Put RAID3 chapter before Software RAID Devices chapter.
Sponsored by: iXsystems
This commit is contained in:
Dru Lavigne
parent
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commit
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Notes:
svn2git
2020-12-08 03:00:23 +00:00
svn path=/head/; revision=44663
1 changed files with 173 additions and 173 deletions
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@ -842,6 +842,179 @@ mountroot></screen>
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</sect2>
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</sect1>
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<sect1 xml:id="geom-raid3">
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<info>
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<title><acronym>RAID</acronym>3 - Byte-level Striping with
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Dedicated Parity</title>
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<authorgroup>
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<author>
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<personname>
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<firstname>Mark</firstname>
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<surname>Gladman</surname>
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</personname>
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<contrib>Written by </contrib>
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</author>
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<author>
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<personname>
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<firstname>Daniel</firstname>
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<surname>Gerzo</surname>
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</personname>
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</author>
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</authorgroup>
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<authorgroup>
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<author>
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<personname>
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<firstname>Tom</firstname>
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<surname>Rhodes</surname>
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</personname>
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<contrib>Based on documentation by </contrib>
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</author>
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<author>
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<personname>
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<firstname>Murray</firstname>
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<surname>Stokely</surname>
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</personname>
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</author>
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</authorgroup>
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</info>
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<indexterm>
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<primary><acronym>GEOM</acronym></primary>
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</indexterm>
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<indexterm>
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<primary>RAID3</primary>
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</indexterm>
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<para><acronym>RAID</acronym>3 is a method used to combine several
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disk drives into a single volume with a dedicated parity disk.
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In a <acronym>RAID</acronym>3 system, data is split up into a
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number of bytes that are written across all the drives in the
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array except for one disk which acts as a dedicated parity disk.
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This means that reading 1024KB from a
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<acronym>RAID</acronym>3 implementation will access all disks in
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the array. Performance can be enhanced by using multiple disk
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controllers. The <acronym>RAID</acronym>3 array provides a
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fault tolerance of 1 drive, while providing a capacity of 1 -
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1/n times the total capacity of all drives in the array, where n
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is the number of hard drives in the array. Such a configuration
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is mostly suitable for storing data of larger sizes such as
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multimedia files.</para>
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<para>At least 3 physical hard drives are required to build a
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<acronym>RAID</acronym>3 array. Each disk must be of the same
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size, since I/O requests are interleaved to read or write to
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multiple disks in parallel. Also, due to the nature of
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<acronym>RAID</acronym>3, the number of drives must be
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equal to 3, 5, 9, 17, and so on, or 2^n + 1.</para>
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<sect2>
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<title>Creating a Dedicated <acronym>RAID</acronym>3
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Array</title>
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<para>In &os;, support for <acronym>RAID</acronym>3 is
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implemented by the &man.graid3.8; <acronym>GEOM</acronym>
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class. Creating a dedicated
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<acronym>RAID</acronym>3 array on &os; requires the following
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steps.</para>
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<note>
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<para>While it is theoretically possible to boot from a
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<acronym>RAID</acronym>3 array on &os;, that configuration
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is uncommon and is not advised.</para>
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</note>
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<procedure>
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<step>
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<para>First, load the <filename>geom_raid3.ko</filename>
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kernel module by issuing the following command:</para>
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<screen>&prompt.root; <userinput>graid3 load</userinput></screen>
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<para>Alternatively, it is possible to manually load the
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<filename>geom_raid3.ko</filename> module:</para>
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<screen>&prompt.root; <userinput>kldload geom_raid3.ko</userinput></screen>
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</step>
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<step>
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<para>Create or ensure that a suitable mount point
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exists:</para>
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<screen>&prompt.root; <userinput>mkdir <replaceable>/multimedia/</replaceable></userinput></screen>
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</step>
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<step>
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<para>Determine the device names for the disks which will be
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added to the array, and create the new
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<acronym>RAID</acronym>3 device. The final device listed
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will act as the dedicated parity disk. This
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example uses three unpartitioned
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<acronym>ATA</acronym> drives:
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<filename><replaceable>ada1</replaceable></filename>
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and
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<filename><replaceable>ada2</replaceable></filename>
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for data, and
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<filename><replaceable>ada3</replaceable></filename>
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for parity.</para>
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<screen>&prompt.root; <userinput>graid3 label -v gr0 /dev/ada1 /dev/ada2 /dev/ada3</userinput>
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Metadata value stored on /dev/ada1.
