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HADOOP-6738. Move cluster_setup.xml, hod_scheduler, commands_manual from MapReduce to Common. 

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@951480 13f79535-47bb-0310-9956-ffa450edef68
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Thomas White 2010-06-04 16:34:18 +00:00
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@ -932,6 +932,9 @@ Release 0.21.0 - Unreleased
HADOOP-6585. Add FileStatus#isDirectory and isFile. (Eli Collins via
tomwhite)
HADOOP-6738. Move cluster_setup.xml from MapReduce to Common.
(Tom White via tomwhite)
OPTIMIZATIONS
HADOOP-5595. NameNode does not need to run a replicator to choose a

536
src/docs/src/documentation/content/xdocs/cluster_setup.xml
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@ -33,20 +33,20 @@
Hadoop clusters ranging from a few nodes to extremely large clusters with
thousands of nodes.</p>
<p>
To play with Hadoop, you may first want to install Hadoop on a single machine (see <a href="single_node_setup.html"> Single Node Setup</a>).
To play with Hadoop, you may first want to install Hadoop on a single machine (see <a href="single_node_setup.html"> Hadoop Quick Start</a>).
</p>
</section>
<section>
<title>Prerequisites</title>
<title>Pre-requisites</title>
<ol>
<li>
Make sure all <a href="single_node_setup.html#PreReqs">required software</a>
Make sure all <a href="single_node_setup.html#PreReqs">requisite</a> software
is installed on all nodes in your cluster.
</li>
<li>
<a href="single_node_setup.html#Download">Download</a> the Hadoop software.
<a href="single_node_setup.html#Download">Get</a> the Hadoop software.
</li>
</ol>
</section>
@ -81,21 +81,23 @@
<ol>
<li>
Read-only default configuration -
<a href="ext:common-default">src/common/common-default.xml</a>,
<a href="ext:hdfs-default">src/hdfs/hdfs-default.xml</a> and
<a href="ext:mapred-default">src/mapred/mapred-default.xml</a>.
<a href="ext:common-default">src/core/core-default.xml</a>,
<a href="ext:hdfs-default">src/hdfs/hdfs-default.xml</a>,
<a href="ext:mapred-default">src/mapred/mapred-default.xml</a> and
<a href="ext:mapred-queues">conf/mapred-queues.xml.template</a>.
</li>
<li>
Site-specific configuration -
<em>conf/core-site.xml</em>,
<em>conf/hdfs-site.xml</em> and
<em>conf/mapred-site.xml</em>.
<a href="#core-site.xml">conf/core-site.xml</a>,
<a href="#hdfs-site.xml">conf/hdfs-site.xml</a>,
<a href="#mapred-site.xml">conf/mapred-site.xml</a> and
<a href="#mapred-queues.xml">conf/mapred-queues.xml</a>.
</li>
</ol>
<p>To learn more about how the Hadoop framework is controlled by these
configuration files see
<a href="ext:api/org/apache/hadoop/conf/configuration">Class Configuration</a>.</p>
configuration files, look
<a href="ext:api/org/apache/hadoop/conf/configuration">here</a>.</p>
<p>Additionally, you can control the Hadoop scripts found in the
<code>bin/</code> directory of the distribution, by setting site-specific
@ -163,9 +165,8 @@
<title>Configuring the Hadoop Daemons</title>
<p>This section deals with important parameters to be specified in the
following:
<br/>
<code>conf/core-site.xml</code>:</p>
following:</p>
<anchor id="core-site.xml"/><p><code>conf/core-site.xml</code>:</p>
<table>
<tr>
@ -180,7 +181,7 @@
</tr>
</table>
<p><br/><code>conf/hdfs-site.xml</code>:</p>
<anchor id="hdfs-site.xml"/><p><code>conf/hdfs-site.xml</code>:</p>
<table>
<tr>
@ -212,7 +213,7 @@
</tr>
</table>
<p><br/><code>conf/mapred-site.xml</code>:</p>
<anchor id="mapred-site.xml"/><p><code>conf/mapred-site.xml</code>:</p>
<table>
<tr>
@ -221,12 +222,12 @@
<th>Notes</th>
</tr>
<tr>
<td>mapred.job.tracker</td>
<td>mapreduce.jobtracker.address</td>
<td>Host or IP and port of <code>JobTracker</code>.</td>
<td><em>host:port</em> pair.</td>
</tr>
<tr>
<td>mapred.system.dir</td>
<td>mapreduce.jobtracker.system.dir</td>
<td>
Path on the HDFS where where the Map/Reduce framework stores
system files e.g. <code>/hadoop/mapred/system/</code>.
@ -237,7 +238,7 @@
</td>
</tr>
<tr>
<td>mapred.local.dir</td>
<td>mapreduce.cluster.local.dir</td>
<td>
Comma-separated list of paths on the local filesystem where
temporary Map/Reduce data is written.
@ -264,7 +265,7 @@
</td>
</tr>
<tr>
<td>mapred.hosts/mapred.hosts.exclude</td>
<td>mapreduce.jobtracker.hosts.filename/mapreduce.jobtracker.hosts.exclude.filename</td>
<td>List of permitted/excluded TaskTrackers.</td>
<td>
If necessary, use these files to control the list of allowable
@ -272,82 +273,331 @@
</td>
</tr>
<tr>
<td>mapred.queue.names</td>
<td>Comma separated list of queues to which jobs can be submitted.</td>
<td>mapreduce.cluster.job-authorization-enabled</td>
<td>Boolean, specifying whether job ACLs are supported for
authorizing view and modification of a job</td>
<td>
The Map/Reduce system always supports atleast one queue
with the name as <em>default</em>. Hence, this parameter's
value should always contain the string <em>default</em>.
Some job schedulers supported in Hadoop, like the
<a href="http://hadoop.apache.org/mapreduce/docs/current/capacity_scheduler.html">Capacity Scheduler</a>,
support multiple queues. If such a scheduler is
being used, the list of configured queue names must be
specified here. Once queues are defined, users can submit
jobs to a queue using the property name
<em>mapred.job.queue.name</em> in the job configuration.
There could be a separate
configuration file for configuring properties of these
queues that is managed by the scheduler.
Refer to the documentation of the scheduler for information on
the same.
If <em>true</em>, job ACLs would be checked while viewing or
modifying a job. More details are available at
<a href ="ext:mapred-tutorial/JobAuthorization">Job Authorization</a>.
</td>
</tr>
<tr>
<td>mapred.acls.enabled</td>
<td>Specifies whether ACLs are supported for controlling job
submission and administration</td>
<td>
If <em>true</em>, ACLs would be checked while submitting
and administering jobs. ACLs can be specified using the
configuration parameters of the form
<em>mapred.queue.queue-name.acl-name</em>, defined below.
</td>
</tr>
</table>
<p><br/><code> conf/mapred-queue-acls.xml</code></p>
<table>
<tr>
<th>Parameter</th>
<th>Value</th>
<th>Notes</th>
</tr>
<tr>
<td>mapred.queue.<em>queue-name</em>.acl-submit-job</td>
<td>List of users and groups that can submit jobs to the
specified <em>queue-name</em>.</td>
<td>
The list of users and groups are both comma separated
list of names. The two lists are separated by a blank.
Example: <em>user1,user2 group1,group2</em>.
If you wish to define only a list of groups, provide
a blank at the beginning of the value.
