HDFS-7772. Document hdfs balancer -exclude/-include option in HDFSCommands.html. Contributed by Xiaoyu Yao.

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -653,6 +653,9 @@ Release 2.7.0 - UNRELEASED
     HDFS-7804. correct the haadmin command usage in #HDFSHighAvailabilityWithQJM.html
     (Brahma Reddy Battula via umamahesh)
 
+    HDFS-7772. Document hdfs balancer -exclude/-include option in
+    HDFSCommands.html (Xiaoyu Yao via cnauroth)
+
   OPTIMIZATIONS
 
     HDFS-7454. Reduce memory footprint for AclEntries in NameNode.

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/balancer/Balancer.java

@@ -170,15 +170,14 @@ public class Balancer {
   private static final long GB = 1L << 30; //1GB
   private static final long MAX_SIZE_TO_MOVE = 10*GB;
 
-  private static final String USAGE = "Usage: java "
-      + Balancer.class.getSimpleName()
+  private static final String USAGE = "Usage: hdfs balancer"
       + "\n\t[-policy <policy>]\tthe balancing policy: "
       + BalancingPolicy.Node.INSTANCE.getName() + " or "
       + BalancingPolicy.Pool.INSTANCE.getName()
       + "\n\t[-threshold <threshold>]\tPercentage of disk capacity"
-      + "\n\t[-exclude [-f <hosts-file> | comma-sperated list of hosts]]"
+      + "\n\t[-exclude [-f <hosts-file> | <comma-separated list of hosts>]]"
       + "\tExcludes the specified datanodes."
-      + "\n\t[-include [-f <hosts-file> | comma-sperated list of hosts]]"
+      + "\n\t[-include [-f <hosts-file> | <comma-separated list of hosts>]]"
       + "\tIncludes only the specified datanodes."
       + "\n\t[-idleiterations <idleiterations>]"
       + "\tNumber of consecutive idle iterations (-1 for Infinite) before exit.";

hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSCommands.md

@@ -245,13 +245,22 @@ Commands useful for administrators of a hadoop cluster.
 
 ### `balancer`
 
-Usage: `hdfs balancer [-threshold <threshold>] [-policy <policy>] [-idleiterations <idleiterations>]`
+Usage:
+
+        hdfs balancer
+              [-threshold <threshold>]
+              [-policy <policy>]
+              [-exclude [-f <hosts-file> | <comma-separated list of hosts>]]
+              [-include [-f <hosts-file> | <comma-separated list of hosts>]]
+              [-idleiterations <idleiterations>]
 
 | COMMAND\_OPTION | Description |
 |:---- |:---- |
-| `-policy` *policy* | `datanode` (default): Cluster is balanced if each datanode is balanced.<br/> `blockpool`: Cluster is balanced if each block pool in each datanode is balanced. |
-| `-threshold` *threshold* | Percentage of disk capacity. This overwrites the default threshold. |
-| `-idleiterations` *iterations* | Maximum number of idle iterations before exit. This overwrites the default idleiterations(5). |
+| `-policy` \<policy\> | `datanode` (default): Cluster is balanced if each datanode is balanced.<br/> `blockpool`: Cluster is balanced if each block pool in each datanode is balanced. |
+| `-threshold` \<threshold\> | Percentage of disk capacity. This overwrites the default threshold. |
+| `-exclude -f` \<hosts-file\> \| \<comma-separated list of hosts\> | Excludes the specified datanodes from being balanced by the balancer. |
+| `-include -f` \<hosts-file\> \| \<comma-separated list of hosts\> | Includes only the specified datanodes to be balanced by the balancer. |
+| `-idleiterations` \<iterations\> | Maximum number of idle iterations before exit. This overwrites the default idleiterations(5). |
 
 Runs a cluster balancing utility. An administrator can simply press Ctrl-C to stop the rebalancing process. See [Balancer](./HdfsUserGuide.html#Balancer) for more details.