svn commit: r44663 - head/en_US.ISO8859-1/books/handbook/geom

Dru Lavigne dru at FreeBSD.org
Fri Apr 25 15:26:07 UTC 2014


Author: dru
Date: Fri Apr 25 15:26:06 2014
New Revision: 44663
URL: http://svnweb.freebsd.org/changeset/doc/44663

Log:
  Put RAID3 chapter before Software RAID Devices chapter.
  
  Sponsored by:	iXsystems

Modified:
  head/en_US.ISO8859-1/books/handbook/geom/chapter.xml

Modified: head/en_US.ISO8859-1/books/handbook/geom/chapter.xml
==============================================================================
--- head/en_US.ISO8859-1/books/handbook/geom/chapter.xml	Fri Apr 25 14:48:46 2014	(r44662)
+++ head/en_US.ISO8859-1/books/handbook/geom/chapter.xml	Fri Apr 25 15:26:06 2014	(r44663)
@@ -842,6 +842,179 @@ mountroot></screen>
     </sect2>
   </sect1>
 
+  <sect1 xml:id="geom-raid3">
+    <info>
+
+      <title><acronym>RAID</acronym>3 - Byte-level Striping with
+	Dedicated Parity</title>
+
+      <authorgroup>
+	<author>
+	  <personname>
+	    <firstname>Mark</firstname>
+	    <surname>Gladman</surname>
+	  </personname>
+	  <contrib>Written by </contrib>
+	</author>
+
+	<author>
+	  <personname>
+	    <firstname>Daniel</firstname>
+	    <surname>Gerzo</surname>
+	  </personname>
+	</author>
+      </authorgroup>
+
+      <authorgroup>
+	<author>
+	  <personname>
+	    <firstname>Tom</firstname>
+	    <surname>Rhodes</surname>
+	  </personname>
+	  <contrib>Based on documentation by </contrib>
+	</author>
+
+	<author>
+	  <personname>
+	    <firstname>Murray</firstname>
+	    <surname>Stokely</surname>
+	  </personname>
+	</author>
+      </authorgroup>
+    </info>
+
+    <indexterm>
+      <primary><acronym>GEOM</acronym></primary>
+    </indexterm>
+    <indexterm>
+      <primary>RAID3</primary>
+    </indexterm>
+
+    <para><acronym>RAID</acronym>3 is a method used to combine several
+      disk drives into a single volume with a dedicated parity disk.
+      In a <acronym>RAID</acronym>3 system, data is split up into a
+      number of bytes that are written across all the drives in the
+      array except for one disk which acts as a dedicated parity disk.
+      This means that reading 1024KB from a
+      <acronym>RAID</acronym>3 implementation will access all disks in
+      the array.  Performance can be enhanced by using multiple disk
+      controllers.  The <acronym>RAID</acronym>3 array provides a
+      fault tolerance of 1 drive, while providing a capacity of 1 -
+      1/n times the total capacity of all drives in the array, where n
+      is the number of hard drives in the array.  Such a configuration
+      is mostly suitable for storing data of larger sizes such as
+      multimedia files.</para>
+
+    <para>At least 3 physical hard drives are required to build a
+      <acronym>RAID</acronym>3 array.  Each disk must be of the same
+      size, since I/O requests are interleaved to read or write to
+      multiple disks in parallel.  Also, due to the nature of
+      <acronym>RAID</acronym>3, the number of drives must be
+      equal to 3, 5, 9, 17, and so on, or 2^n + 1.</para>
+
+    <sect2>
+      <title>Creating a Dedicated <acronym>RAID</acronym>3
+	Array</title>
+
+      <para>In &os;, support for <acronym>RAID</acronym>3 is
+	implemented by the &man.graid3.8; <acronym>GEOM</acronym>
+	class.  Creating a dedicated
+	<acronym>RAID</acronym>3 array on &os; requires the following
+	steps.</para>