</td>
</tr>
<tr>
<td>mapred.queue.<em>queue-name</em>.acl-administer-job</td>
<td>List of users and groups that can change the priority
or kill jobs that have been submitted to the
specified <em>queue-name</em>.</td>
<td>
The list of users and groups are both comma separated
list of names. The two lists are separated by a blank.
Example: <em>user1,user2 group1,group2</em>.
If you wish to define only a list of groups, provide
a blank at the beginning of the value. Note that an
owner of a job can always change the priority or kill
his/her own job, irrespective of the ACLs.
</td>
</tr>
</table>
</table>
<p>Typically all the above parameters are marked as
<a href="ext:api/org/apache/hadoop/conf/configuration/final_parameters">
final</a> to ensure that they cannot be overriden by user-applications.
</p>
<anchor id="mapred-queues.xml"/><p><code>conf/mapred-queues.xml
</code>:</p>
<p>This file is used to configure the queues in the Map/Reduce
system. Queues are abstract entities in the JobTracker that can be
used to manage collections of jobs. They provide a way for
administrators to organize jobs in specific ways and to enforce
certain policies on such collections, thus providing varying
levels of administrative control and management functions on jobs.
</p>
<p>One can imagine the following sample scenarios:</p>
<ul>
<li> Jobs submitted by a particular group of users can all be
submitted to one queue. </li>
<li> Long running jobs in an organization can be submitted to a
queue. </li>
<li> Short running jobs can be submitted to a queue and the number
of jobs that can run concurrently can be restricted. </li>
</ul>
<p>The usage of queues is closely tied to the scheduler configured
at the JobTracker via <em>mapreduce.jobtracker.taskscheduler</em>.
The degree of support of queues depends on the scheduler used. Some
schedulers support a single queue, while others support more complex
configurations. Schedulers also implement the policies that apply
to jobs in a queue. Some schedulers, such as the Fairshare scheduler,
implement their own mechanisms for collections of jobs and do not rely
on queues provided by the framework. The administrators are
encouraged to refer to the documentation of the scheduler they are
interested in for determining the level of support for queues.</p>
<p>The Map/Reduce framework supports some basic operations on queues
such as job submission to a specific queue, access control for queues,
queue states, viewing configured queues and their properties
and refresh of queue properties. In order to fully implement some of
these operations, the framework takes the help of the configured
scheduler.</p>
<p>The following types of queue configurations are possible:</p>
<ul>
<li> Single queue: The default configuration in Map/Reduce comprises
of a single queue, as supported by the default scheduler. All jobs
are submitted to this default queue which maintains jobs in a priority
based FIFO order.</li>
<li> Multiple single level queues: Multiple queues are defined, and
jobs can be submitted to any of these queues. Different policies
can be applied to these queues by schedulers that support this
configuration to provide a better level of support. For example,
the <a href="ext:capacity-scheduler">capacity scheduler</a>
provides ways of configuring different
capacity and fairness guarantees on these queues.</li>
<li> Hierarchical queues: Hierarchical queues are a configuration in
which queues can contain other queues within them recursively. The
queues that contain other queues are referred to as
container queues. Queues that do not contain other queues are
referred as leaf or job queues. Jobs can only be submitted to leaf
queues. Hierarchical queues can potentially offer a higher level
of control to administrators, as schedulers can now build a
hierarchy of policies where policies applicable to a container
queue can provide context for policies applicable to queues it
contains. It also opens up possibilities for delegating queue
administration where administration of queues in a container queue
can be turned over to a different set of administrators, within
the context provided by the container queue. For example, the
<a href="ext:capacity-scheduler">capacity scheduler</a>
uses hierarchical queues to partition capacity of a cluster
among container queues, and allowing queues they contain to divide
that capacity in more ways.</li>
</ul>
<p>Most of the configuration of the queues can be refreshed/reloaded
without restarting the Map/Reduce sub-system by editing this
configuration file as described in the section on
<a href="commands_manual.html#RefreshQueues">reloading queue
configuration</a>.
Not all configuration properties can be reloaded of course,
as will description of each property below explain.</p>
<p>The format of conf/mapred-queues.xml is different from the other
configuration files, supporting nested configuration
elements to support hierarchical queues. The format is as follows:
</p>
<source>
&lt;queues aclsEnabled="$aclsEnabled"&gt;
&lt;queue&gt;
&lt;name&gt;$queue-name&lt;/name&gt;
&lt;state&gt;$state&lt;/state&gt;
&lt;queue&gt;
&lt;name&gt;$child-queue1&lt;/name&gt;
&lt;properties&gt;
&lt;property key="$key" value="$value"/&gt;
...
&lt;/properties&gt;
&lt;queue&gt;
&lt;name&gt;$grand-child-queue1&lt;/name&gt;
...
&lt;/queue&gt;
&lt;/queue&gt;
&lt;queue&gt;
&lt;name&gt;$child-queue2&lt;/name&gt;
...
&lt;/queue&gt;
...
...
...
&lt;queue&gt;
&lt;name&gt;$leaf-queue&lt;/name&gt;
&lt;acl-submit-job&gt;$acls&lt;/acl-submit-job&gt;
&lt;acl-administer-jobs&gt;$acls&lt;/acl-administer-jobs&gt;
&lt;properties&gt;
&lt;property key="$key" value="$value"/&gt;
...
&lt;/properties&gt;
&lt;/queue&gt;
&lt;/queue&gt;
&lt;/queues&gt;
</source>
<table>
<tr>
<th>Tag/Attribute</th>
<th>Value</th>
<th>
<a href="commands_manual.html#RefreshQueues">Refresh-able?</a>
</th>
<th>Notes</th>
</tr>
<tr>
<td><anchor id="queues_tag"/>queues</td>
<td>Root element of the configuration file.</td>
<td>Not-applicable</td>
<td>All the queues are nested inside this root element of the
file. There can be only one root queues element in the file.</td>
</tr>
<tr>
<td>aclsEnabled</td>
<td>Boolean attribute to the
<a href="#queues_tag"><em>&lt;queues&gt;</em></a> tag
specifying whether ACLs are supported for controlling job
submission and administration for <em>all</em> the queues
configured.
</td>
<td>Yes</td>
<td>If <em>false</em>, ACLs are ignored for <em>all</em> the
configured queues. <br/><br/>
If <em>true</em>, the user and group details of the user
are checked against the configured ACLs of the corresponding
job-queue while submitting and administering jobs. ACLs can be
specified for each queue using the queue-specific tags
"acl-$acl_name", defined below. ACLs are checked only against
the job-queues, i.e. the leaf-level queues; ACLs configured
for the rest of the queues in the hierarchy are ignored.
</td>
</tr>
<tr>
<td><anchor id="queue_tag"/>queue</td>
<td>A child element of the
<a href="#queues_tag"><em>&lt;queues&gt;</em></a> tag or another
<a href="#queue_tag"><em>&lt;queue&gt;</em></a>. Denotes a queue
in the system.
</td>
<td>Not applicable</td>
<td>Queues can be hierarchical and so this element can contain
children of this same type.</td>
</tr>
<tr>
<td>name</td>
<td>Child element of a
<a href="#queue_tag"><em>&lt;queue&gt;</em></a> specifying the
name of the queue.</td>
<td>No</td>
<td>Name of the queue cannot contain the character <em>":"</em>
which is reserved as the queue-name delimiter when addressing a
queue in a hierarchy.</td>
</tr>
<tr>
<td>state</td>
<td>Child element of a
<a href="#queue_tag"><em>&lt;queue&gt;</em></a> specifying the
state of the queue.
