From c970f1d00525e4273075cff7406dcbd71305abd5 Mon Sep 17 00:00:00 2001
From: Kihwal Lee <kihwal@apache.org>
Date: Thu, 14 Apr 2016 12:45:47 -0500
Subject: [PATCH] HDFS-10280. Document new dfsadmin command -evictWriters.
 Contributed by Wei-Chiu Chuang.

---
 .../src/main/java/org/apache/hadoop/hdfs/tools/DFSAdmin.java  | 4 ++++
 .../hadoop-hdfs/src/site/markdown/HDFSCommands.md             | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/DFSAdmin.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/DFSAdmin.java
index a35246f38b5..08d3da5405c 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/DFSAdmin.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/DFSAdmin.java
@@ -427,6 +427,7 @@ public class DFSAdmin extends FsShell {
     "\t[-allowSnapshot <snapshotDir>]\n" +
     "\t[-disallowSnapshot <snapshotDir>]\n" +
     "\t[-shutdownDatanode <datanode_host:ipc_port> [upgrade]]\n" +
+    "\t[-evictWriters <datanode_host:ipc_port>]\n" +
     "\t[-getDatanodeInfo <datanode_host:ipc_port>]\n" +
     "\t[-metasave filename]\n" +
     "\t[-triggerBlockReport [-incremental] <datanode_host:ipc_port>]\n" +
@@ -1829,6 +1830,9 @@ public class DFSAdmin extends FsShell {
     } else if ("-shutdownDatanode".equals(cmd)) {
       System.err.println("Usage: hdfs dfsadmin"
           + " [-shutdownDatanode <datanode_host:ipc_port> [upgrade]]");
+    } else if ("-evictWriters".equals(cmd)) {
+      System.err.println("Usage: hdfs dfsadmin"
+          + " [-evictWriters <datanode_host:ipc_port>]");
     } else if ("-getDatanodeInfo".equals(cmd)) {
       System.err.println("Usage: hdfs dfsadmin"
           + " [-getDatanodeInfo <datanode_host:ipc_port>]");
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSCommands.md b/hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSCommands.md
index 035abd63187..a6c8b4c4c9a 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSCommands.md
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSCommands.md
@@ -385,6 +385,7 @@ Usage:
         hdfs dfsadmin [-allowSnapshot <snapshotDir>]
         hdfs dfsadmin [-disallowSnapshot <snapshotDir>]
         hdfs dfsadmin [-shutdownDatanode <datanode_host:ipc_port> [upgrade]]
+        hdfs dfsadmin [-evictWriters <datanode_host:ipc_port>]
         hdfs dfsadmin [-getDatanodeInfo <datanode_host:ipc_port>]
         hdfs dfsadmin [-metasave filename]
         hdfs dfsadmin [-triggerBlockReport [-incremental] <datanode_host:ipc_port>]
@@ -419,6 +420,7 @@ Usage:
 | `-allowSnapshot` \<snapshotDir\> | Allowing snapshots of a directory to be created. If the operation completes successfully, the directory becomes snapshottable. See the [HDFS Snapshot Documentation](./HdfsSnapshots.html) for more information. |
 | `-disallowSnapshot` \<snapshotDir\> | Disallowing snapshots of a directory to be created. All snapshots of the directory must be deleted before disallowing snapshots. See the [HDFS Snapshot Documentation](./HdfsSnapshots.html) for more information. |
 | `-shutdownDatanode` \<datanode\_host:ipc\_port\> [upgrade] | Submit a shutdown request for the given datanode. See [Rolling Upgrade document](./HdfsRollingUpgrade.html#dfsadmin_-shutdownDatanode) for the detail. |
+| `-evictWriters` \<datanode\_host:ipc\_port\> | Make the datanode evict all clients that are writing a block. This is useful if decommissioning is hung due to slow writers. |
 | `-getDatanodeInfo` \<datanode\_host:ipc\_port\> | Get the information about the given datanode. See [Rolling Upgrade document](./HdfsRollingUpgrade.html#dfsadmin_-getDatanodeInfo) for the detail. |
 | `-metasave` filename | Save Namenode's primary data structures to *filename* in the directory specified by hadoop.log.dir property. *filename* is overwritten if it exists. *filename* will contain one line for each of the following<br/>1. Datanodes heart beating with Namenode<br/>2. Blocks waiting to be replicated<br/>3. Blocks currently being replicated<br/>4. Blocks waiting to be deleted |
 | `-triggerBlockReport` `[-incremental]` \<datanode\_host:ipc\_port\> | Trigger a block report for the given datanode. If 'incremental' is specified, it will be otherwise, it will be a full block report. |