doc/en/lvm2.xml

<?xml version='1.0' encoding="UTF-8"?>
<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/lvm2.xml,v 1.10 2005/02/13 14:01:22 aaby Exp $ -->
<!DOCTYPE guide SYSTEM "/dtd/guide.dtd">

<guide link = "/doc/en/lvm2.xml">
<title>Gentoo LVM2 installation</title>
<author title="Author">
  <mail link="avi@CFFtechnologies.com">Avi Schwartz</mail>
</author>
<author title="Contributor">
  <mail link="rajiv@gentoo.org">Rajiv Manglani</mail>
</author>
<author title="Editor">
  <mail link="neysx@gentoo.org">Xavier Neys</mail>
</author>

<abstract>
This guide describes how to setup your Gentoo machine using the Logical Volume
Manager version 2 (LVM2).
</abstract>

<license/>

<version>2.0.7</version>
<date>2005-04-07</date>

<chapter>
<title>Introduction</title>
<section>
<body>

<p>
This guide is based on an example with two IDE hard disks.  It means that you
will more than likely need to change the drive, partition names and partition
sizes to match your own setup and needs.
</p>

<warn>
This document is not intended to be an LVM2 tutorial.  It serves as a
supplement to the Gentoo installation procedure as described in the <uri
link="/doc/en/handbook/handbook-x86.xml?part=1&amp;chap=0">Handbook, Part 
1</uri>. Make sure you <c>read</c> the Gentoo Installation Manual 
<c>before</c> you start your installation process.
</warn>

<note>
For a complete LVM HOWTO point your browser to
<uri>http://tldp.org/HOWTO/LVM-HOWTO</uri>
</note>

</body>
</section>
<section>
<title>Initial requirements</title>
<body>

<p>
If you do a fresh install of Gentoo, you will need to use a bootable CD with
LVM2 support such as a Gentoo LiveCD. You can find the LiveCD for an x86
architecture on our <uri
link="http://www.gentoo.org/main/en/mirrors.xml">mirrors</uri> under
<path>/releases/x86/2004.3/livecd</path>. Other architectures might
be supported as well.
</p>

<p>
If you install LVM2 on a currently running system with some spare hard disk
space, you will need to enable the LVM2 module (<path>dm-mod</path>). This
module is available in <path>gentoo-sources</path>, in
<path>development-sources</path> and in <path>gentoo-dev-sources</path>.
Compiling your kernel and getting LVM2 to work is covered later in this guide.
</p>

<p>
Not all 2.4 kernels provided by Gentoo support LVM2!
</p>

<warn>
The LVM2 available on the 2005.0 installation CDs is erroneously linked
dynamically against a library (libgpm) which resides in /usr. This means you 
cannot have your /usr in an LVM environment as well. Either install the latest
version or version 2.0.33 (not -r1) which are built statically.
</warn>

</body>
</section>
<section>
<title>Partitions</title>
<body>

<p>
Our example system has two IDE hard disks and will be partitioned as follows:
</p>

<ul>
  <li>/dev/hda1  --  /boot</li>
  <li>/dev/hda2  --  (swap)</li>
  <li>/dev/hda3  --  /</li>
  <li>/dev/hda4  --  Will be used by LVM2</li>
  <li>/dev/hdb1  --  Will be used by LVM2</li>
</ul>

<impo>
Pay attention to the partition names as it is easy to confuse the a's and b's,
and the partition numbers. One false move could wipe out the wrong partition.
You have been warned!
</impo>

<p>
OK, time to start...
</p>

</body>
</section>
</chapter>

<chapter>
<title>Installation</title>
<section>
<body>

<p>
Follow the handbook, but with the following amendments to chapter <c>4. 
Preparing the Disks</c>:
</p>

<p>
Use <c>fdisk</c> as described in the handbook, but use the partition scheme
mentioned above as an example. It is only <e>an example</e>, adapt it to your
own needs.
</p>

<p>
Create a small physical /boot partition (hda1). In this example, /boot will be
not managed by LVM2. This partition will contain your bootloader and your
kernel(s).  A 64MB partition should be well enough for quite a few kernel
generations.
</p>