</td>
<td>Yes</td>
<td>Each queue has a corresponding state. A queue in
<em>'running'</em> state can accept new jobs, while a queue in
<em>'stopped'</em> state will stop accepting any new jobs. State
is defined and respected by the framework only for the
leaf-level queues and is ignored for all other queues.
<br/><br/>
The state of the queue can be viewed from the command line using
<code>'bin/mapred queue'</code> command and also on the the Web
UI.<br/><br/>
Administrators can stop and start queues at runtime using the
feature of <a href="commands_manual.html#RefreshQueues">reloading
queue configuration</a>. If a queue is stopped at runtime, it
will complete all the existing running jobs and will stop
accepting any new jobs.
</td>
</tr>
<tr>
<td>acl-submit-job</td>
<td>Child element of a
<a href="#queue_tag"><em>&lt;queue&gt;</em></a> specifying the
list of users and groups that can submit jobs to the specified
queue.</td>
<td>Yes</td>
<td>
Applicable only to leaf-queues.<br/><br/>
The list of users and groups are both comma separated
list of names. The two lists are separated by a blank.
Example: <em>user1,user2 group1,group2</em>.
If you wish to define only a list of groups, provide
a blank at the beginning of the value.
<br/><br/>
</td>
</tr>
<tr>
<td>acl-administer-job</td>
<td>Child element of a
<a href="#queue_tag"><em>&lt;queue&gt;</em></a> specifying the
list of users and groups that can change the priority of a job
or kill a job that has been submitted to the specified queue.
</td>
<td>Yes</td>
<td>
Applicable only to leaf-queues.<br/><br/>
The list of users and groups are both comma separated
list of names. The two lists are separated by a blank.
Example: <em>user1,user2 group1,group2</em>.
If you wish to define only a list of groups, provide
a blank at the beginning of the value. Note that an
owner of a job can always change the priority or kill
his/her own job, irrespective of the ACLs.
</td>
</tr>
<tr>
<td><anchor id="properties_tag"/>properties</td>
<td>Child element of a
<a href="#queue_tag"><em>&lt;queue&gt;</em></a> specifying the
scheduler specific properties.</td>
<td>Not applicable</td>
<td>The scheduler specific properties are the children of this
element specified as a group of &lt;property&gt; tags described
below. The JobTracker completely ignores these properties. These
can be used as per-queue properties needed by the scheduler
being configured. Please look at the scheduler specific
documentation as to how these properties are used by that
particular scheduler.
</td>
</tr>
<tr>
<td><anchor id="property_tag"/>property</td>
<td>Child element of
<a href="#properties_tag"><em>&lt;properties&gt;</em></a> for a
specific queue.</td>
<td>Not applicable</td>
<td>A single scheduler specific queue-property. Ignored by
the JobTracker and used by the scheduler that is configured.</td>
</tr>
<tr>
<td>key</td>
<td>Attribute of a
<a href="#property_tag"><em>&lt;property&gt;</em></a> for a
specific queue.</td>
<td>Scheduler-specific</td>
<td>The name of a single scheduler specific queue-property.</td>
</tr>
<tr>
<td>value</td>
<td>Attribute of a
<a href="#property_tag"><em>&lt;property&gt;</em></a> for a
specific queue.</td>
<td>Scheduler-specific</td>
<td>The value of a single scheduler specific queue-property.
The value can be anything that is left for the proper
interpretation by the scheduler that is configured.</td>
</tr>
</table>
<p>Once the queues are configured properly and the Map/Reduce
system is up and running, from the command line one can
<a href="commands_manual.html#QueuesList">get the list
of queues</a> and
<a href="commands_manual.html#QueuesInfo">obtain
information specific to each queue</a>. This information is also
available from the web UI. On the web UI, queue information can be
seen by going to queueinfo.jsp, linked to from the queues table-cell
in the cluster-summary table. The queueinfo.jsp prints the hierarchy
of queues as well as the specific information for each queue.
</p>
<p> Users can submit jobs only to a
leaf-level queue by specifying the fully-qualified queue-name for
the property name <em>mapreduce.job.queuename</em> in the job
configuration. The character ':' is the queue-name delimiter and so,
for e.g., if one wants to submit to a configured job-queue 'Queue-C'
which is one of the sub-queues of 'Queue-B' which in-turn is a
sub-queue of 'Queue-A', then the job configuration should contain
property <em>mapreduce.job.queuename</em> set to the <em>
&lt;value&gt;Queue-A:Queue-B:Queue-C&lt;/value&gt;</em></p>
</section>
<section>
<title>Real-World Cluster Configurations</title>
@ -383,7 +633,7 @@
</tr>
<tr>
<td>conf/mapred-site.xml</td>
<td>mapred.reduce.parallel.copies</td>
<td>mapreduce.reduce.shuffle.parallelcopies</td>
<td>20</td>
<td>
Higher number of parallel copies run by reduces to fetch
@ -392,7 +642,7 @@
</tr>
<tr>
<td>conf/mapred-site.xml</td>
<td>mapred.map.child.java.opts</td>
<td>mapreduce.map.java.opts</td>
<td>-Xmx512M</td>
<td>
Larger heap-size for child jvms of maps.
@ -400,7 +650,7 @@
</tr>
<tr>
<td>conf/mapred-site.xml</td>
<td>mapred.reduce.child.java.opts</td>
<td>mapreduce.reduce.java.opts</td>
<td>-Xmx512M</td>
<td>
Larger heap-size for child jvms of reduces.
@ -417,13 +667,13 @@
</tr>
<tr>
<td>conf/core-site.xml</td>
<td>io.sort.factor</td>
<td>mapreduce.task.io.sort.factor</td>
<td>100</td>
<td>More streams merged at once while sorting files.</td>
</tr>
<tr>
<td>conf/core-site.xml</td>
<td>io.sort.mb</td>
<td>mapreduce.task.io.sort.mb</td>
<td>200</td>
<td>Higher memory-limit while sorting data.</td>
</tr>
@ -448,7 +698,7 @@
</tr>
<tr>
<td>conf/mapred-site.xml</td>
<td>mapred.job.tracker.handler.count</td>
<td>mapreduce.jobtracker.handler.count</td>
<td>60</td>
<td>
More JobTracker server threads to handle RPCs from large
@ -457,13 +707,13 @@
</tr>
<tr>
<td>conf/mapred-site.xml</td>
<td>mapred.reduce.parallel.copies</td>
<td>mapreduce.reduce.shuffle.parallelcopies</td>
<td>50</td>
<td></td>
</tr>
<tr>
<td>conf/mapred-site.xml</td>
<td>tasktracker.http.threads</td>
<td>mapreduce.tasktracker.http.threads</td>
<td>50</td>
<td>
More worker threads for the TaskTracker's http server. The
@ -473,7 +723,7 @@
</tr>
<tr>
<td>conf/mapred-site.xml</td>
<td>mapred.map.child.java.opts</td>
<td>mapreduce.map.java.opts</td>
<td>-Xmx512M</td>
<td>
Larger heap-size for child jvms of maps.
@ -481,7 +731,7 @@
</tr>
<tr>
<td>conf/mapred-site.xml</td>
<td>mapred.reduce.child.java.opts</td>
<td>mapreduce.reduce.java.opts</td>
<td>-Xmx1024M</td>
<td>Larger heap-size for child jvms of reduces.</td>
</tr>
@ -500,11 +750,11 @@
or equal to the -Xmx passed to JavaVM, else the VM might not start.
