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Subject [08/11] git commit: Merge branch '1.5.1-SNAPSHOT' into 1.6.0-SNAPSHOT
Date Wed, 11 Dec 2013 14:16:23 GMT
Merge branch '1.5.1-SNAPSHOT' into 1.6.0-SNAPSHOT


Branch: refs/heads/master
Commit: 0d874d05a67950d9d5d9bec96de22e71f946b62c
Parents: 8f92585 e9423ae
Author: Eric Newton <>
Authored: Wed Dec 11 09:15:55 2013 -0500
Committer: Eric Newton <>
Committed: Wed Dec 11 09:15:55 2013 -0500

 .../chapters/administration.tex                 | 32 ++++++++++++++++++++
 .../src/main/resources/docs/administration.html | 23 ++++++++++++++
 2 files changed, 55 insertions(+)
diff --cc server/monitor/src/main/resources/docs/administration.html
index 96f4a8b,0000000..51b1c31
mode 100644,000000..100644
--- a/server/monitor/src/main/resources/docs/administration.html
+++ b/server/monitor/src/main/resources/docs/administration.html
@@@ -1,148 -1,0 +1,171 @@@
 +  Licensed to the Apache Software Foundation (ASF) under one or more
 +  contributor license agreements.  See the NOTICE file distributed with
 +  this work for additional information regarding copyright ownership.
 +  The ASF licenses this file to You under the Apache License, Version 2.0
 +  (the "License"); you may not use this file except in compliance with
 +  the License.  You may obtain a copy of the License at
 +  Unless required by applicable law or agreed to in writing, software
 +  distributed under the License is distributed on an "AS IS" BASIS,
 +  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 +  See the License for the specific language governing permissions and
 +  limitations under the License.
 +<title>Accumulo Administration</title>
 +<link rel='stylesheet' type='text/css' href='documentation.css' media='screen'/>
 +<h1>Apache Accumulo Documentation : Administration</h1>
 +<h3>Starting accumulo for the first time</h3>
 +<p>For the most part, accumulo is ready to go out of the box. To start it, first you
must distribute and install
 +the accumulo software to each machine in the cloud that you wish to run on. The software
should be installed
 +in the same directory on each machine and configured identically (or at least similarly...
see the configuration
 +sections for more details). Select one machine to be your bootstrap machine, the one that
you will start accumulo
 +with. Note that you must have passphrase-less ssh access to each machine from your bootstrap
machine. On this machine,
 +create a conf/masters and conf/slaves file. In the masters file, type the hostname of the
machine you wish to run the master on (probably localhost).
 +In the slaves file, type the hostnames, separated by newlines of each machine you wish to
participate in accumulo as a tablet server. If you neglect
 +to create these files, the startup scripts will assume you are trying to run on localhost
only, and will instantiate a single-node instance only.
 +It is probably a good idea to back up these files, or distribute them to the other nodes
as well, so that you can easily boot up accumulo
 +from another machine, if necessary. You can also make create a <code>conf/</code>
file if you want to configure any custom environment variables.
 +<p>Once properly configured, you can initialize or prepare an instance of accumulo
by running: <code>bin/accumulo&nbsp;init</code><br />
 +Follow the prompts and you are ready to go. This step only prepares accumulo to run, it
does not start up accumulo.
 +<h3>Starting accumulo</h3>
 +<p>Once you have configured accumulo to your liking, and distributed the appropriate
configuration to each machine, you can start accumulo with
 +bin/ If at any time, you wish to bring accumulo servers online after one or
more have been shutdown, you can run bin/ again.
 +This step will only start services that are not already running. Be aware that if you run
this command on more than one machine, you may unintentionally
 +start an extra copy of the garbage collector service and the monitoring service, since each
of these will run on the server on which you run this script.
 +<h3>Stopping accumulo</h3>
 +<p>Similar to the script, we provide a bin/ script to shut
down accumulo. This will prompt for the root password so that it can
 +ask the master to shut down the tablet servers gracefully. If the tablet servers do not
respond, or the master takes too long, you can force a shutdown by hitting Ctrl-C
 +at the password prompt, and waiting 15 seconds for the script to force a shutdown. Normally,
once the shutdown happens gracefully, unresponsive tablet servers are
 +forcibly shut down after 5 seconds.
++<h3>Adding a Node</h3>
++<p>Update your <code>$ACCUMULO_HOME/conf/slaves</code> (or <code>$ACCUMULO_CONF_DIR/slaves</code>)
file to account for the addition; at a minimum this needs to be on the host(s) being added,
but in practice it's good to ensure consistent configuration across all nodes.</p>
++$ACCUMULO_HOME/bin/accumulo admin start &gt;host(s)&gt; {&lt;host&gt; ...}
++<p>Alternatively, you can ssh to each of the hosts you want to add and run <code>$ACCUMULO_HOME/bin/</code>.</p>
++<p>Make sure the host in question has the new configuration, or else the tablet server
won't start.</p>
++<h3>Decomissioning a Node</h3>
++<p>If you need to take a node out of operation, you can trigger a graceful shutdown
of a tablet server. Accumulo will automatically rebalance the tablets across the available
tablet servers.</p>
++$ACCUMULO_HOME/bin/accumulo admin stop &gt;host(s)&gt; {&lt;host&gt; ...}
++<p>Alternatively, you can ssh to each of the hosts you want to remove and run <code>$ACCUMULO_HOME/bin/</code>.</p>
++<p>Be sure to update your <code>$ACCUMULO_HOME/conf/slaves</code> (or
