HDFS-6530. Fix Balancer documentation.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1603571 13f79535-47bb-0310-9956-ffa450edef68

hadoop-common-project/hadoop-common/src/site/apt/CommandsManual.apt.vm

@@ -306,9 +306,9 @@ Administration Commands
 
    Runs a cluster balancing utility. An administrator can simply press Ctrl-C
    to stop the rebalancing process. See
-   {{{../hadoop-hdfs/HdfsUserGuide.html#Rebalancer}Rebalancer}} for more details.
+   {{{../hadoop-hdfs/HdfsUserGuide.html#Balancer}Balancer}} for more details.
 
-   Usage: <<<hadoop balancer [-threshold <threshold>]>>>
+   Usage: <<<hadoop balancer [-threshold <threshold>] [-policy <policy>]>>>
 
 *------------------------+-----------------------------------------------------------+
 || COMMAND_OPTION        | Description
@@ -316,6 +316,11 @@ Administration Commands
 | -threshold <threshold> | Percentage of disk capacity. This overwrites the
                          | default threshold.
 *------------------------+-----------------------------------------------------------+
+| -policy <policy>       | <<<datanode>>> (default): Cluster is balanced if each datanode is balanced. \
+                         | <<<blockpool>>>: Cluster is balanced if each block pool in each datanode is balanced.
+*------------------------+-----------------------------------------------------------+
+
+   Note that the <<<blockpool>>> policy is more strict than the <<<datanode>>> policy.
 
 * <<<daemonlog>>>
 

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

@@ -452,6 +452,8 @@ Release 2.5.0 - UNRELEASED
     HDFS-6545. Finalizing rolling upgrade can make NN unavailable for a long
     duration. (kihwal)
 
+    HDFS-6530. Fix Balancer documentation.  (szetszwo)
+
   OPTIMIZATIONS
 
     HDFS-6214. Webhdfs has poor throughput for files >2GB (daryn)

hadoop-hdfs-project/hadoop-hdfs/src/site/apt/Federation.apt.vm

@@ -287,13 +287,14 @@ HDFS Federation
 
   Policy could be:
 
-  * <<<node>>> - this is the <default> policy. This balances the storage at 
+  * <<<datanode>>> - this is the <default> policy. This balances the storage at 
     the datanode level. This is similar to balancing policy from prior releases.
 
   * <<<blockpool>>> - this balances the storage at the block pool level. 
     Balancing at block pool level balances storage at the datanode level also.
 
-  Note that Balander only balances the data and does not balance the namespace.
+  Note that Balancer only balances the data and does not balance the namespace.
+  For the complete command usage, see {{{../hadoop-common/CommandsManual.html#balancer}balancer}}.
 
 ** Decommissioning
 

hadoop-hdfs-project/hadoop-hdfs/src/site/apt/HdfsUserGuide.apt.vm

@@ -77,7 +77,7 @@ HDFS Users Guide
           * <<<fetchdt>>>: a utility to fetch DelegationToken and store it in a
             file on the local system.
 
-          * Rebalancer: tool to balance the cluster when the data is
+          * Balancer: tool to balance the cluster when the data is
             unevenly distributed among DataNodes.
 
           * Upgrade and rollback: after a software upgrade, it is possible
@@ -316,7 +316,7 @@ HDFS Users Guide
 
    For command usage, see {{{../hadoop-common/CommandsManual.html#namenode}namenode}}.
 
-* Rebalancer
+* Balancer
 
    HDFS data might not always be be placed uniformly across the DataNode.
    One common reason is addition of new DataNodes to an existing cluster.
@@ -338,7 +338,7 @@ HDFS Users Guide
    Due to multiple competing considerations, data might not be uniformly
    placed across the DataNodes. HDFS provides a tool for administrators
    that analyzes block placement and rebalanaces data across the DataNode.
-   A brief administrator's guide for rebalancer as a PDF is attached to
+   A brief administrator's guide for balancer is available at 
    {{{https://issues.apache.org/jira/browse/HADOOP-1652}HADOOP-1652}}.
 
    For command usage, see {{{../hadoop-common/CommandsManual.html#balancer}balancer}}.