<div id="docs-body">
 <div class="section">
  <div class="titlepage">
   <div>
    <div>
     <h3 class="title">
      <a name="mysql-cluster-configuration-overview">
      </a>
      25.4.2 Overview of NDB Cluster Configuration Parameters, Options, and Variables
     </h3>
    </div>
   </div>
  </div>
  <div class="toc">
   <dl class="toc">
    <dt>
     <span class="section">
      <a href="mysql-cluster-params-ndbd.html">
       25.4.2.1 NDB Cluster Data Node Configuration Parameters
      </a>
     </span>
    </dt>
    <dt>
     <span class="section">
      <a href="mysql-cluster-params-mgmd.html">
       25.4.2.2 NDB Cluster Management Node Configuration Parameters
      </a>
     </span>
    </dt>
    <dt>
     <span class="section">
      <a href="mysql-cluster-params-api.html">
       25.4.2.3 NDB Cluster SQL Node and API Node Configuration Parameters
      </a>
     </span>
    </dt>
    <dt>
     <span class="section">
      <a href="mysql-cluster-params-other.html">
       25.4.2.4 Other NDB Cluster Configuration Parameters
      </a>
     </span>
    </dt>
    <dt>
     <span class="section">
      <a href="mysql-cluster-option-tables.html">
       25.4.2.5 NDB Cluster mysqld Option and Variable Reference
      </a>
     </span>
    </dt>
   </dl>
  </div>
  <a class="indexterm" name="idm46045121945056">
  </a>
  <a class="indexterm" name="idm46045121943600">
  </a>
  <p>
   The next several sections provide summary tables of NDB Cluster
      node configuration parameters used in the
   <code class="filename">
    config.ini
   </code>
   file to govern various aspects of
      node behavior, as well as of options and variables read by
   <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server">
    <span class="command">
     <strong>
      mysqld
     </strong>
    </span>
   </a>
   from a
   <code class="filename">
    my.cnf
   </code>
   file
      or from the command line when run as an NDB Cluster process. Each
      of the node parameter tables lists the parameters for a given type
      (
   <code class="literal">
    ndbd
   </code>
   ,
   <code class="literal">
    ndb_mgmd
   </code>
   ,
   <code class="literal">
    mysqld
   </code>
   ,
   <code class="literal">
    computer
   </code>
   ,
   <code class="literal">
    tcp
   </code>
   , or
   <code class="literal">
    shm
   </code>
   ). All tables
      include the data type for the parameter, option, or variable, as
      well as its default, minimum, and maximum values as applicable.
  </p>
  <p>
   <b>
    Considerations when restarting nodes.
   </b>
   For node parameters, these tables also indicate what type of
        restart is required (node restart or system restart)—and
        whether the restart must be done with
   <code class="option">
    --initial
   </code>
   —to change the value of a given
        configuration parameter. When performing a node restart or an
        initial node restart, all of the cluster's data nodes must
        be restarted in turn (also referred to as a
   <span class="firstterm">
    rolling restart
   </span>
   ). It is
        possible to update cluster configuration parameters marked as
   <code class="literal">
    node
   </code>
   online—that is, without shutting
        down the cluster—in this fashion. An initial node restart
        requires restarting each
   <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon">
    <span class="command">
     <strong>
      ndbd
     </strong>
    </span>
   </a>
   process with
        the
   <code class="option">
    --initial
   </code>
   option.
  </p>
  <p>
   A system restart requires a complete shutdown and restart of the
      entire cluster. An initial system restart requires taking a backup
      of the cluster, wiping the cluster file system after shutdown, and
      then restoring from the backup following the restart.
  </p>
  <p>
   In any cluster restart, all of the cluster's management servers
      must be restarted for them to read the updated configuration
      parameter values.
  </p>
  <div class="important" style="margin-left: 0.5in; margin-right: 0.5in;">
   <div class="admon-title">
    Important
   </div>
   <p>
    Values for numeric cluster parameters can generally be increased
        without any problems, although it is advisable to do so
        progressively, making such adjustments in relatively small
        increments. Many of these can be increased online, using a
        rolling restart.
   </p>
   <p>
    However, decreasing the values of such parameters—whether
        this is done using a node restart, node initial restart, or even
        a complete system restart of the cluster—is not to be
        undertaken lightly; it is recommended that you do so only after
        careful planning and testing. This is especially true with
        regard to those parameters that relate to memory usage and disk
        space, such as
    <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnooftables">
     <code class="literal">
      MaxNoOfTables
     </code>
    </a>
    ,
    <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnooforderedindexes">
     <code class="literal">
      MaxNoOfOrderedIndexes
     </code>
    </a>
    ,
        and
    <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofuniquehashindexes">
     <code class="literal">
      MaxNoOfUniqueHashIndexes
     </code>
    </a>
    .
        In addition, it is the generally the case that configuration
        parameters relating to memory and disk usage can be raised using
        a simple node restart, but they require an initial node restart
        to be lowered.
   </p>
  </div>
  <p>
   Because some of these parameters can be used for configuring more
      than one type of cluster node, they may appear in more than one of
      the tables.
  </p>
  <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
   <div class="admon-title">
    Note
   </div>
   <p>
    <code class="literal">
     4294967039
    </code>
    often appears as a maximum value
        in these tables. This value is defined in the
    <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4">
     <code class="literal">
      NDBCLUSTER
     </code>
    </a>
    sources as
    <code class="literal">
     MAX_INT_RNIL
    </code>
    and is equal to
    <code class="literal">
     0xFFFFFEFF
    </code>
    , or
    <code class="literal">
     2
     <sup>
      32
     </sup>
     −
        2
     <sup>
      8
     </sup>
     − 1
    </code>
    .
   </p>
  </div>
 </div>
 <br/>
</div>