</p>
<p>Note: <code>mapred.child.java.opts</code> are used only for
<p>Note: <code>mapred.{map|reduce}.child.java.opts</code> are used only for
configuring the launched child tasks from task tracker. Configuring
the memory options for daemons is documented under
the memory options for daemons is documented in
<a href="cluster_setup.html#Configuring+the+Environment+of+the+Hadoop+Daemons">
Configuring the Environment of the Hadoop Daemons</a>.</p>
cluster_setup.html </a></p>
<p>The memory available to some parts of the framework is also
configurable. In map and reduce tasks, performance may be influenced
@ -558,7 +808,7 @@
<table>
<tr><th>Name</th><th>Type</th><th>Description</th></tr>
<tr><td>mapred.tasktracker.taskmemorymanager.monitoring-interval</td>
<tr><td>mapreduce.tasktracker.taskmemorymanager.monitoringinterval</td>
<td>long</td>
<td>The time interval, in milliseconds, between which the TT
checks for any memory violation. The default value is 5000 msec
@ -668,10 +918,11 @@
the tasks. For maximum security, this task controller
sets up restricted permissions and user/group ownership of
local files and directories used by the tasks such as the
job jar files, intermediate files and task log files. Currently
permissions on distributed cache files are opened up to be
accessible by all users. In future, it is expected that stricter
file permissions are set for these files too.
job jar files, intermediate files, task log files and distributed
cache files. Particularly note that, because of this, except the
job owner and tasktracker, no other user can access any of the
local files/directories including those localized as part of the
distributed cache.
</td>
</tr>
</table>
@ -684,7 +935,7 @@
<th>Property</th><th>Value</th><th>Notes</th>
</tr>
<tr>
<td>mapred.task.tracker.task-controller</td>
<td>mapreduce.tasktracker.taskcontroller</td>
<td>Fully qualified class name of the task controller class</td>
<td>Currently there are two implementations of task controller
in the Hadoop system, DefaultTaskController and LinuxTaskController.
@ -715,21 +966,35 @@
<p>
The executable must have specific permissions as follows. The
executable should have <em>6050 or --Sr-s---</em> permissions
user-owned by root(super-user) and group-owned by a group
of which only the TaskTracker's user is the sole group member.
user-owned by root(super-user) and group-owned by a special group
of which the TaskTracker's user is the group member and no job
submitter is. If any job submitter belongs to this special group,
security will be compromised. This special group name should be
specified for the configuration property
<em>"mapreduce.tasktracker.group"</em> in both mapred-site.xml and
<a href="#task-controller.cfg">task-controller.cfg</a>.
For example, let's say that the TaskTracker is run as user
<em>mapred</em> who is part of the groups <em>users</em> and
<em>mapredGroup</em> any of them being the primary group.
<em>specialGroup</em> any of them being the primary group.
Let also be that <em>users</em> has both <em>mapred</em> and
another user <em>X</em> as its members, while <em>mapredGroup</em>
has only <em>mapred</em> as its member. Going by the above
another user (job submitter) <em>X</em> as its members, and X does
not belong to <em>specialGroup</em>. Going by the above
description, the setuid/setgid executable should be set
<em>6050 or --Sr-s---</em> with user-owner as <em>mapred</em> and
group-owner as <em>mapredGroup</em> which has
only <em>mapred</em> as its member(and not <em>users</em> which has
group-owner as <em>specialGroup</em> which has
<em>mapred</em> as its member(and not <em>users</em> which has
<em>X</em> also as its member besides <em>mapred</em>).
</p>
<p>
The LinuxTaskController requires that paths including and leading up
to the directories specified in
<em>mapreduce.cluster.local.dir</em> and <em>hadoop.log.dir</em> to
be set 755 permissions.
</p>
<section>
<title>task-controller.cfg</title>
<p>The executable requires a configuration file called
<em>taskcontroller.cfg</em> to be
present in the configuration directory passed to the ant target
@ -747,8 +1012,8 @@
</p>
<table><tr><th>Name</th><th>Description</th></tr>
<tr>
<td>mapred.local.dir</td>
<td>Path to mapred local directories. Should be same as the value
<td>mapreduce.cluster.local.dir</td>
<td>Path to mapreduce.cluster.local.directories. Should be same as the value
which was provided to key in mapred-site.xml. This is required to
validate paths passed to the setuid executable in order to prevent
arbitrary paths being passed to it.</td>
@ -760,14 +1025,16 @@
permissions on the log files so that they can be written to by the user's
tasks and read by the TaskTracker for serving on the web UI.</td>
</tr>
<tr>
<td>mapreduce.tasktracker.group</td>
<td>Group to which the TaskTracker belongs. The group owner of the
taskcontroller binary should be this group. Should be same as
the value with which the TaskTracker is configured. This
configuration is required for validating the secure access of the
task-controller binary.</td>
</tr>
</table>
<p>
The LinuxTaskController requires that paths including and leading up to
the directories specified in
<em>mapred.local.dir</em> and <em>hadoop.log.dir</em> to be set 755
permissions.
</p>
</section>
</section>
</section>
@ -800,7 +1067,7 @@
monitoring script in <em>mapred-site.xml</em>.</p>
<table>
<tr><th>Name</th><th>Description</th></tr>
<tr><td><code>mapred.healthChecker.script.path</code></td>
<tr><td><code>mapreduce.tasktracker.healthchecker.script.path</code></td>
<td>Absolute path to the script which is periodically run by the
TaskTracker to determine if the node is
healthy or not. The file should be executable by the TaskTracker.
@ -809,18 +1076,18 @@
is not started.</td>
</tr>
<tr>
<td><code>mapred.healthChecker.interval</code></td>
<td><code>mapreduce.tasktracker.healthchecker.interval</code></td>
<td>Frequency at which the node health script is run,
in milliseconds</td>
</tr>
<tr>
<td><code>mapred.healthChecker.script.timeout</code></td>
<td><code>mapreduce.tasktracker.healthchecker.script.timeout</code></td>
<td>Time after which the node health script will be killed by
the TaskTracker if unresponsive.
The node is marked unhealthy. if node health script times out.</td>
</tr>
<tr>
<td><code>mapred.healthChecker.script.args</code></td>
<td><code>mapreduce.tasktracker.healthchecker.script.args</code></td>
<td>Extra arguments that can be passed to the node health script
when launched.
These should be comma separated list of arguments. </td>
@ -857,17 +1124,17 @@
<title>History Logging</title>
<p> The job history files are stored in central location
<code> hadoop.job.history.location </code> which can be on DFS also,
<code> mapreduce.jobtracker.jobhistory.location </code> which can be on DFS also,
whose default value is <code>${HADOOP_LOG_DIR}/history</code>.
The history web UI is accessible from job tracker web UI.</p>
<p> The history files are also logged to user specified directory
<code>hadoop.job.history.user.location</code>
<code>mapreduce.job.userhistorylocation</code>
which defaults to job output directory. The files are stored in
"_logs/history/" in the specified directory. Hence, by default
they will be in "mapred.output.dir/_logs/history/". User can stop
they will be in "mapreduce.output.fileoutputformat.outputdir/_logs/history/". User can stop
logging by giving the value <code>none</code> for
<code>hadoop.job.history.user.location</code> </p>
<code>mapreduce.job.userhistorylocation</code> </p>
<p> User can view the history logs summary in specified directory
using the following command <br/>
@ -880,7 +1147,6 @@
<code>$ bin/hadoop job -history all output-dir</code><br/></p>
</section>
</section>
</section>
<p>Once all the necessary configuration is complete, distribute the files
to the <code>HADOOP_CONF_DIR</code> directory on all the machines,
@ -891,9 +1157,9 @@
<section>
<title>Map/Reduce</title>
<p>The job tracker restart can recover running jobs if
<code>mapred.jobtracker.restart.recover</code> is set true and
<code>mapreduce.jobtracker.restart.recover</code> is set true and
<a href="#Logging">JobHistory logging</a> is enabled. Also
<code>mapred.jobtracker.job.history.block.size</code> value should be
<code>mapreduce.jobtracker.jobhistory.block.size</code> value should be
set to an optimal value to dump job history to disk as soon as
possible, the typical value is 3145728(3MB).</p>
</section>
@ -951,7 +1217,7 @@
and starts the <code>TaskTracker</code> daemon on all the listed slaves.
