svn commit: r44531 - head/en_US.ISO8859-1/books/handbook/geom
Dru Lavigne
dru at FreeBSD.org
Fri Apr 11 15:47:39 UTC 2014
Author: dru
Date: Fri Apr 11 15:47:38 2014
New Revision: 44531
URL: http://svnweb.freebsd.org/changeset/doc/44531
Log:
Editorial review of Synopsis/Introduction and RAID0 sections.
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 11 14:00:48 2014 (r44530)
+++ head/en_US.ISO8859-1/books/handbook/geom/chapter.xml Fri Apr 11 15:47:38 2014 (r44531)
@@ -26,31 +26,34 @@
<title>Synopsis</title>
<indexterm>
- <primary>GEOM</primary>
+ <primary><acronym>GEOM</acronym></primary>
</indexterm>
<indexterm>
- <primary>GEOM Disk Framework</primary>
- <see>GEOM</see>
+ <primary><acronym>GEOM</acronym> Disk Framework</primary>
+ <see><acronym>GEOM</acronym></see>
</indexterm>
- <para>This chapter covers the use of disks under the GEOM
- framework in &os;. This includes the major <acronym
- role="Redundant Array of Inexpensive Disks">RAID</acronym>
+ <para>In &os;, the <acronym>GEOM</acronym> framework permits access and control to classes, such as Master
+ Boot Records and <acronym>BSD</acronym> labels, through the use
+ of providers, or the disk devices in <filename>/dev</filename>.
+ By supporting various software <acronym>RAID</acronym>
+ configurations, <acronym>GEOM</acronym> transparently provides access to the
+ operating system and operating system utilities.</para>
+
+ <para>This chapter covers the use of disks under the <acronym>GEOM</acronym>
+ framework in &os;. This includes the major <acronym>RAID</acronym>
control utilities which use the framework for configuration.
- This chapter will not go into in depth discussion on how GEOM
- handles or controls I/O, the underlying subsystem, or code.
- This information is provided in &man.geom.4; and its various
- <literal>SEE ALSO</literal> references. This chapter is also
+ This chapter is
not a definitive guide to <acronym>RAID</acronym> configurations
- and only GEOM-supported <acronym>RAID</acronym> classifications
- will be discussed.</para>
+ and only <acronym>GEOM</acronym>-supported <acronym>RAID</acronym> classifications
+ are discussed.</para>
<para>After reading this chapter, you will know:</para>
<itemizedlist>
<listitem>
<para>What type of <acronym>RAID</acronym> support is
- available through GEOM.</para>
+ available through <acronym>GEOM</acronym>.</para>
</listitem>
<listitem>
@@ -61,11 +64,11 @@
<listitem>
<para>How to mirror, stripe, encrypt, and remotely connect
- disk devices through GEOM.</para>
+ disk devices through <acronym>GEOM</acronym>.</para>
</listitem>
<listitem>
- <para>How to troubleshoot disks attached to the GEOM
+ <para>How to troubleshoot disks attached to the <acronym>GEOM</acronym>
framework.</para>
</listitem>
</itemizedlist>
@@ -74,28 +77,17 @@
<itemizedlist>
<listitem>
- <para>Understand how &os; treats <link linkend="disks">disk
- devices</link>.</para>
+ <para>Understand how &os; treats disk devices (<xref
+ linkend="disks"/>).</para>
</listitem>
<listitem>
- <para>Know how to configure and install a new
- <link linkend="kernelconfig">&os; kernel</link>.</para>
+ <para>Know how to configure and install a new kernel
+ (<xref linkend="kernelconfig"/>.</para>
</listitem>
</itemizedlist>
</sect1>
- <sect1 xml:id="geom-intro">
- <title>GEOM Introduction</title>
-
- <para>GEOM permits access and control to classes, such as Master
- Boot Records and <acronym>BSD</acronym> labels, through the use
- of providers, or the special files in <filename>/dev</filename>.
- By supporting various software <acronym>RAID</acronym>
- configurations, GEOM transparently provides access to the
- operating system and operating system utilities.</para>
- </sect1>
-
<sect1 xml:id="geom-striping">
<info>
<title>RAID0 - Striping</title>
@@ -119,30 +111,29 @@
</info>
<indexterm>
- <primary>GEOM</primary>
+ <primary><acronym>GEOM</acronym></primary>
</indexterm>
<indexterm>
<primary>Striping</primary>
</indexterm>
- <para>Striping combine several disk drives into a single volume.
- In many cases, this is done through the use of hardware
- controllers. The GEOM disk subsystem provides software support
- for <acronym>RAID</acronym>0, also known as disk
- striping.</para>
-
- <para>In a <acronym>RAID</acronym>0 system, data is split into
- blocks that get written across all the drives in the array.
- Instead of having to wait on the system to write 256k to one
- disk, a <acronym>RAID</acronym>0 system can simultaneously write
- 64k to each of four different disks, offering superior I/O
+ <para>Striping combines several disk drives into a single volume.