<code>$ACCUMULO_CONF_DIR/slaves</code>) file to account for the removal of these
hosts. Bear in mind that the monitor will not re-read the slaves file automatically, so it
will report the decomissioned servers as down; it's recommended that you restart the monitor
so that the node list is up to date.</p>
 +<p>Accumulo configuration information is stored in a xml file and ZooKeeper.  System
 +configuration information is stored in accumulo-site.xml. In order for accumulo to
 +find this file its directory must be on the classpath.  Accumulo will log a warning if it
can not find 
 +it, and will use built-in default values. The accumulo scripts try to put the config directory
on the classpath.  
 +<p>Starting with version 1.0, per-table configuration was
 +introduced. This information is stored in ZooKeeper. This information
 +can be manipulated using the config command in the accumulo
 +shell. ZooKeeper will notify all tablet servers when config properties
 +are modified. This makes it possible to change major compaction
 +settings, for example, for a table while accumulo is running.
 +<p>Per-table configuration settings override system settings. 
 +<p>See the possible configuration options and their default values <a href='config.html'>here</a>
 +<h3>Managing system resources</h3>
 +<p>It is very important how disk and memory usage are allocated across the cluster
and how servers processes are allocated across the cluster. 
 + <li> On larger clusters, run the namenode, secondary namenode, jobtracker, accumulo
master, and zookeepers on dedicated nodes.  On a smaller cluster you may want to run all master
processes on one node.  When doing this ensure that the max total memory that could be used
by all master processes does not exceed system memory.  Swapping on your single master node
would not be good.
 + <li> Accumulo 1.2 and earlier rely on zookeeper but do not use it heavily.  On a
large cluster setting up 3 or 5 zookeepers should be plenty.  Since there is no performance
gain when running more zookeepers, fault tolerance is the only benefit.
 + <li> On slave nodes ensure the memory used by all slave processes is less than system
memory.  For example the following slave node config could use up to 38G of RAM : tablet server
3G, logger 1G, data node 2G, up to 10 mappers each using 2G, and up 6 reducers each using
2G.  If the slave nodes only have 32G, then using 38G will result in swapping which could
cause tablet server to lose their lock in zookeeper and die.  Even if swapping does not cause
tablet servers to die, it will kill performance.
 + <li>Accumulo and map reduce will work with less memory, but it has an impact.  Accumulo
will minor compact more frequently when it has less map memory, resulting in more major compactions.
 The minor and major compactions both use CPU and HDFS I/O.   The same goes for map reduce,
the less memory you give it, the more it has to sort and spill.  Try to minimize spilling
and compactions as much as possible without causing swapping.
 + <li>Accumulo writes data to disk before it sorts it in memory.  This allows data
that was in memory when a tablet server crashes to be recovered.  Each slave node needs a
local directory to write this data to.  Ensure the file system holding this directory has
at least 100G free on all nodes.  Also, if this directory is in a filesystem used by map reduce
or hdfs they may effect each others performance.
 +<p>There are a few settings that determine how much memory accumulo tablet
 +servers use.  In there is a setting called
 +ACCUMULO_TSERVER_OPTS.  By default this is set to something like "-Xmx512m
 +-Xms512m".  These are Java jvm options asking Java to use 512 megabytes of
 +memory.  By default accumulo stores data written to it outside of the Java
 +memory space in order to avoid pauses caused by the Java garbage collector.  The
 +amount of memory it uses for this data is determined by the accumulo setting
 +"tserver.memory.maps.max".  Since this memory is outside of the Java managed
 +memory, the process can grow larger than the -Xmx setting.  So if -Xmx is set
 +to 512M and tserver.memory.maps.max is set to 1G, a tablet server process can
 +be expected to use 1.5G.  If tserver.memory.maps.native.enabled is set to
 +false, then accumulo will only use memory managed by Java and the process will
 +not use more than what -Xmx is set to.  In this case the
 +tserver.memory.maps.max setting should be 75% of the -Xmx setting. 
 +<p>The linux kernel will swap out memory of running programs to increase
 +the size of the disk buffers.  This tendency to swap out is controlled by
 +a kernel setting called "swappiness."  This behavior does not work well for
 +large java servers.  When a java process runs a garbage collection, it touches
 +lots of pages forcing all swapped out pages back into memory.  It is suggested
 +that swappiness be set to zero.
 + # sysctl -w vm.swappiness=0
 + # echo "vm.swappiness = 0" &gt;&gt; /etc/sysctl.conf
 +<h3>Hadoop timeouts</h3>
 +<p>In order to detect failed datanodes, use shorter timeouts.  Add the following to
 +hdfs-site.xml file:
 +  &lt;property&gt;
 +    &lt;name&gt;dfs.socket.timeout&lt;/name&gt;
 +    &lt;value&gt;3000&lt;/value&gt;
 +  &lt;/property&gt;
 +  &lt;property&gt;
 +    &lt;name&gt;dfs.socket.write.timeout&lt;/name&gt;
 +    &lt;value&gt;5000&lt;/value&gt;
 +  &lt;/property&gt;
 +  &lt;property&gt;
 +    &lt;name&gt;ipc.client.connect.timeout&lt;/name&gt;
 +    &lt;value&gt;1000&lt;/value&gt;
 +  &lt;/property&gt;
 +  &lt;property&gt;
 +    &lt;name&gt;ipc.clident.connect.max.retries.on.timeouts&lt;/name&gt;
 +    &lt;value&gt;2&lt;/value&gt;
 +  &lt;/property&gt;

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