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class="DEVICENAME">/dev/ccd0c</tt>. The <tt class="FILENAME">/dev/</tt> portion is
optional.</dd>

<dt><a href="raid.html#CO-CCD-INTERLEAVE"><img src="./imagelib/callouts/2.png" hspace="0"
vspace="0" border="0" alt="(2)" /></a></dt>

<dd>The interleave for the file system. The interleave defines the size of a stripe in
disk blocks, each normally 512 bytes. So, an interleave of 32 would be 16,384 bytes.</dd>

<dt><a href="raid.html#CO-CCD-FLAGS"><img src="./imagelib/callouts/3.png" hspace="0"
vspace="0" border="0" alt="(3)" /></a></dt>

<dd>Flags for <span class="CITEREFENTRY"><span
class="REFENTRYTITLE">ccdconfig</span>(8)</span>. If you want to enable drive mirroring,
you can specify a flag here. This configuration does not provide mirroring for <span
class="CITEREFENTRY"><span class="REFENTRYTITLE">ccd</span>(4)</span>, so it is set at 0
(zero).</dd>

<dt><a href="raid.html#CO-CCD-DEVS"><img src="./imagelib/callouts/4.png" hspace="0"
vspace="0" border="0" alt="(4)" /></a></dt>

<dd>The final arguments to <span class="CITEREFENTRY"><span
class="REFENTRYTITLE">ccdconfig</span>(8)</span> are the devices to place into the array.
Use the complete pathname for each device.</dd>
</dl>
</div>

<p>After running <span class="CITEREFENTRY"><span
class="REFENTRYTITLE">ccdconfig</span>(8)</span> the <span class="CITEREFENTRY"><span
class="REFENTRYTITLE">ccd</span>(4)</span> is configured. A file system can be installed.
Refer to <span class="CITEREFENTRY"><span class="REFENTRYTITLE">newfs</span>(8)</span>
for options, or simply run:</p>

<pre class="PROGRAMLISTING">
newfs /dev/ccd0c
</pre>
</div>

<div class="SECT4">
<h4 class="SECT4"><a id="CCD-AUTO" name="CCD-AUTO">12.4.1.1.4. Making it All
Automatic</a></h4>

<p>Generally, you will want to mount the <span class="CITEREFENTRY"><span
class="REFENTRYTITLE">ccd</span>(4)</span> upon each reboot. To do this, you must
configure it first. Write out your current configuration to <tt
class="FILENAME">/etc/ccd.conf</tt> using the following command:</p>

<pre class="PROGRAMLISTING">
ccdconfig -g &gt; /etc/ccd.conf
</pre>

<p>During reboot, the script <tt class="COMMAND">/etc/rc</tt> runs <tt
class="COMMAND">ccdconfig -C</tt> if <tt class="FILENAME">/etc/ccd.conf</tt> exists. This
automatically configures the <span class="CITEREFENTRY"><span
class="REFENTRYTITLE">ccd</span>(4)</span> so it can be mounted.</p>

<div class="NOTE">
<blockquote class="NOTE">
<p><b>Note:</b> If you are booting into single user mode, before you can <span
class="CITEREFENTRY"><span class="REFENTRYTITLE">mount</span>(8)</span> the <span
class="CITEREFENTRY"><span class="REFENTRYTITLE">ccd</span>(4)</span>, you need to issue
the following command to configure the array:</p>

<pre class="PROGRAMLISTING">
ccdconfig -C
</pre>
</blockquote>
</div>

<p>To automatically mount the <span class="CITEREFENTRY"><span
class="REFENTRYTITLE">ccd</span>(4)</span>, place an entry for the <span
class="CITEREFENTRY"><span class="REFENTRYTITLE">ccd</span>(4)</span> in <tt
class="FILENAME">/etc/fstab</tt> so it will be mounted at boot time:</p>

<pre class="PROGRAMLISTING">
/dev/ccd0c              /media       ufs     rw      2       2
</pre>
</div>
</div>

<div class="SECT3">
<h3 class="SECT3"><a id="VINUM" name="VINUM">12.4.1.2. The Vinum Volume Manager</a></h3>

<p>The Vinum Volume Manager is a block device driver which implements virtual disk
drives. It isolates disk hardware from the block device interface and maps data in ways
which result in an increase in flexibility, performance and reliability compared to the
traditional slice view of disk storage. <span class="CITEREFENTRY"><span
class="REFENTRYTITLE">vinum</span>(8)</span> implements the RAID-0, RAID-1 and RAID-5
models, both individually and in combination.</p>

<p>See <a href="vinum-vinum.html">Chapter 13</a> for more information about <span
class="CITEREFENTRY"><span class="REFENTRYTITLE">vinum</span>(8)</span>.</p>
</div>
</div>