+ Striping can be performed through the use of hardware
+ <acronym>RAID</acronym> controllers. The
+ <acronym>GEOM</acronym> disk subsystem provides software support
+ for disk striping, also known as <acronym>RAID0</acronym>,
+ without the need for a <acronym>RAID</acronym> disk
+ controller.</para>
+
+ <para>In <acronym>RAID0</acronym>, data is split into
+ blocks that are written across all the drives in the array. As
+ seen in the following illustration,
+ instead of having to wait on the system to write 256k to one
+ disk, <acronym>RAID0</acronym> can simultaneously write
+ 64k to each of the four disks in the array, offering superior <acronym>I/O</acronym>
performance. This performance can be enhanced further by using
multiple disk controllers.</para>
-
- <para>Each disk in a <acronym>RAID</acronym>0 stripe must be of
- the same size, since I/O requests are interleaved to read or
- write to multiple disks in parallel.</para>
-
+
<mediaobject>
<imageobject>
<imagedata fileref="geom/striping" align="center"/>
@@ -153,8 +144,26 @@
</textobject>
</mediaobject>
+ <para>Each disk in a <acronym>RAID0</acronym> stripe must be of
+ the same size, since <acronym>I/O</acronym> requests are interleaved to read or
+ write to multiple disks in parallel.</para>
+
+ <note>
+ <para><acronym>RAID0</acronym> does <emphasis>not</emphasis>
+ provide any redundancy. This means that if one disk in the
+ array fails, all of the data on the disks is lost. If the
+ data is important, implement a backup strategy that regularly
+ saves backups to a remote system or device.</para>
+ </note>
+
+ <para>The process for creating a software,
+ <acronym>GEOM</acronym>-based <acronym>RAID0</acronym> on a &os;
+ system using commodity disks is as follows. Once the stripe is
+ created, refer to &man.gstripe..8; for more information on how
+ to control an existing stripe.</para>
+
<procedure>
- <title>Creating a Stripe of Unformatted ATA Disks</title>
+ <title>Creating a Stripe of Unformatted <acronym>ATA</acronym> Disks</title>
<step>
<para>Load the <filename>geom_stripe.ko</filename>
@@ -167,9 +176,7 @@
<para>Ensure that a suitable mount point exists. If this
volume will become a root partition, then temporarily use
another mount point such as
- <filename>/mnt</filename>:</para>
-
- <screen>&prompt.root; <userinput>mkdir /mnt</userinput></screen>
+ <filename>/mnt</filename>.</para>
</step>
<step>
@@ -199,8 +206,8 @@ Done.</screen>
<filename>/dev/stripe</filename> in
addition to <filename>st0</filename>. Those include
<filename>st0a</filename> and
- <filename>st0c</filename>. At this point, a file system
- may be created on <filename>st0a</filename> using
+ <filename>st0c</filename>. At this point, a <acronym>UFS</acronym> file system
+ can be created on <filename>st0a</filename> using
<command>newfs</command>:</para>
<screen>&prompt.root; <userinput>newfs -U /dev/stripe/st0a</userinput></screen>
@@ -209,12 +216,14 @@ Done.</screen>
few seconds, the process will be complete. The volume has
been created and is ready to be mounted.</para>
</step>
- </procedure>
+ <step>
<para>To manually mount the created disk stripe:</para>
<screen>&prompt.root; <userinput>mount /dev/stripe/st0a /mnt</userinput></screen>
+ </step>
+ <step>
<para>To mount this striped file system automatically during the
boot process, place the volume information in
<filename>/etc/fstab</filename>. In this example, a permanent
@@ -224,19 +233,23 @@ Done.</screen>
<screen>&prompt.root; <userinput>mkdir /stripe</userinput>
&prompt.root; <userinput>echo "/dev/stripe/st0a /stripe ufs rw 2 2" \</userinput>
<userinput>>> /etc/fstab</userinput></screen>
+ </step>
+ <step>
<para>The <filename>geom_stripe.ko</filename> module must also be
automatically loaded during system initialization, by adding a
line to <filename>/boot/loader.conf</filename>:</para>
<screen>&prompt.root; <userinput>echo 'geom_stripe_load="YES"' >> /boot/loader.conf</userinput></screen>
+ </step>
+ </procedure>
</sect1>
<sect1 xml:id="geom-mirror">
<title>RAID1 - Mirroring</title>
<indexterm>
- <primary>GEOM</primary>
+ <primary><acronym>GEOM</acronym></primary>
</indexterm>
<indexterm>
<primary>Disk Mirroring</primary>
@@ -856,7 +869,7 @@ mountroot></screen>
</info>
<indexterm>
- <primary>GEOM</primary>
+ <primary><acronym>GEOM</acronym></primary>
</indexterm>
<indexterm>
<primary>Software RAID Devices</primary>
@@ -1193,7 +1206,7 @@ raid/r0 OPTIMAL ada0 (ACTIVE (ACTIVE))
</info>
<indexterm>
- <primary>GEOM</primary>
+ <primary><acronym>GEOM</acronym></primary>
</indexterm>
<indexterm>
<primary>RAID3</primary>
@@ -1325,9 +1338,9 @@ Done.</screen>
</sect1>
<sect1 xml:id="geom-ggate">
- <title>GEOM Gate Network Devices</title>
+ <title><acronym>GEOM</acronym> Gate Network Devices</title>
- <para>GEOM supports the remote use of devices, such as disks,
+ <para><acronym>GEOM</acronym> supports the remote use of devices, such as disks,
CD-ROMs, and files through the use of the gate utilities.
This is similar to <acronym>NFS</acronym>.</para>
@@ -1373,7 +1386,7 @@ ggate0
<title>Labeling Disk Devices</title>
<indexterm>
- <primary>GEOM</primary>
+ <primary><acronym>GEOM</acronym></primary>
</indexterm>
<indexterm>
<primary>Disk Labels</primary>
@@ -1579,10 +1592,10 @@ ufsid/486b6fc16926168e N/A ad4s1f</
</sect1>
<sect1 xml:id="geom-gjournal">
- <title>UFS Journaling Through GEOM</title>
+ <title>UFS Journaling Through <acronym>GEOM</acronym></title>
<indexterm>
- <primary>GEOM</primary>
+ <primary><acronym>GEOM</acronym></primary>
</indexterm>
<indexterm>
<primary>Journaling</primary>
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