+
+      <note>
+	<para>While it is theoretically possible to boot from a
+	  <acronym>RAID</acronym>3 array on &os;, that configuration
+	  is uncommon and is not advised.</para>
+      </note>
+
+      <procedure>
+	<step>
+	  <para>First, load the <filename>geom_raid3.ko</filename>
+	    kernel module by issuing the following command:</para>
+
+	  <screen>&prompt.root; <userinput>graid3 load</userinput></screen>
+
+	  <para>Alternatively, it is possible to manually load the
+	    <filename>geom_raid3.ko</filename> module:</para>
+
+	  <screen>&prompt.root; <userinput>kldload geom_raid3.ko</userinput></screen>
+	</step>
+
+	<step>
+	  <para>Create or ensure that a suitable mount point
+	    exists:</para>
+
+	  <screen>&prompt.root; <userinput>mkdir <replaceable>/multimedia/</replaceable></userinput></screen>
+	</step>
+
+	<step>
+	  <para>Determine the device names for the disks which will be
+	    added to the array, and create the new
+	    <acronym>RAID</acronym>3 device.  The final device listed
+	    will act as the dedicated parity disk.  This
+	    example uses three unpartitioned
+	    <acronym>ATA</acronym> drives:
+	    <filename><replaceable>ada1</replaceable></filename>
+	    and
+	    <filename><replaceable>ada2</replaceable></filename>
+	    for data, and
+	    <filename><replaceable>ada3</replaceable></filename>
+	    for parity.</para>
+
+	  <screen>&prompt.root; <userinput>graid3 label -v gr0 /dev/ada1 /dev/ada2 /dev/ada3</userinput>
+Metadata value stored on /dev/ada1.
+Metadata value stored on /dev/ada2.
+Metadata value stored on /dev/ada3.
+Done.</screen>
+	</step>
+
+	<step>
+	  <para>Partition the newly created
+	    <filename>gr0</filename> device and put a UFS file
+	    system on it:</para>
+
+	  <screen>&prompt.root; <userinput>gpart create -s GPT /dev/raid3/gr0</userinput>
+&prompt.root; <userinput>gpart add -t freebsd-ufs /dev/raid3/gr0</userinput>
+&prompt.root; <userinput>newfs -j /dev/raid3/gr0p1</userinput></screen>
+
+	  <para>Many numbers will glide across the screen, and after a
+	    bit of time, the process will be complete.  The volume has
+	    been created and is ready to be mounted:</para>
+
+	  <screen>&prompt.root; <userinput>mount /dev/raid3/gr0p1 /multimedia/</userinput></screen>
+
+	  <para>The <acronym>RAID</acronym>3 array is now ready to
+	    use.</para>
+	</step>
+      </procedure>
+
+      <para>Additional configuration is needed to retain the above
+	setup across system reboots.</para>
+
+      <procedure>
+	<step>
+	  <para>The <filename>geom_raid3.ko</filename> module must be
+	    loaded before the array can be mounted.  To automatically
+	    load the kernel module during system initialization, add
+	    the following line to
+	    <filename>/boot/loader.conf</filename>:</para>
+
+	  <programlisting>geom_raid3_load="YES"</programlisting>
+	</step>
+
+	<step>
+	  <para>The following volume information must be added to
+	    <filename>/etc/fstab</filename> in order to
+	    automatically mount the array's file system during
+	    the system boot process:</para>
+
+	  <programlisting>/dev/raid3/gr0p1	/multimedia	ufs	rw	2	2</programlisting>
+	</step>
+      </procedure>
+    </sect2>
+  </sect1>
+
   <sect1 xml:id="geom-graid">
     <info>
       <title>Software <acronym>RAID</acronym> Devices</title>
@@ -1153,179 +1326,6 @@ raid/r0  OPTIMAL  ada0 (ACTIVE (ACTIVE))
     </sect2>
   </sect1>
 
