From 9639f37ee21427303e877e8aeb486e0d71982e0f Mon Sep 17 00:00:00 2001
From: Harsh J <harsh@apache.org>
Date: Sun, 27 Jan 2013 17:42:25 +0000
Subject: [PATCH] HDFS-4259. Improve pipeline DN replacement failure message.
 Contributed by Harsh J. (harsh)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1439126 13f79535-47bb-0310-9956-ffa450edef68
---
 hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt   |  2 ++
 .../apache/hadoop/hdfs/DFSOutputStream.java   | 19 ++++++++++++-------
 2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index b9d908ab0e6..ee6b4040d49 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -497,6 +497,8 @@ Release 2.0.3-alpha - Unreleased
     HDFS-4403. DFSClient can infer checksum type when not provided by reading
     first byte (todd)
 
+    HDFS-4259. Improve pipeline DN replacement failure message (harsh)
+
   OPTIMIZATIONS
 
     HDFS-3429. DataNode reads checksums even if client does not need them (todd)
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSOutputStream.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSOutputStream.java
index 7245f8ac909..3232b1234a6 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSOutputStream.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSOutputStream.java
@@ -785,13 +785,18 @@ public class DFSOutputStream extends FSOutputSummer implements Syncable {
     private int findNewDatanode(final DatanodeInfo[] original
         ) throws IOException {
       if (nodes.length != original.length + 1) {
-        throw new IOException("Failed to add a datanode.  "
-            + "User may turn off this feature by setting "
-            + DFSConfigKeys.DFS_CLIENT_WRITE_REPLACE_DATANODE_ON_FAILURE_POLICY_KEY
-            + " in configuration, where the current policy is "
-            + dfsClient.dtpReplaceDatanodeOnFailure
-            + ".  (Nodes: current=" + Arrays.asList(nodes)
-            + ", original=" + Arrays.asList(original) + ")");
+        throw new IOException(
+            new StringBuilder()
+            .append("Failed to replace a bad datanode on the existing pipeline ")
+            .append("due to no more good datanodes being available to try. ")
+            .append("(Nodes: current=").append(Arrays.asList(nodes))
+            .append(", original=").append(Arrays.asList(original)).append("). ")
+            .append("The current failed datanode replacement policy is ")
+            .append(dfsClient.dtpReplaceDatanodeOnFailure).append(", and ")
+            .append("a client may configure this via '")
+            .append(DFSConfigKeys.DFS_CLIENT_WRITE_REPLACE_DATANODE_ON_FAILURE_POLICY_KEY)
+            .append("' in its configuration.")
+            .toString());
       }
       for(int i = 0; i < nodes.length; i++) {
         int j = 0;