<div class="SECT2">
<h2 class="SECT2"><a id="RAID-HARD" name="RAID-HARD">12.4.2. Hardware RAID</a></h2>

<p>FreeBSD also supports a variety of hardware <acronym class="ACRONYM">RAID</acronym>
controllers. These devices control a <acronym class="ACRONYM">RAID</acronym> subsystem
without the need for FreeBSD specific software to manage the array.</p>

<p>Using an on-card <acronym class="ACRONYM">BIOS</acronym>, the card controls most of
the disk operations itself. The following is a brief setup description using a <acronym
class="ACRONYM">Promise IDE RAID</acronym> controller. When this card is installed and
the system is started up, it displays a prompt requesting information. Follow the
instructions to enter the card's setup screen. From here, you have the ability to combine
all the attached drives. After doing so, the disk(s) will look like a single drive to
FreeBSD. Other <acronym class="ACRONYM">RAID</acronym> levels can be set up
accordingly.</p>
</div>

<div class="SECT2">
<h2 class="SECT2"><a id="AEN16950" name="AEN16950">12.4.3. Rebuilding ATA RAID1
Arrays</a></h2>

<p>FreeBSD allows you to hot-replace a failed disk in an array. This requires that you
catch it before you reboot.</p>

<p>You will probably see something like the following in <tt
class="FILENAME">/var/log/messages</tt> or in the <span class="CITEREFENTRY"><span
class="REFENTRYTITLE">dmesg</span>(8)</span> output:</p>

<pre class="PROGRAMLISTING">
ad6 on monster1 suffered a hard error.
ad6: READ command timeout tag=0 serv=0 - resetting
ad6: trying fallback to PIO mode
ata3: resetting devices .. done
ad6: hard error reading fsbn 1116119 of 0-7 (ad6 bn 1116119; cn 1107 tn 4 sn 11) status=59 error=40
ar0: WARNING - mirror lost
</pre>

<p>Using <span class="CITEREFENTRY"><span
class="REFENTRYTITLE">atacontrol</span>(8)</span>, check for further information:</p>

<pre class="SCREEN">
<samp class="PROMPT">#</samp> <kbd class="USERINPUT">atacontrol list</kbd>
ATA channel 0:
    Master:      no device present
    Slave:   acd0 &lt;HL-DT-ST CD-ROM GCR-8520B/1.00&gt; ATA/ATAPI rev 0

ATA channel 1:
    Master:      no device present
    Slave:       no device present

ATA channel 2:
    Master:  ad4 &lt;MAXTOR 6L080J4/A93.0500&gt; ATA/ATAPI rev 5
    Slave:       no device present

ATA channel 3:
    Master:  ad6 &lt;MAXTOR 6L080J4/A93.0500&gt; ATA/ATAPI rev 5
    Slave:       no device present

<samp class="PROMPT">#</samp> <kbd class="USERINPUT">atacontrol status ar0</kbd>
ar0: ATA RAID1 subdisks: ad4 ad6 status: DEGRADED
</pre>

<div class="PROCEDURE">
<ol type="1">
<li>
<p>You will first need to detach the disk from the array so that you can safely remove
it:</p>

<pre class="SCREEN">
<samp class="PROMPT">#</samp> <kbd class="USERINPUT">atacontrol detach 3</kbd>
</pre>
</li>

<li>
<p>Replace the disk.</p>
</li>

<li>
<p>Reattach the disk as a spare:</p>

<pre class="SCREEN">
<samp class="PROMPT">#</samp> <kbd class="USERINPUT">atacontrol attach 3</kbd>
Master:  ad6 &lt;MAXTOR 6L080J4/A93.0500&gt; ATA/ATAPI rev 5
Slave:   no device present
</pre>
</li>

<li>
<p>Rebuild the array:</p>

<pre class="SCREEN">
<samp class="PROMPT">#</samp> <kbd class="USERINPUT">atacontrol rebuild ar0</kbd>
</pre>
</li>

<li>
<p>The rebuild command hangs until complete. However, it is possible to open another
terminal (using <b class="KEYCAP">Alt</b>+<b class="KEYCAP">F<var
class="REPLACEABLE">n</var></b>) and check on the progress by issuing the following
command:</p>

<pre class="SCREEN">
<samp class="PROMPT">#</samp> <kbd class="USERINPUT">dmesg | tail -10</kbd>
[output removed]
ad6: removed from configuration
ad6: deleted from ar0 disk1
ad6: inserted into ar0 disk1 as spare

<samp class="PROMPT">#</samp> <kbd class="USERINPUT">atacontrol status ar0</kbd>
ar0: ATA RAID1 subdisks: ad4 ad6 status: REBUILDING 0% completed
</pre>
</li>

<li>
<p>Wait until this operation completes.</p>
</li>
</ol>
</div>
</div>
</div>

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