</p>
</section>
<section>
<title>Hadoop Shutdown</title>

772
src/docs/src/documentation/content/xdocs/commands_manual.xml Normal file
View File

@ -0,0 +1,772 @@
<?xml version="1.0"?>
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<!DOCTYPE document PUBLIC "-//APACHE//DTD Documentation V2.0//EN" "http://forrest.apache.org/dtd/document-v20.dtd">
<document>
<header>
<title>Hadoop Commands Guide</title>
</header>
<body>
<section>
<title>Overview</title>
<p>
All Hadoop commands are invoked by the bin/hadoop script. Running the Hadoop
script without any arguments prints the description for all commands.
</p>
<p>
<code>Usage: hadoop [--config confdir] [COMMAND] [GENERIC_OPTIONS] [COMMAND_OPTIONS]</code>
</p>
<p>
Hadoop has an option parsing framework that employs parsing generic options as well as running classes.
</p>
<table>
<tr><th> COMMAND_OPTION </th><th> Description </th></tr>
<tr>
<td><code>--config confdir</code></td>
<td>Overwrites the default Configuration directory. Default is ${HADOOP_HOME}/conf.</td>
</tr>
<tr>
<td><code>GENERIC_OPTIONS</code></td>
<td>The common set of options supported by multiple commands.</td>
</tr>
<tr>
<td><code>COMMAND</code><br/><code>COMMAND_OPTIONS</code></td>
<td>Various commands with their options are described in the following sections. The commands
have been grouped into <a href="commands_manual.html#User+Commands">User Commands</a>
and <a href="commands_manual.html#Administration+Commands">Administration Commands</a>.</td>
</tr>
</table>
<section>
<title>Generic Options</title>
<p>
The following options are supported by <a href="commands_manual.html#dfsadmin">dfsadmin</a>,
<a href="commands_manual.html#fs">fs</a>, <a href="commands_manual.html#fsck">fsck</a> and
<a href="commands_manual.html#job">job</a>.
Applications should implement
<a href="ext:api/org/apache/hadoop/util/tool">Tool</a> to support
<a href="ext:api/org/apache/hadoop/util/genericoptionsparser">
GenericOptions</a>.
</p>
<table>
<tr><th> GENERIC_OPTION </th><th> Description </th></tr>
<tr>
<td><code>-conf &lt;configuration file&gt;</code></td>
<td>Specify an application configuration file.</td>
</tr>
<tr>
<td><code>-D &lt;property=value&gt;</code></td>
<td>Use value for given property.</td>
</tr>
<tr>
<td><code>-fs &lt;local|namenode:port&gt;</code></td>
<td>Specify a namenode.</td>
</tr>
<tr>
<td><code>-jt &lt;local|jobtracker:port&gt;</code></td>
<td>Specify a job tracker. Applies only to <a href="commands_manual.html#job">job</a>.</td>
</tr>
<tr>
<td><code>-files &lt;comma separated list of files&gt;</code></td>
<td>Specify comma separated files to be copied to the map reduce cluster.
Applies only to <a href="commands_manual.html#job">job</a>.</td>
</tr>
<tr>
<td><code>-libjars &lt;comma seperated list of jars&gt;</code></td>
<td>Specify comma separated jar files to include in the classpath.
Applies only to <a href="commands_manual.html#job">job</a>.</td>
</tr>
<tr>
<td><code>-archives &lt;comma separated list of archives&gt;</code></td>
<td>Specify comma separated archives to be unarchived on the compute machines.
Applies only to <a href="commands_manual.html#job">job</a>.</td>
</tr>
</table>
</section>
</section>
<section>
<title> User Commands </title>
<p>Commands useful for users of a Hadoop cluster.</p>
<section>
<title> archive </title>
<p>
Creates a Hadoop archive. More information see the <a href="ext:hadoop-archives">Hadoop Archives Guide</a>.
</p>
<p>
<code>Usage: hadoop archive -archiveName NAME &lt;src&gt;* &lt;dest&gt;</code>
</p>
<table>
<tr><th> COMMAND_OPTION </th><th> Description </th></tr>
<tr>
<td><code>-archiveName NAME</code></td>
<td>Name of the archive to be created.</td>
</tr>
<tr>
<td><code>src</code></td>
<td>Filesystem pathnames which work as usual with regular expressions.</td>
</tr>
<tr>
<td><code>dest</code></td>
<td>Destination directory which would contain the archive.</td>
</tr>
</table>
</section>
<section>
<title> distcp </title>
<p>
Copy file or directories recursively. More information can be found at <a href="ext:distcp">DistCp Guide</a>.
</p>
<p>
<code>Usage: hadoop distcp &lt;srcurl&gt; &lt;desturl&gt;</code>
</p>
<table>
<tr><th> COMMAND_OPTION </th><th> Description </th></tr>
<tr>
<td><code>srcurl</code></td>
<td>Source Url</td>
</tr>
<tr>
<td><code>desturl</code></td>
<td>Destination Url</td>
</tr>
</table>
</section>
<section>
<title> fs </title>
<p>
Runs a generic filesystem user client.
</p>
<p>
<code>Usage: hadoop fs [</code><a href="commands_manual.html#Generic+Options">GENERIC_OPTIONS</a><code>]
[COMMAND_OPTIONS]</code>
</p>
<p>
The various COMMAND_OPTIONS can be found at
<a href="file_system_shell.html">File System Shell Guide</a>.
</p>
</section>
<section>
<title> fsck </title>
<p>
Runs a HDFS filesystem checking utility. See <a href="http://hadoop.apache.org/hdfs/docs/current/hdfs_user_guide.html#Fsck">Fsck</a> for more info.
</p>
<p><code>Usage: hadoop fsck [</code><a href="commands_manual.html#Generic+Options">GENERIC_OPTIONS</a><code>]
&lt;path&gt; [-move | -delete | -openforwrite] [-files [-blocks
[-locations | -racks]]]</code></p>
<table>
<tr><th> COMMAND_OPTION </th><th> Description </th></tr>
<tr>
<td><code>&lt;path&gt;</code></td>
<td>Start checking from this path.</td>
</tr>
<tr>
<td><code>-move</code></td>
<td>Move corrupted files to /lost+found</td>
</tr>
<tr>
<td><code>-delete</code></td>
<td>Delete corrupted files.</td>
</tr>
<tr>
<td><code>-openforwrite</code></td>
<td>Print out files opened for write.</td>
</tr>
<tr>
<td><code>-files</code></td>
<td>Print out files being checked.</td>
</tr>
<tr>
<td><code>-blocks</code></td>
<td>Print out block report.</td>
</tr>
<tr>
<td><code>-locations</code></td>
<td>Print out locations for every block.</td>
</tr>
<tr>
<td><code>-racks</code></td>
<td>Print out network topology for data-node locations.</td>
</tr>
</table>
</section>
<section>
<title> jar </title>
<p>
Runs a jar file. Users can bundle their Map Reduce code in a jar file and execute it using this command.
