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<title>Understanding RAID level-0</title>

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<h1>Understanding RAID level-0 </h1>
<p>RAID level-0 <a href="gs-unit.htm">stripes</a> the data across all the drives
  in the pool. This offers substantial speed enhancement, but provides no data
  redundancy. RAID level-0 provides the largest storage capacity of the RAID levels
  that are offered, because no room is taken for redundant data or data-<a href="gparity.htm">parity</a>
  storage. </p>
<p> RAID level-0 requires a minimum of two drives and, depending upon the level
  of firmware and the <a href="cstripe.htm">stripe size</a>, supports a maximum
  of 48 drives.
<p> The following illustration shows an example of a RAID level-0 logical device.
<h2>RAID level-0 example</h2>
<table border="0" cellpadding="3">
  <tr valign=top>
    <td align="LEFT" valign="TOP" width="258">Start with two physical drives.
    </td>
    <td width="133"><img src="images/raidl0-a.gif" width="107" height="93" alt="RAID Level 0 example">
    </td>
  </tr>
  <tr valign=top>
    <td align="LEFT" valign="TOP" width="258">Create an pool using the two physical
      drives. </td>
    <td width="133"><img src="images/raidl0-b.gif" width="107" height="93" alt="RAID Level 0 example">
    </td>
  </tr>
  <tr valign=top>
    <td align="LEFT" valign="TOP" width="258">Then create a logical device within
      that pool. </td>
    <td width="133"><img src="images/raidl0-c.gif" width="107" height="93" alt="RAID Level 0 example">
    </td>
  </tr>
  <tr valign=top>
    <td align="LEFT" valign="TOP" width="258">The data is striped across the drives,
      creating blocks.
      <p>Notice that the data is striped across all the drives in the pool, but
        no redundant data is stored.
    </td>
    <td width="133"><img src="images/raidl0-d.gif" width="107" height="93" alt="RAID Level 0 example">
    </td>
  </tr>
</table>
<p>A physical drive failure within the pool results in loss of data in the logical
  drive assigned RAID level-0, but only in that logical device. If you have logical
  drives assigned <a href="craid1.htm">RAID level-1</a> or
  <a href="craid5.htm">5</a> in the same pool,
  they will not lose data. </p>

<p>When you replace a failed drive, the controller can rebuild all the
  RAID level-1 and 5 logical devices automatically onto the replacement
  physical drive. However, any data stored in a failed RAID level-0 logical device
  is lost.
<p>Although the risk of data loss is present, you might want to assign RAID level-0
  to one of the logical devices to take advantage of the speed this RAID level
  offers. You can use this logical device to store data that you back up each day
  and can re-create easily. You also might want to use a RAID level-0 logical
  drive when you require maximum capacity.
<p>RAID level-0 offers the following advantages and disadvantages. <br>
<table  BORDER>
  <tr bgcolor="#C0C0C0">
    <th align="LEFT" valign="BOTTOM" width="50%">Advantages </th>
    <th align="LEFT" valign="BOTTOM" width="50%">Disadvantages </th>
  </tr>
  <tr>
    <td align="LEFT" valign="TOP" width="50%">
      <ul>
        <li>Substantial speed enhancement </li>
        <li>Maximum utilization of physical drive storage capacity, because no
          room is taken for redundant data or data-parity storage </li>
      </ul>
    </td>
    <td align="LEFT" valign="TOP" width="50%">No data redundancy, resulting in
      data loss in the event that a physical drive fails </td>
  </tr>
</table>
<h2>More information</h2>

<ul>
  <li><a href="craidint.htm">Understanding RAID technology</a></li>
  <li><a href="cstripe.htm">Understanding stripe size</a></li>
  <li><a href="cselraid.htm">Selecting a RAID level</a> </li>
  <li><a href="craid1.htm">RAID level-1</a></li>
  <li><a href="craid5.htm">RAID level-5</a></li>
  <li><a href="craid6.htm">RAID level-6</a></li>
  <li><a href="craidx0.htm">RAID level-x0</a> </li>
  <li><a href="craidvol.htm">RAID volumes</a></li>
</ul>

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