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<h1>Creating logical devices &gt; advanced settings</h1>
<p><b><img src="images/note.gif" width="15" height="17"> Note:</b> Not all options
  are available for all RAID levels.</p>
<p>Use the <strong>Advanced settings</strong> in the Configuration wizard to tune
  your logical device configuration for optimal performance. You can set the following
  options:
<ul>
  <li><strong>Write cache</strong> - Determines how data is stored in the controller's
    cache memory. You can choose from two available settings: <a href="cwrcache.htm">write-through</a>
    and <a href="cwrcache.htm">write-back</a>.<br>
    <br>
  </li>
  <li><strong>stripe size</strong> - Determines the amount of data, in kilobytes
    (KB), written to one <a href="gsegment.htm">segment</a> of a logical device
    before the next segment is used for subsequent data. Depending on the controller, you can choose a stripe size from 16 KB to 1024 KB.<br>
    <br>
    <b><img src="images/note.gif" width="15" height="17"> Notes:</b>
    <ol><li>The default stripe size usually provides the best performance for typical applications.<BR></li>

    <li>
    To change the stripe size of an existing logical device, you must <a href="aexpldcc.htm">expand</a> or <a href="achgrlcc.htm">migrate</a> the logical device.
<br></li>
    <li>For RAID Level-6 and Level-60 logical devices,
    the number of choices for stripe size decreases as the number of disks in the logical device increases.</li>
    </ol>
  </li>
  <li><strong>Read cache</strong> - Enables and disables read caching. When read-caching
    is enabled, the controller monitors read access to the logical device. If it
    detects a pattern, it pre-loads the cache with the data that seems most likely
    to be read next. The default is Enabled. <br>
    <br>
  </li>
  <li><strong>Initialize method</strong> - Determines the method used to initialize
    the logical device. You can choose from three available methods:<br>
    <br>
    <ul>
      <li><strong>Build</strong> - For RAID Level-1 logical devices,
        copies the data from the primary drive to the mirror drive. For RAID Level-5
        logical devices, computes and writes the correct parity for the entire
        logical device. <br>
        <br>
        <br>
        <b><img src="images/note.gif" width="15" height="17"> Note:</b> Build
        can be a lengthy operation. The HP Storage Manager performs this task in
        the background. However, you cannot use the logical device until the task
        is complete. <br>
        <br>
      </li>
      <li><strong>Clear</strong> - removes pre-existing data by overwriting every
        block in the logical device. This method is faster than build
        but the logical device is not available immediately. <br>
        <br>
        <img src="images/hstraid1.gif" width="37" height="32">&nbsp;For HostRAID
        controllers, the HP Storage Manager supports the Clear initialization method
        only. <br>
      </li>
      <li><strong>Quick</strong> - makes the logical device available immediately.
        It is the fastest method but should be used only for <em>new</em> physical
        disks.<br>
        <br>
      </li>
    </ul>
  </li>
  <li><strong>Initialize priority</strong> - Adjusts the priority of the initialization
    task. The default is High: initialize the logical device as fast as possible.<br>
  </li>
</ul>
<p>When you are ready to continue, click <strong>Next</strong>. The &quot;<a href="wsummcc.htm">Configuration
  summary</a>&quot; window opens.<br>
</p>
<h2>More information</h2>

<ul>
  <li><a href="cstripe.htm">Understanding stripe size</a></li>
  <li><a href="cwrcache.htm">Understanding write-cache mode for logical devices</a></li>
  <li><a href="csynchld.htm">Understanding logical-drive verification</a></li>
</ul>

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