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Metadata value stored on /dev/ada2.
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Metadata value stored on /dev/ada3.
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Done.</screen>
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</step>
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<step>
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<para>Partition the newly created
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<filename>gr0</filename> device and put a UFS file
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system on it:</para>
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<screen>&prompt.root; <userinput>gpart create -s GPT /dev/raid3/gr0</userinput>
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&prompt.root; <userinput>gpart add -t freebsd-ufs /dev/raid3/gr0</userinput>
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&prompt.root; <userinput>newfs -j /dev/raid3/gr0p1</userinput></screen>
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<para>Many numbers will glide across the screen, and after a
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bit of time, the process will be complete. The volume has
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been created and is ready to be mounted:</para>
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<screen>&prompt.root; <userinput>mount /dev/raid3/gr0p1 /multimedia/</userinput></screen>
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<para>The <acronym>RAID</acronym>3 array is now ready to
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use.</para>
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</step>
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</procedure>
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<para>Additional configuration is needed to retain the above
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setup across system reboots.</para>
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<procedure>
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<step>
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<para>The <filename>geom_raid3.ko</filename> module must be
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loaded before the array can be mounted. To automatically
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load the kernel module during system initialization, add
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the following line to
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<filename>/boot/loader.conf</filename>:</para>
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<programlisting>geom_raid3_load="YES"</programlisting>
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</step>
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<step>
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<para>The following volume information must be added to
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<filename>/etc/fstab</filename> in order to
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automatically mount the array's file system during
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the system boot process:</para>
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<programlisting>/dev/raid3/gr0p1 /multimedia ufs rw 2 2</programlisting>
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</step>
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</procedure>
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</sect2>
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</sect1>
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<sect1 xml:id="geom-graid">
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<info>
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<title>Software <acronym>RAID</acronym> Devices</title>
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@ -1153,179 +1326,6 @@ raid/r0 OPTIMAL ada0 (ACTIVE (ACTIVE))
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</sect2>
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</sect1>
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<sect1 xml:id="geom-raid3">
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<info>
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<title><acronym>RAID</acronym>3 - Byte-level Striping with
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Dedicated Parity</title>
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<authorgroup>
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<author>
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<personname>
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<firstname>Mark</firstname>
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<surname>Gladman</surname>
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</personname>
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<contrib>Written by </contrib>
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</author>
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<author>
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<personname>
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<firstname>Daniel</firstname>
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<surname>Gerzo</surname>
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</personname>
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</author>
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</authorgroup>
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<authorgroup>
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<author>
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<personname>
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<firstname>Tom</firstname>
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<surname>Rhodes</surname>
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</personname>
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<contrib>Based on documentation by </contrib>
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</author>
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<author>
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<personname>
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<firstname>Murray</firstname>
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<surname>Stokely</surname>
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</personname>
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</author>
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</authorgroup>
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</info>
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<indexterm>
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<primary><acronym>GEOM</acronym></primary>
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</indexterm>
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<indexterm>
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<primary>RAID3</primary>
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</indexterm>
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<para><acronym>RAID</acronym>3 is a method used to combine several
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disk drives into a single volume with a dedicated parity disk.
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In a <acronym>RAID</acronym>3 system, data is split up into a
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number of bytes that are written across all the drives in the
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array except for one disk which acts as a dedicated parity disk.
