Author: dmeil
Date: Mon Feb 13 15:00:51 2012
New Revision: 1243550
URL: http://svn.apache.org/viewvc?rev=1243550&view=rev
Log:
hbase-5390. book.xml - adding section in Arch/Master about what happens if
master dies.
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=1243550&r1=1243549&r2=1243550&view=diff
==============================================================================
--- hbase/trunk/src/docbkx/book.xml (original)
+++ hbase/trunk/src/docbkx/book.xml Mon Feb 13 15:00:51 2012
@@ -1378,6 +1378,9 @@ if (!b) {
the client will requery the catalog tables to determine the new
location of the user region.
</para>
+ <para>See <xref linkend="master.runtime"/> for more information about the
impact of the Master on HBase Client
+ communication.
+ </para>
<para>Administrative functions are handled through <link
xlink:href="http://hbase.apache.org/apidocs/org/apache/hadoop/hbase/client/HBaseAdmin.html";>HBaseAdmin</link>
</para>
<section xml:id="client.connections"><title>Connections</title>
@@ -1661,6 +1664,15 @@ rs.close();
take over the Master role.
</para>
</section>
+ <section xml:id="master.runtime"><title>Runtime Impact</title>
+ <para>A common dist-list question is what happens to an HBase cluster
when the Master goes down. Because the
+ HBase client talks directly to the RegionServers, the cluster can
still function in a "steady
+ state." Additionally, per <xref linkend="arch.catalog"/> ROOT and
META exist as HBase tables (i.e., are
+ not resident in the Master). However, the Master controls critical
functions such as RegionServer failover and
+ completing region splits. So while the cluster can still run
<emphasis>for a time</emphasis> without the Master,
+ the Master should be restarted as soon as possible.
+ </para>
+ </section>
<section xml:id="master.api"><title>Interface</title>
<para>The methods exposed by <code>HMasterInterface</code> are
primarily metadata-oriented methods:
<itemizedlist>