</p>
<p>
<code>Usage: hadoop jar &lt;jar&gt; [mainClass] args...</code>
</p>
<p>
The streaming jobs are run via this command. For examples, see
<a href="ext:streaming">Hadoop Streaming</a>.
</p>
<p>
The WordCount example is also run using jar command. For examples, see the
<a href="ext:mapred-tutorial">MapReduce Tutorial</a>.
</p>
</section>
<section>
<title> job </title>
<p>
Command to interact with Map Reduce Jobs.
</p>
<p>
<code>Usage: hadoop job [</code><a href="commands_manual.html#Generic+Options">GENERIC_OPTIONS</a><code>]
[-submit &lt;job-file&gt;] | [-status &lt;job-id&gt;] |
[-counter &lt;job-id&gt; &lt;group-name&gt; &lt;counter-name&gt;] | [-kill &lt;job-id&gt;] |
[-events &lt;job-id&gt; &lt;from-event-#&gt; &lt;#-of-events&gt;] | [-history [all] &lt;historyFile&gt;] |
[-list [all]] | [-kill-task &lt;task-id&gt;] | [-fail-task &lt;task-id&gt;] |
[-set-priority &lt;job-id&gt; &lt;priority&gt;]</code>
</p>
<table>
<tr><th> COMMAND_OPTION </th><th> Description </th></tr>
<tr>
<td><code>-submit &lt;job-file&gt;</code></td>
<td>Submits the job.</td>
</tr>
<tr>
<td><code>-status &lt;job-id&gt;</code></td>
<td>Prints the map and reduce completion percentage and all job counters.</td>
</tr>
<tr>
<td><code>-counter &lt;job-id&gt; &lt;group-name&gt; &lt;counter-name&gt;</code></td>
<td>Prints the counter value.</td>
</tr>
<tr>
<td><code>-kill &lt;job-id&gt;</code></td>
<td>Kills the job.</td>
</tr>
<tr>
<td><code>-events &lt;job-id&gt; &lt;from-event-#&gt; &lt;#-of-events&gt;</code></td>
<td>Prints the events' details received by jobtracker for the given range.</td>
</tr>
<tr>
<td><code>-history [all] &lt;historyFile&gt;</code></td>
<td>-history &lt;historyFile&gt; prints job details, failed and killed tip details. More details
about the job such as successful tasks and task attempts made for each task can be viewed by
specifying the [all] option. </td>
</tr>
<tr>
<td><code>-list [all]</code></td>
<td>-list all displays all jobs. -list displays only jobs which are yet to complete.</td>
</tr>
<tr>
<td><code>-kill-task &lt;task-id&gt;</code></td>
<td>Kills the task. Killed tasks are NOT counted against failed attempts.</td>
</tr>
<tr>
<td><code>-fail-task &lt;task-id&gt;</code></td>
<td>Fails the task. Failed tasks are counted against failed attempts.</td>
</tr>
<tr>
<td><code>-set-priority &lt;job-id&gt; &lt;priority&gt;</code></td>
<td>Changes the priority of the job.
Allowed priority values are VERY_HIGH, HIGH, NORMAL, LOW, VERY_LOW</td>
</tr>
</table>
</section>
<section>
<title> pipes </title>
<p>
Runs a pipes job.
</p>
<p>
<code>Usage: hadoop pipes [-conf &lt;path&gt;] [-jobconf &lt;key=value&gt;, &lt;key=value&gt;, ...]
[-input &lt;path&gt;] [-output &lt;path&gt;] [-jar &lt;jar file&gt;] [-inputformat &lt;class&gt;]
[-map &lt;class&gt;] [-partitioner &lt;class&gt;] [-reduce &lt;class&gt;] [-writer &lt;class&gt;]
[-program &lt;executable&gt;] [-reduces &lt;num&gt;] </code>
</p>
<table>
<tr><th> COMMAND_OPTION </th><th> Description </th></tr>
<tr>
<td><code>-conf &lt;path&gt;</code></td>
<td>Configuration for job</td>
</tr>
<tr>
<td><code>-jobconf &lt;key=value&gt;, &lt;key=value&gt;, ...</code></td>
<td>Add/override configuration for job</td>
</tr>
<tr>
<td><code>-input &lt;path&gt;</code></td>
<td>Input directory</td>
</tr>
<tr>
<td><code>-output &lt;path&gt;</code></td>
<td>Output directory</td>
</tr>
<tr>
<td><code>-jar &lt;jar file&gt;</code></td>
<td>Jar filename</td>
</tr>
<tr>
<td><code>-inputformat &lt;class&gt;</code></td>
<td>InputFormat class</td>
</tr>
<tr>
<td><code>-map &lt;class&gt;</code></td>
<td>Java Map class</td>
</tr>
<tr>
<td><code>-partitioner &lt;class&gt;</code></td>
<td>Java Partitioner</td>
</tr>
<tr>
<td><code>-reduce &lt;class&gt;</code></td>
<td>Java Reduce class</td>
</tr>
<tr>
<td><code>-writer &lt;class&gt;</code></td>
<td>Java RecordWriter</td>
</tr>
<tr>
<td><code>-program &lt;executable&gt;</code></td>
<td>Executable URI</td>
</tr>
<tr>
<td><code>-reduces &lt;num&gt;</code></td>
<td>Number of reduces</td>
</tr>
</table>
</section>
<section>
<title> queue </title>
<p>
command to interact and view Job Queue information
</p>
<p>
<code>Usage : hadoop queue [-list] | [-info &lt;job-queue-name&gt; [-showJobs]] | [-showacls]</code>
</p>
<table>
<tr>
<th> COMMAND_OPTION </th><th> Description </th>
</tr>
<tr>
<td><anchor id="QueuesList"/><code>-list</code> </td>
<td>Gets list of Job Queues configured in the system. Along with scheduling information
associated with the job queues.
</td>
</tr>
<tr>
<td><anchor id="QueuesInfo"/><code>-info &lt;job-queue-name&gt; [-showJobs]</code></td>
<td>
Displays the job queue information and associated scheduling information of particular
job queue. If -showJobs options is present a list of jobs submitted to the particular job
queue is displayed.
</td>
</tr>
<tr>
<td><code>-showacls</code></td>
<td>Displays the queue name and associated queue operations allowed for the current user.
The list consists of only those queues to which the user has access.
</td>
</tr>
</table>
</section>
<section>
<title> version </title>
<p>
Prints the version.
</p>
<p>
<code>Usage: hadoop version</code>
</p>
</section>
<section>
<title> CLASSNAME </title>
<p>
Hadoop script can be used to invoke any class.
</p>
<p>
Runs the class named CLASSNAME.
</p>
<p>
<code>Usage: hadoop CLASSNAME</code>
</p>
</section>
</section>
<section>
<title> Administration Commands </title>
<p>Commands useful for administrators of a Hadoop cluster.</p>
<section>
<title> balancer </title>
<p>
Runs a cluster balancing utility. An administrator can simply press Ctrl-C to stop the
rebalancing process. For more details see
<a href="http://hadoop.apache.org/hdfs/docs/current/hdfs_user_guide.html#Rebalancer">Rebalancer</a>.