-  <sect1 xml:id="geom-raid3">
-    <info>
-
-      <title><acronym>RAID</acronym>3 - Byte-level Striping with
-	Dedicated Parity</title>
-
-      <authorgroup>
-	<author>
-	  <personname>
-	    <firstname>Mark</firstname>
-	    <surname>Gladman</surname>
-	  </personname>
-	  <contrib>Written by </contrib>
-	</author>
-
-	<author>
-	  <personname>
-	    <firstname>Daniel</firstname>
-	    <surname>Gerzo</surname>
-	  </personname>
-	</author>
-      </authorgroup>
-
-      <authorgroup>
-	<author>
-	  <personname>
-	    <firstname>Tom</firstname>
-	    <surname>Rhodes</surname>
-	  </personname>
-	  <contrib>Based on documentation by </contrib>
-	</author>
-
-	<author>
-	  <personname>
-	    <firstname>Murray</firstname>
-	    <surname>Stokely</surname>
-	  </personname>
-	</author>
-      </authorgroup>
-    </info>
-
-    <indexterm>
-      <primary><acronym>GEOM</acronym></primary>
-    </indexterm>
-    <indexterm>
-      <primary>RAID3</primary>
-    </indexterm>
-
-    <para><acronym>RAID</acronym>3 is a method used to combine several
-      disk drives into a single volume with a dedicated parity disk.
-      In a <acronym>RAID</acronym>3 system, data is split up into a
-      number of bytes that are written across all the drives in the
-      array except for one disk which acts as a dedicated parity disk.
-      This means that reading 1024KB from a
-      <acronym>RAID</acronym>3 implementation will access all disks in
-      the array.  Performance can be enhanced by using multiple disk
-      controllers.  The <acronym>RAID</acronym>3 array provides a
-      fault tolerance of 1 drive, while providing a capacity of 1 -
-      1/n times the total capacity of all drives in the array, where n
-      is the number of hard drives in the array.  Such a configuration
-      is mostly suitable for storing data of larger sizes such as
-      multimedia files.</para>
-
-    <para>At least 3 physical hard drives are required to build a
-      <acronym>RAID</acronym>3 array.  Each disk must be of the same
-      size, since I/O requests are interleaved to read or write to
-      multiple disks in parallel.  Also, due to the nature of
-      <acronym>RAID</acronym>3, the number of drives must be
-      equal to 3, 5, 9, 17, and so on, or 2^n + 1.</para>
-
-    <sect2>
-      <title>Creating a Dedicated <acronym>RAID</acronym>3
-	Array</title>
-
-      <para>In &os;, support for <acronym>RAID</acronym>3 is
-	implemented by the &man.graid3.8; <acronym>GEOM</acronym>
-	class.  Creating a dedicated
-	<acronym>RAID</acronym>3 array on &os; requires the following
-	steps.</para>
-
-      <note>
-	<para>While it is theoretically possible to boot from a
-	  <acronym>RAID</acronym>3 array on &os;, that configuration
-	  is uncommon and is not advised.</para>
-      </note>
-
-      <procedure>
-	<step>
-	  <para>First, load the <filename>geom_raid3.ko</filename>
-	    kernel module by issuing the following command:</para>
-
-	  <screen>&prompt.root; <userinput>graid3 load</userinput></screen>
-
-	  <para>Alternatively, it is possible to manually load the
-	    <filename>geom_raid3.ko</filename> module:</para>
-
-	  <screen>&prompt.root; <userinput>kldload geom_raid3.ko</userinput></screen>
-	</step>
-
-	<step>
-	  <para>Create or ensure that a suitable mount point
-	    exists:</para>
-
-	  <screen>&prompt.root; <userinput>mkdir <replaceable>/multimedia/</replaceable></userinput></screen>
-	</step>
-
-	<step>
-	  <para>Determine the device names for the disks which will be
-	    added to the array, and create the new
-	    <acronym>RAID</acronym>3 device.  The final device listed
-	    will act as the dedicated parity disk.  This
-	    example uses three unpartitioned
-	    <acronym>ATA</acronym> drives:
-	    <filename><replaceable>ada1</replaceable></filename>
-	    and
-	    <filename><replaceable>ada2</replaceable></filename>
-	    for data, and
-	    <filename><replaceable>ada3</replaceable></filename>
-	    for parity.</para>
-
-	  <screen>&prompt.root; <userinput>graid3 label -v gr0 /dev/ada1 /dev/ada2 /dev/ada3</userinput>
-Metadata value stored on /dev/ada1.
-Metadata value stored on /dev/ada2.
-Metadata value stored on /dev/ada3.
-Done.</screen>
-	</step>
-
-	<step>
-	  <para>Partition the newly created
-	    <filename>gr0</filename> device and put a UFS file
-	    system on it:</para>
-
-	  <screen>&prompt.root; <userinput>gpart create -s GPT /dev/raid3/gr0</userinput>
-&prompt.root; <userinput>gpart add -t freebsd-ufs /dev/raid3/gr0</userinput>
-&prompt.root; <userinput>newfs -j /dev/raid3/gr0p1</userinput></screen>
-
-	  <para>Many numbers will glide across the screen, and after a
-	    bit of time, the process will be complete.  The volume has
-	    been created and is ready to be mounted:</para>
-
-	  <screen>&prompt.root; <userinput>mount /dev/raid3/gr0p1 /multimedia/</userinput></screen>
-
-	  <para>The <acronym>RAID</acronym>3 array is now ready to
-	    use.</para>
-	</step>
-      </procedure>
-
-      <para>Additional configuration is needed to retain the above
-	setup across system reboots.</para>
-
-      <procedure>
-	<step>
-	  <para>The <filename>geom_raid3.ko</filename> module must be
-	    loaded before the array can be mounted.  To automatically
-	    load the kernel module during system initialization, add
-	    the following line to
-	    <filename>/boot/loader.conf</filename>:</para>
-
-	  <programlisting>geom_raid3_load="YES"</programlisting>
-	</step>
-
-	<step>
-	  <para>The following volume information must be added to
-	    <filename>/etc/fstab</filename> in order to
-	    automatically mount the array's file system during
-	    the system boot process:</para>
-
-	  <programlisting>/dev/raid3/gr0p1	/multimedia	ufs	rw	2	2</programlisting>
-	</step>
-      </procedure>
-    </sect2>
-  </sect1>
-
   <sect1 xml:id="geom-ggate">
     <title><acronym>GEOM</acronym> Gate Network Devices</title>
 


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