334
+	weed volume -dir=/tmp/vol1/ -mserver="localhost:9334" -ip="localhost" -port=8081
+	weed volume -dir=/tmp/vol2/ -mserver="localhost:9334" -ip="localhost" -port=8082
+	weed volume -dir=/tmp/vol3/ -mserver="localhost:9334" -ip="localhost" -port=8083
 
 .. code-block:: bash
 
-    ls vol1 vol2 vol3
-    vol1:
-    1.dat 1.idx 2.dat 2.idx 3.dat 3.idx 5.dat 5.idx
-    vol2:
-    2.dat 2.idx 3.dat 3.idx 4.dat 4.idx 6.dat 6.idx
-    vol3:
-    1.dat 1.idx 4.dat 4.idx 5.dat 5.idx 6.dat 6.idx
+	ls vol1 vol2 vol3
+	vol1:
+	1.dat 1.idx 2.dat 2.idx 3.dat 3.idx 5.dat 5.idx
+	vol2:
+	2.dat 2.idx 3.dat 3.idx 4.dat 4.idx 6.dat 6.idx
+	vol3:
+	1.dat 1.idx 4.dat 4.idx 5.dat 5.idx 6.dat 6.idx
 
 stop all of them
 
@@ -85,29 +85,29 @@ it can be checked by md5.
 
 .. code-block:: bash
 
-    md5 vol1/1.dat vol2/1.dat
-    MD5 (vol1/1.dat) = c1a49a0ee550b44fef9f8ae9e55215c7
-    MD5 (vol2/1.dat) = c1a49a0ee550b44fef9f8ae9e55215c7
-    md5 vol1/1.idx vol2/1.idx
-    MD5 (vol1/1.idx) = b9edc95795dfb3b0f9063c9cc9ba8095
-    MD5 (vol2/1.idx) = b9edc95795dfb3b0f9063c9cc9ba8095
+	md5 vol1/1.dat vol2/1.dat
+	MD5 (vol1/1.dat) = c1a49a0ee550b44fef9f8ae9e55215c7
+	MD5 (vol2/1.dat) = c1a49a0ee550b44fef9f8ae9e55215c7
+	md5 vol1/1.idx vol2/1.idx
+	MD5 (vol1/1.idx) = b9edc95795dfb3b0f9063c9cc9ba8095
+	MD5 (vol2/1.idx) = b9edc95795dfb3b0f9063c9cc9ba8095
 
 .. code-block:: bash
 
-    ls vol1 vol2 vol3
-    vol1:
-    1.dat 1.idx 2.dat 2.idx 3.dat 3.idx 4.dat 4.idx 5.dat 5.idx 6.dat 6.idx
-    vol2:
-    1.dat 1.idx 2.dat 2.idx 3.dat 3.idx 4.dat 4.idx 5.dat 5.idx 6.dat 6.idx
-    vol3:
+	ls vol1 vol2 vol3
+	vol1:
+	1.dat 1.idx 2.dat 2.idx 3.dat 3.idx 4.dat 4.idx 5.dat 5.idx 6.dat 6.idx
+	vol2:
+	1.dat 1.idx 2.dat 2.idx 3.dat 3.idx 4.dat 4.idx 5.dat 5.idx 6.dat 6.idx
+	vol3:
 
 start
 
 .. code-block:: bash
 
-    weed master -mdir="/tmp/mdata" -defaultReplication="001" -ip="localhost" -port=9334
-    weed volume -dir=/tmp/vol1/ -mserver="localhost:9334" -ip="localhost" -port=8081
-    weed volume -dir=/tmp/vol2/ -mserver="localhost:9334" -ip="localhost" -port=8082
+	weed master -mdir="/tmp/mdata" -defaultReplication="001" -ip="localhost" -port=9334
+	weed volume -dir=/tmp/vol1/ -mserver="localhost:9334" -ip="localhost" -port=8081
+	weed volume -dir=/tmp/vol2/ -mserver="localhost:9334" -ip="localhost" -port=8082
 
 so we finished moving data of localhost:8083 to localhost:8081/localhost:8082