Author: stack
Date: Fri Sep 3 15:20:19 2010
New Revision: 992324
URL: http://svn.apache.org/viewvc?rev=992324&view=rev
Log:
Edit of what is done on WAL exceptions
Modified:
hbase/trunk/src/docbkx/book.xml
Modified: hbase/trunk/src/docbkx/book.xml
URL:
http://svn.apache.org/viewvc/hbase/trunk/src/docbkx/book.xml?rev=992324&r1=992323&r2=992324&view=diff
==============================================================================
--- hbase/trunk/src/docbkx/book.xml (original)
+++ hbase/trunk/src/docbkx/book.xml Fri Sep 3 15:20:19 2010
@@ -7,7 +7,20 @@
xmlns:html="http://www.w3.org/1999/xhtml";
xmlns:db="http://docbook.org/ns/docbook";>
<info>
- <title>HBase Book<?eval ${project.version}?></title>
+ <title>The <link xlink:href="http://www.hbase.org";>HBase</link>
+ Book</title>
+
+ <revhistory>
+ <revision>
+ <date />
+
+ <revdescription>Initial layout</revdescription>
+
+ <revnumber>
+ <?eval ${project.version}?>
+ </revnumber>
+ </revision>
+ </revhistory>
</info>
<chapter xml:id="getting_started">
@@ -595,34 +608,58 @@
<title>The WAL</title>
<subtitle>HBase's<link
- xlink:href="http://en.wikipedia.org/wiki/Write-ahead_logging";> <link
- linkend="???">Write-Ahead Log</link></link></subtitle>
+ xlink:href="http://en.wikipedia.org/wiki/Write-ahead_logging";> Write-Ahead
+ Log</link></subtitle>
<para>Each RegionServer adds updates to its <link linkend="???">WAL</link>
first, and then to memory.</para>
- <para></para>
-
<section>
- <title>How EOFExceptions are treated when splitting a crashed
- RegionServers' WALs </title>
+ <title>What is the purpose of the HBase WAL</title>
- <para>If we get an EOF while splitting logs, we proceed with the split
- even when <varname>hbase.hlog.split.skip.errors</varname> ==
- <constant>false</constant>. An EOF while reading the last log in the set
- of files to split is near-guaranteed since the RegionServer likely
- crashed mid-write of a record. But we'll continue even if we got an EOF
- reading other than the last file in the set.<footnote>
- <para>For background, see <link
-
xlink:href="https://issues.apache.org/jira/browse/HBASE-2643";>HBASE-2643
- Figure how to deal with eof splitting logs</link></para>
- </footnote></para>
+ <para>The HBase WAL is...</para>
</section>
- </chapter>
- <appendix>
- <title></title>
+ <section>
+ <title>WAL splitting</title>
+
+ <subtitle>How edits are recovered from a crashed RegionServer</subtitle>
+
+ <para>When a RegionServer crashes, it will lose its ephemeral lease in
+ ZooKeeper...TODO</para>
+
+ <section>
+ <title><varname>hbase.hlog.split.skip.errors</varname></title>
- <para></para>
- </appendix>
+ <para>When set to <constant>true</constant>, the default, any error
+ encountered splitting will be logged, the problematic WAL will be
+ moved into the <filename>.corrupt</filename> directory under the hbase
+ <varname>rootdir</varname>, and processing will continue. If set to
+ <constant>false</constant>, the exception will be propagated and the
+ split logged as failed.<footnote>
+ <para>See <link
+
xlink:href="https://issues.apache.org/jira/browse/HBASE-2958";>HBASE-2958
+ When hbase.hlog.split.skip.errors is set to false, we fail the
+ split but thats it</link>. We need to do more than just fail split
+ if this flag is set.</para>
+ </footnote></para>
+ </section>
+
+ <section>
+ <title>How EOFExceptions are treated when splitting a crashed
+ RegionServers' WALs</title>
+
+ <para>If we get an EOF while splitting logs, we proceed with the split
+ even when <varname>hbase.hlog.split.skip.errors</varname> ==
+ <constant>false</constant>. An EOF while reading the last log in the
+ set of files to split is near-guaranteed since the RegionServer likely
+ crashed mid-write of a record. But we'll continue even if we got an
+ EOF reading other than the last file in the set.<footnote>
+ <para>For background, see <link
+
xlink:href="https://issues.apache.org/jira/browse/HBASE-2643";>HBASE-2643
+ Figure how to deal with eof splitting logs</link></para>
+ </footnote></para>
+ </section>
+ </section>
+ </chapter>
</book>