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This means that reading 1024KB from a
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<acronym>RAID</acronym>3 implementation will access all disks in
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the array. Performance can be enhanced by using multiple disk
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controllers. The <acronym>RAID</acronym>3 array provides a
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fault tolerance of 1 drive, while providing a capacity of 1 -
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1/n times the total capacity of all drives in the array, where n
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is the number of hard drives in the array. Such a configuration
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is mostly suitable for storing data of larger sizes such as
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multimedia files.</para>
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<para>At least 3 physical hard drives are required to build a
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<acronym>RAID</acronym>3 array. Each disk must be of the same
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size, since I/O requests are interleaved to read or write to
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multiple disks in parallel. Also, due to the nature of
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<acronym>RAID</acronym>3, the number of drives must be
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equal to 3, 5, 9, 17, and so on, or 2^n + 1.</para>
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<sect2>
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<title>Creating a Dedicated <acronym>RAID</acronym>3
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Array</title>
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<para>In &os;, support for <acronym>RAID</acronym>3 is
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implemented by the &man.graid3.8; <acronym>GEOM</acronym>
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class. Creating a dedicated
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<acronym>RAID</acronym>3 array on &os; requires the following
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steps.</para>
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<note>
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<para>While it is theoretically possible to boot from a
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<acronym>RAID</acronym>3 array on &os;, that configuration
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is uncommon and is not advised.</para>
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</note>
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<procedure>
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<step>
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<para>First, load the <filename>geom_raid3.ko</filename>
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kernel module by issuing the following command:</para>
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<screen>&prompt.root; <userinput>graid3 load</userinput></screen>
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<para>Alternatively, it is possible to manually load the
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<filename>geom_raid3.ko</filename> module:</para>
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<screen>&prompt.root; <userinput>kldload geom_raid3.ko</userinput></screen>
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</step>
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<step>
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<para>Create or ensure that a suitable mount point
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exists:</para>
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<screen>&prompt.root; <userinput>mkdir <replaceable>/multimedia/</replaceable></userinput></screen>
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</step>
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<step>
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<para>Determine the device names for the disks which will be
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added to the array, and create the new
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<acronym>RAID</acronym>3 device. The final device listed
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will act as the dedicated parity disk. This
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example uses three unpartitioned
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<acronym>ATA</acronym> drives:
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<filename><replaceable>ada1</replaceable></filename>
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and
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<filename><replaceable>ada2</replaceable></filename>
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for data, and
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<filename><replaceable>ada3</replaceable></filename>
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for parity.</para>
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<screen>&prompt.root; <userinput>graid3 label -v gr0 /dev/ada1 /dev/ada2 /dev/ada3</userinput>
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Metadata value stored on /dev/ada1.
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Metadata value stored on /dev/ada2.
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Metadata value stored on /dev/ada3.
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Done.</screen>
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</step>
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<step>
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<para>Partition the newly created
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<filename>gr0</filename> device and put a UFS file
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system on it:</para>
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<screen>&prompt.root; <userinput>gpart create -s GPT /dev/raid3/gr0</userinput>
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&prompt.root; <userinput>gpart add -t freebsd-ufs /dev/raid3/gr0</userinput>
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&prompt.root; <userinput>newfs -j /dev/raid3/gr0p1</userinput></screen>
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<para>Many numbers will glide across the screen, and after a
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bit of time, the process will be complete. The volume has
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been created and is ready to be mounted:</para>
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<screen>&prompt.root; <userinput>mount /dev/raid3/gr0p1 /multimedia/</userinput></screen>
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<para>The <acronym>RAID</acronym>3 array is now ready to
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use.</para>
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</step>
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</procedure>
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<para>Additional configuration is needed to retain the above
|
||||
setup across system reboots.</para>
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||||
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<procedure>
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||||
<step>
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<para>The <filename>geom_raid3.ko</filename> module must be
|
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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>
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</step>
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|
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<step>
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<para>The following volume information must be added to
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<filename>/etc/fstab</filename> in order to
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automatically mount the array's file system during
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the system boot process:</para>
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||||
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<programlisting>/dev/raid3/gr0p1 /multimedia ufs rw 2 2</programlisting>
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</step>
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</procedure>
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</sect2>
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</sect1>
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<sect1 xml:id="geom-ggate">
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<title><acronym>GEOM</acronym> Gate Network Devices</title>
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