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From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Update of "Hbase/FAQ_Operations" by DougMeil
Date Sat, 06 Aug 2011 19:31:36 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Hadoop Wiki" for change notification.

The "Hbase/FAQ_Operations" page has been changed by DougMeil:
http://wiki.apache.org/hadoop/Hbase/FAQ_Operations?action=diff&rev1=2&rev2=3

   1. [[#1|Can I fix OutOfMemoryExceptions in hbase?]]
   1. [[#2|How do I enable hbase DEBUG-level logging?]]
   1. [[#3|Why do I see "java.io.IOException...(Too many open files)" in my logs?]]
-  1. [[#4|What can I do to improve hbase performance?]]
-  1. [[#5|What ports does HBase use?]]
+  1. [[#4|What ports does HBase use?]]
-  1. [[#6|Why is HBase ignoring HDFS client configuration such as dfs.replication?]]
+  1. [[#5|Why is HBase ignoring HDFS client configuration such as dfs.replication?]]
-  1. [[#7|Can I safely move the master from node A to node B?]]
+  1. [[#6|Can I safely move the master from node A to node B?]]
-  1. [[#8|Can I safely move the hbase rootdir in hdfs?]]
+  1. [[#7|Can I safely move the hbase rootdir in hdfs?]]
-  1. [[#9|How do I add/remove a node?]]
+  1. [[#8|How do I add/remove a node?]]
-  1. [[#10|Why do servers have start codes?]]
+  1. [[#9|Why do servers have start codes?]]
  
  == Answers ==
  
@@ -29, +28 @@

  
  See the Troubleshooting section in the HBase Book http://hbase.apache.org/book.html#trouble
  
- '''4. <<Anchor(4)>> What can I do to improve hbase performance?'''
- 
- See the Performance section in the HBase book http://hbase.apache.org/book.html#performance
- Also, see [[PerformanceTuning|Performance Tuning]] on the wiki home page
- 
- '''5. <<Anchor(5)>> What ports does HBase use?'''
+ '''4. <<Anchor(4)>> What ports does HBase use?'''
  
  Not counting the ports used by hadoop -- hdfs and mapreduce -- by default, hbase runs the
master and its informational http server at 60000 and 60010 respectively and regionservers
at 60020 and their informational http server at 60030.  ''${HBASE_HOME}/conf/hbase-default.xml''
lists the default values of all ports used.  Also check ''${HBASE_HOME}/conf/hbase-site.xml''
for site-specific overrides.
  
  
- '''6. <<Anchor(6)>> Why is HBase ignoring HDFS client configuration such as
dfs.replication?'''
+ '''5. <<Anchor(5)>> Why is HBase ignoring HDFS client configuration such as
dfs.replication?'''
  
  If you have made HDFS client configuration on your hadoop cluster, HBase will not see this
configuration unless you do one of the following:
  
@@ -49, +43 @@

  
  The first option is the better of the three since it avoids duplication.
  
- '''7. <<Anchor(7)>> Can I safely move the master from node A to node B?'''
+ '''6. <<Anchor(6)>> Can I safely move the master from node A to node B?'''
    Yes.  HBase must be shutdown.  Edit your hbase-site.xml configuration across the cluster
setting hbase.master to point at the new location.
  
- '''8. <<Anchor(8)>> Can I safely move the hbase rootdir in hdfs?'''
+ '''7. <<Anchor(7)>> Can I safely move the hbase rootdir in hdfs?'''
    Yes.  HBase must be down for the move.  After the move, update the hbase-site.xml across
the cluster and restart.
  
  
- '''9. <<Anchor(9)>> How do I add/remove a node?'''
+ '''8. <<Anchor(8)>> How do I add/remove a node?'''
  
  For removing nodes, see the section on decommissioning nodes in the HBase Book http://hbase.apache.org/book.html#decommission
  
@@ -71, +65 @@

  
  For Hadoop, use the same kind of script (starts with hadoop-*), their process names (datanode,
tasktracker), and edit the slaves file. Removing datanodes is tricky, please review the dfsadmin
command before doing it.
  
- '''10. <<Anchor(10)>> Why do servers have start codes?'''
+ '''9. <<Anchor(9)>> Why do servers have start codes?'''
  
  If a region server crashes and recovers, it cannot be given work until its lease times out.
If the lease is identified only by an IP address and port number, then that server can't do
any progress until the lease times out. A start code is added so that the restarted server
can begin doing work immediately upon recovery. For more, see https://issues.apache.org/jira/browse/HBASE-1156.
  

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