</p>
<p>
<code>Usage: hadoop balancer [-threshold &lt;threshold&gt;]</code>
</p>
<table>
<tr><th> COMMAND_OPTION </th><th> Description </th></tr>
<tr>
<td><code>-threshold &lt;threshold&gt;</code></td>
<td>Percentage of disk capacity. This overwrites the default threshold.</td>
</tr>
</table>
</section>
<section>
<title> daemonlog </title>
<p>
Get/Set the log level for each daemon.
</p>
<p>
<code>Usage: hadoop daemonlog -getlevel &lt;host:port&gt; &lt;name&gt;</code><br/>
<code>Usage: hadoop daemonlog -setlevel &lt;host:port&gt; &lt;name&gt; &lt;level&gt;</code>
</p>
<table>
<tr><th> COMMAND_OPTION </th><th> Description </th></tr>
<tr>
<td><code>-getlevel &lt;host:port&gt; &lt;name&gt;</code></td>
<td>Prints the log level of the daemon running at &lt;host:port&gt;.
This command internally connects to http://&lt;host:port&gt;/logLevel?log=&lt;name&gt;</td>
</tr>
<tr>
<td><code>-setlevel &lt;host:port&gt; &lt;name&gt; &lt;level&gt;</code></td>
<td>Sets the log level of the daemon running at &lt;host:port&gt;.
This command internally connects to http://&lt;host:port&gt;/logLevel?log=&lt;name&gt;</td>
</tr>
</table>
</section>
<section>
<title> datanode</title>
<p>
Runs a HDFS datanode.
</p>
<p>
<code>Usage: hadoop datanode [-rollback]</code>
</p>
<table>
<tr><th> COMMAND_OPTION </th><th> Description </th></tr>
<tr>
<td><code>-rollback</code></td>
<td>Rollsback the datanode to the previous version. This should be used after stopping the datanode
and distributing the old Hadoop version.</td>
</tr>
</table>
</section>
<section>
<title> dfsadmin </title>
<p>
Runs a HDFS dfsadmin client.
</p>
<p>
<code>Usage: hadoop dfsadmin [</code><a href="commands_manual.html#Generic+Options">GENERIC_OPTIONS</a><code>] [-report] [-safemode enter | leave | get | wait] [-refreshNodes]
[-finalizeUpgrade] [-upgradeProgress status | details | force] [-metasave filename]
[-setQuota &lt;quota&gt; &lt;dirname&gt;...&lt;dirname&gt;] [-clrQuota &lt;dirname&gt;...&lt;dirname&gt;]
[-restoreFailedStorage true|false|check]
[-help [cmd]]</code>
</p>
<table>
<tr><th> COMMAND_OPTION </th><th> Description </th></tr>
<tr>
<td><code>-report</code></td>
<td>Reports basic filesystem information and statistics.</td>
</tr>
<tr>
<td><code>-safemode enter | leave | get | wait</code></td>
<td>Safe mode maintenance command.
Safe mode is a Namenode state in which it <br/>
1. does not accept changes to the name space (read-only) <br/>
2. does not replicate or delete blocks. <br/>
Safe mode is entered automatically at Namenode startup, and
leaves safe mode automatically when the configured minimum
percentage of blocks satisfies the minimum replication
condition. Safe mode can also be entered manually, but then
it can only be turned off manually as well.</td>
</tr>
<tr>
<td><code>-refreshNodes</code></td>
<td>Re-read the hosts and exclude files to update the set
of Datanodes that are allowed to connect to the Namenode
and those that should be decommissioned or recommissioned.</td>
</tr>
<tr>
<td><code>-finalizeUpgrade</code></td>
<td>Finalize upgrade of HDFS.
Datanodes delete their previous version working directories,
followed by Namenode doing the same.
This completes the upgrade process.</td>
</tr>
<tr>
<td><code>-printTopology</code></td>
<td>Print a tree of the rack/datanode topology of the
cluster as seen by the NameNode.</td>
</tr>
<tr>
<td><code>-upgradeProgress status | details | force</code></td>
<td>Request current distributed upgrade status,
a detailed status or force the upgrade to proceed.</td>
</tr>
<tr>
<td><code>-metasave filename</code></td>
<td>Save Namenode's primary data structures
to &lt;filename&gt; in the directory specified by hadoop.log.dir property.
&lt;filename&gt; will contain one line for each of the following <br/>
1. Datanodes heart beating with Namenode<br/>
2. Blocks waiting to be replicated<br/>
3. Blocks currrently being replicated<br/>
4. Blocks waiting to be deleted</td>
</tr>
<tr>
<td><code>-setQuota &lt;quota&gt; &lt;dirname&gt;...&lt;dirname&gt;</code></td>
<td>Set the quota &lt;quota&gt; for each directory &lt;dirname&gt;.
The directory quota is a long integer that puts a hard limit on the number of names in the directory tree.<br/>
Best effort for the directory, with faults reported if<br/>
1. N is not a positive integer, or<br/>
2. user is not an administrator, or<br/>
3. the directory does not exist or is a file, or<br/>
4. the directory would immediately exceed the new quota.</td>
</tr>
<tr>
<td><code>-clrQuota &lt;dirname&gt;...&lt;dirname&gt;</code></td>
<td>Clear the quota for each directory &lt;dirname&gt;.<br/>
Best effort for the directory. with fault reported if<br/>
1. the directory does not exist or is a file, or<br/>
2. user is not an administrator.<br/>
It does not fault if the directory has no quota.</td>
</tr>
<tr>
<td><code>-restoreFailedStorage true | false | check</code></td>
<td>This option will turn on/off automatic attempt to restore failed storage replicas.
If a failed storage becomes available again the system will attempt to restore
edits and/or fsimage during checkpoint. 'check' option will return current setting.</td>
</tr>
<tr>
<td><code>-help [cmd]</code></td>
<td> Displays help for the given command or all commands if none
is specified.</td>
</tr>
</table>
</section>
<section>
<title>mradmin</title>
<p>Runs MR admin client</p>
<p><code>Usage: hadoop mradmin [</code>
<a href="commands_manual.html#Generic+Options">GENERIC_OPTIONS</a>
<code>] [-refreshServiceAcl] [-refreshQueues] [-refreshNodes] [-help [cmd]] </code></p>
<table>
<tr>
<th> COMMAND_OPTION </th><th> Description </th>
</tr>
<tr>
<td><code>-refreshServiceAcl</code></td>
<td> Reload the service-level authorization policies. Jobtracker
will reload the authorization policy file.</td>
</tr>
<tr>
<td><anchor id="RefreshQueues"/><code>-refreshQueues</code></td>
<td><p> Reload the queues' configuration at the JobTracker.
Most of the configuration of the queues can be refreshed/reloaded
without restarting the Map/Reduce sub-system. Administrators
typically own the
<a href="cluster_setup.html#mapred-queues.xml">
<em>conf/mapred-queues.xml</em></a>
file, can edit it while the JobTracker is still running, and can do
a reload by running this command.</p>
<p>It should be noted that while trying to refresh queues'
configuration, one cannot change the hierarchy of queues itself.
This means no operation that involves a change in either the
hierarchy structure itself or the queues' names will be allowed.
Only selected properties of queues can be changed during refresh.
For example, new queues cannot be added dynamically, neither can an
existing queue be deleted.</p>
<p>If during a reload of queue configuration,
a syntactic or semantic error in made during the editing of the
configuration file, the refresh command fails with an exception that
is printed on the standard output of this command, thus informing the
requester with any helpful messages of what has gone wrong during
the edit/reload. Importantly, the existing queue configuration is
untouched and the system is left in a consistent state.
