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Posted to commits@hbase.apache.org by st...@apache.org on 2012/01/17 06:15:44 UTC
svn commit: r1232308 - /hbase/trunk/src/docbkx/configuration.xml
Author: stack
Date: Tue Jan 17 05:15:44 2012
New Revision: 1232308
URL: http://svn.apache.org/viewvc?rev=1232308&view=rev
Log:
Update version on hadoop versions to include note on hadoop 1.0.0
Modified:
hbase/trunk/src/docbkx/configuration.xml
Modified: hbase/trunk/src/docbkx/configuration.xml
URL: http://svn.apache.org/viewvc/hbase/trunk/src/docbkx/configuration.xml?rev=1232308&r1=1232307&r2=1232308&view=diff
==============================================================================
--- hbase/trunk/src/docbkx/configuration.xml (original)
+++ hbase/trunk/src/docbkx/configuration.xml Tue Jan 17 05:15:44 2012
@@ -212,35 +212,44 @@ to ensure well-formedness of your docume
xlink:href="http://hadoop.apache.org">Hadoop</link><indexterm>
<primary>Hadoop</primary>
</indexterm></title>
+ <note><title>Please read all of this section</title>
+ <para>Please read this section to the end. Up front we
+ wade through the weeds of Hadoop versions. Later we talk of what you must do in HBase
+ to make it work w/ a particular Hadoop version.</para>
+ </note>
- <note>
- <title>On Hadoop Versions?</title>
+ <para>
+ HBase will lose data unless it is running on an HDFS that has a durable
+ <code>sync</code> implementation. Hadoop 0.20.2, Hadoop 0.20.203.0, and Hadoop 0.20.204.0
+ DO NOT have this attribute.
+ Currently only Hadoop versions 0.20.205.x or any release in excess of this
+ version -- this includes hadoop 1.0.0 -- have a working, durable sync
+ <footnote>
+ <title>On Hadoop Versions</title>
<para>The Cloudera blog post <link xlink:href="http://www.cloudera.com/blog/2012/01/an-update-on-apache-hadoop-1-0/">An update on Apache Hadoop 1.0</link>
by Charles Zedlweski has a nice exposition on how all the Hadoop versions relate.
Its worth checking out if you are having trouble making sense of the
Hadoop version morass.
</para>
- </note>
- <para>
- This version of HBase will only run on <link
- xlink:href="http://hadoop.apache.org/common/releases.html">Hadoop
- 0.20.x</link>. It will not run on hadoop 0.21.x (but may run on 0.22.x/0.23.x).
- HBase will lose data unless it is running on an HDFS that has a durable
- <code>sync</code>. Hadoop 0.20.2, Hadoop 0.20.203.0, and Hadoop 0.20.204.0
- DO NOT have this attribute.
- Currently only Hadoop versions 0.20.205.x or any release in excess of this
- version has a durable sync. You have to explicitly enable it though by
- setting <varname>dfs.support.append</varname> equal to true on both
- the client side -- in <filename>hbase-site.xml</filename> though it should
- be on in your <filename>base-default.xml</filename> file -- and on the
- serverside in <filename>hdfs-site.xml</filename> (You will have to restart
- your cluster after setting this configuration). Ignore the chicken-little
- comment you'll find in the <filename>hdfs-site.xml</filename> in the
- description for this configuration; it says it is not enabled because there
+ </footnote>. Sync has to be explicitly enabled by setting
+ <varname>dfs.support.append</varname> equal
+ to true on both the client side -- in <filename>hbase-site.xml</filename>
+ -- and on the serverside in <filename>hdfs-site.xml</filename> (The sync
+ facility HBase needs is a subset of the append code path).
+ <programlisting>
+ <property>
+ <name>dfs.support.append</name>
+ <value>true</value>
+ </property>
+ </programlisting>
+ You will have to restart your cluster after making this edit. Ignore the chicken-little
+ comment you'll find in the <filename>hdfs-default.xml</filename> in the
+ description for the <varname>dfs.support.append</varname> configuration; it says it is not enabled because there
are <quote>... bugs in the 'append code' and is not supported in any production
- cluster.</quote> because it is not true (I'm sure there are bugs but the
- append code has been running in production at large scale deploys and is on
- by default in the offerings of hadoop by commercial vendors)
+ cluster.</quote>. This comment is stale, from another era, and while I'm sure there
+ are bugs, the sync/append code has been running
+ in production at large scale deploys and is on
+ by default in the offerings of hadoop by commercial vendors
<footnote><para>Until recently only the
<link xlink:href="http://svn.apache.org/viewvc/hadoop/common/branches/branch-0.20-append/">branch-0.20-append</link>
branch had a working sync but no official release was ever made from this branch.