MAPREDUCE-883. harchive: Document how to unarchive (Akira AJISAKA and Koji Noguchi via aw)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1617977 13f79535-47bb-0310-9956-ffa450edef68

hadoop-mapreduce-project/CHANGES.txt

@@ -86,6 +86,9 @@ Trunk (Unreleased)
     MAPREDUCE-6019. MapReduce changes for exposing YARN/MR endpoints on multiple
     interfaces. (Craig Welch, Milan Potocnik, Arpit Agarwal via xgong)
 
+    MAPREDUCE-883. harchive: Document how to unarchive (Akira AJISAKA and
+      Koji Noguchi via aw)
+
   BUG FIXES
 
     MAPREDUCE-5714. Removed forceful JVM exit in shutDownJob.  

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/site/markdown/HadoopArchives.md.vm

@@ -20,6 +20,7 @@ Hadoop Archives Guide
  - [Overview](#Overview)
  - [How to Create an Archive](#How_to_Create_an_Archive)
  - [How to Look Up Files in Archives](#How_to_Look_Up_Files_in_Archives)
+ - [How to Unarchive an Archive](#How_to_Unarchive_an_Archive)
  - [Archives Examples](#Archives_Examples)
      - [Creating an Archive](#Creating_an_Archive)
      - [Looking Up Files](#Looking_Up_Files)
@@ -70,6 +71,20 @@ How to Look Up Files in Archives
 
   `har:///archivepath/fileinarchive`
 
+How to Unarchive an Archive
+---------------------------
+
+  Since all the fs shell commands in the archives work transparently,
+  unarchiving is just a matter of copying.
+
+  To unarchive sequentially:
+
+  `hdfs dfs -cp har:///user/zoo/foo.har/dir1 hdfs:/user/zoo/newdir`
+
+  To unarchive in parallel, use DistCp:
+
+  `hadoop distcp har:///user/zoo/foo.har/dir1 hdfs:/user/zoo/newdir`
+
 Archives Examples
 -----------------