</p>
<p>As described in the
<a href="cluster_setup.html#mapred-queues.xml"><em>
conf/mapred-queues.xml</em></a> section, the
<a href="cluster_setup.html#properties_tag"><em>
&lt;properties&gt;</em></a> tag in the queue configuration file can
also be used to specify per-queue properties needed by the scheduler.
When the framework's queue configuration is reloaded using this
command, this scheduler specific configuration will also be reloaded
, provided the scheduler being configured supports this reload.
Please see the documentation of the particular scheduler in use.</p>
</td>
</tr>
<tr>
<td><code>-refreshNodes</code></td>
<td> Refresh the hosts information at the jobtracker.</td>
</tr>
<tr>
<td><code>-help [cmd]</code></td>
<td>Displays help for the given command or all commands if none
is specified.</td>
</tr>
</table>
</section>
<section>
<title> jobtracker </title>
<p>
Runs the MapReduce job Tracker node.
</p>
<p>
<code>Usage: hadoop jobtracker [-dumpConfiguration]</code>
</p>
<table>
<tr>
<th>COMMAND_OPTION</th><th> Description</th>
</tr>
<tr>
<td><code>-dumpConfiguration</code></td>
<td> Dumps the configuration used by the JobTracker alongwith queue
configuration in JSON format into Standard output used by the
jobtracker and exits.</td>
</tr>
</table>
</section>
<section>
<title> namenode </title>
<p>
Runs the namenode. For more information about upgrade, rollback and finalize see
<a href="http://hadoop.apache.org/hdfs/docs/current/hdfs_user_guide.html#Upgrade+and+Rollback">Upgrade and Rollback</a>.
</p>
<p>
<code>Usage: hadoop namenode [-format] | [-upgrade] | [-rollback] | [-finalize] | [-importCheckpoint] | [-checkpoint] | [-backup]</code>
</p>
<table>
<tr><th> COMMAND_OPTION </th><th> Description </th></tr>
<tr>
<td><code>-regular</code></td>
<td>Start namenode in standard, active role rather than as backup or checkpoint node. This is the default role.</td>
</tr>
<tr>
<td><code>-checkpoint</code></td>
<td>Start namenode in checkpoint role, creating periodic checkpoints of the active namenode metadata.</td>
</tr>
<tr>
<td><code>-backup</code></td>
<td>Start namenode in backup role, maintaining an up-to-date in-memory copy of the namespace and creating periodic checkpoints.</td>
</tr>
<tr>
<td><code>-format</code></td>
<td>Formats the namenode. It starts the namenode, formats it and then shut it down.</td>
</tr>
<tr>
<td><code>-upgrade</code></td>
<td>Namenode should be started with upgrade option after the distribution of new Hadoop version.</td>
</tr>
<tr>
<td><code>-rollback</code></td>
<td>Rollsback the namenode to the previous version. This should be used after stopping the cluster
and distributing the old Hadoop version.</td>
</tr>
<tr>
<td><code>-finalize</code></td>
<td>Finalize will remove the previous state of the files system. Recent upgrade will become permanent.
Rollback option will not be available anymore. After finalization it shuts the namenode down.</td>
</tr>
<tr>
<td><code>-importCheckpoint</code></td>
<td>Loads image from a checkpoint directory and saves it into the current one. Checkpoint directory
is read from property fs.checkpoint.dir
(see <a href="http://hadoop.apache.org/hdfs/docs/current/hdfs_user_guide.html#Import+checkpoint">Import Checkpoint</a>).
</td>
</tr>
<tr>
<td><code>-checkpoint</code></td>
<td>Enables checkpointing
(see <a href="http://hadoop.apache.org/hdfs/docs/current/hdfs_user_guide.html#Checkpoint+Node">Checkpoint Node</a>).</td>
</tr>
<tr>
<td><code>-backup</code></td>
<td>Enables checkpointing and maintains an in-memory, up-to-date copy of the file system namespace
(see <a href="http://hadoop.apache.org/hdfs/docs/current/hdfs_user_guide.html#Backup+Node">Backup Node</a>).</td>
</tr>
</table>
</section>
<section>
<title> secondarynamenode </title>
<note>
The Secondary NameNode has been deprecated. Instead, consider using the
<a href="http://hadoop.apache.org/hdfs/docs/current/hdfs_user_guide.html#Checkpoint+Node">Checkpoint Node</a> or
<a href="http://hadoop.apache.org/hdfs/docs/current/hdfs_user_guide.html#Backup+Node">Backup Node</a>.
</note>
<p>
Runs the HDFS secondary
namenode. See <a href="http://hadoop.apache.org/hdfs/docs/current/hdfs_user_guide.html#Secondary+NameNode">Secondary NameNode</a>
for more info.
</p>
<p>
<code>Usage: hadoop secondarynamenode [-checkpoint [force]] | [-geteditsize]</code>
</p>
<table>
<tr><th> COMMAND_OPTION </th><th> Description </th></tr>
<tr>
<td><code>-checkpoint [force]</code></td>
<td>Checkpoints the Secondary namenode if EditLog size >= fs.checkpoint.size.
If -force is used, checkpoint irrespective of EditLog size.</td>
</tr>
<tr>
<td><code>-geteditsize</code></td>
<td>Prints the EditLog size.</td>
</tr>
</table>
</section>
<section>
<title> tasktracker </title>
<p>
Runs a MapReduce task Tracker node.
</p>
<p>
<code>Usage: hadoop tasktracker</code>
</p>
</section>
</section>
</body>
</document>

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</section>
<section>
<section id="Download">
<title>Download</title>
<p>

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@ -39,10 +39,12 @@ See http://forrest.apache.org/docs/linking.html for more info.
</docs>
<docs label="Guides">
<commands_manual label="Hadoop Commands" href="commands_manual.html" />
<fsshell label="File System Shell" href="file_system_shell.html" />
<SLA label="Service Level Authorization" href="service_level_auth.html"/>
<native_lib label="Native Libraries" href="native_libraries.html" />
<superusers label="Superusers Acting On Behalf Of Other Users" href="Superusers.html"/>
<hod_scheduler label="Hadoop On Demand" href="hod_scheduler.html"/>
</docs>
<docs label="Miscellaneous">
@ -69,6 +71,15 @@ See http://forrest.apache.org/docs/linking.html for more info.
<hdfs-default href="http://hadoop.apache.org/hdfs/docs/current/hdfs-default.html" />
<mapred-default href="http://hadoop.apache.org/mapreduce/docs/current/mapred-default.html" />
<mapred-queues href="http://hadoop.apache.org/mapreduce/docs/current/mapred_queues.xml" />
<capacity-scheduler href="http://hadoop.apache.org/mapreduce/docs/current/capacity_scheduler.html" />
<mapred-tutorial href="http://hadoop.apache.org/mapreduce/docs/current/mapred_tutorial.html" >
<JobAuthorization href="#Job+Authorization" />
</mapred-tutorial>
<streaming href="http://hadoop.apache.org/mapreduce/docs/current/streaming.html" />
<distcp href="http://hadoop.apache.org/mapreduce/docs/current/distcp.html" />
<hadoop-archives href="http://hadoop.apache.org/mapreduce/docs/current/hadoop_archives.html" />
<zlib href="http://www.zlib.net/" />
<gzip href="http://www.gzip.org/" />
<bzip href="http://www.bzip.org/" />