<p>
Create a swap partition (hda2) and activate it.
</p>

<pre caption="Activating the swap partition">
# <i>mkswap /dev/hda2</i>
# <i>swapon /dev/hda2</i>
</pre>

<p>
Create a / (root) partition (hda3).  If you are interested in trying to put
your root partition under LVM management (which we do not recommend), see the
resources section at the end of this guide for a link to a mini-howto on how to
do this. The size of the root partition need  not be large if you will keep
<path>/opt /usr /home /var</path> and <path>/tmp</path> in an LVM2 Volume Group
(vg). In this case, 150M is sufficient.
</p>

<note>
It is <b>not</b> recommended to put the following directories in an 
LVM2 partition: <path>/etc</path>, <path>/lib</path>, <path>/mnt</path>, 
<path>/proc</path>, <path>/sbin</path>, <path>/dev</path>, and <path>/root</path>.
This way, you would still be able to log into your system (crippled, but 
still somewhat usable, as root) if something goes terribly wrong.
</note>

<p>
Assuming the /boot, swap and root partitions do not use the whole physical disk,
create a fourth partition on this disk and set it to type 8e (Linux LVM).
If you have more physical drives you would like to use with LVM, create 
one partition on each and give them the same type (8e).
</p>

<note>
Considering the huge size of current disks, you might consider splitting your
hard disks into smaller partitions instead of creating a big partition that
will be added to an LVM2 volume group in one block. LVM2 makes it easy to
extend your volumes after all. This leaves you some unallocated partitions you
might need to use outside of an LVM2 group. In short, don't use your disk space
until you know you need it. As an example, one contributor had split his
160&nbsp;Gb hard disk into 8 partitions of 20&nbsp;Gb each.
</note>

<p>
Load the LVM2 <path>dm-mod</path> module.
</p>

<pre caption="Loading the LVM2 module">
# <i>modprobe dm-mod</i>
</pre>

<p>
Scan and activate LVM:
</p>

<pre caption="Activating LVM">
<comment>(Avoid scanning your cdrom)</comment>
# <i>mkdir -p /etc/lvm</i>
# <i>echo 'devices { filter=["r/cdrom/"] }' >/etc/lvm/lvm.conf</i>
# <i>vgscan</i>
  Reading all physical volumes.  This may take a while...
  No volume groups found
<comment>(Make any previously set up volume groups available)</comment>
# <i>vgchange -a y</i>
</pre>

<p>
Prepare the partitions.
</p>

<pre caption="Preparing the partitions">
# <i>pvcreate /dev/hda4 /dev/hdb1</i>
  No physical volume label read from /dev/hda4
  Physical volume "/dev/hda4" successfully created
  No physical volume label read from /dev/hdb1
  Physical volume "/dev/hdb1" successfully created
</pre>

<p>
Setup a volume group. A volume group is the result of combining several
physical units into a single logical device.
</p>

<p>
In our example, <path>/dev/hda1</path>, <path>/dev/hda2</path> and
<path>/dev/hda3</path> are the <path>/boot</path>, swap and root partitions so
we need to combine <path>/dev/hda4</path> and <path>/dev/hdb1</path>. It can be
done with a single command, but, as an example, we will create our volume group
and extend it.
</p>

<pre caption="Creating and extending a volume group">
<comment>(Create a volume group named vg)</comment>
# <i>vgcreate vg /dev/hda4</i>
  /etc/lvm/backup: fsync failed: Invalid argument <comment>(Ignore this warning)</comment>
  Volume group "vg" successfully created
<comment>(Extending an existing volume group)</comment>
# <i>vgextend vg /dev/hdb1</i>
  /etc/lvm/backup: fsync failed: Invalid argument <comment>(Ignore this warning, again and later as well)</comment>
  Volume group "vg" successfully extended
</pre>

<p>
Create the logical volumes.  Logical volumes are the equivalent of partitions
you would create using fdisk in a non LVM2 environment. In our example, we
create the following partitions:
</p>

<table>
<tr>
  <th>Directory</th>
  <th>Size</th>
</tr>
<tr>
  <ti>/usr</ti>
  <ti>10 GB</ti>
</tr>
<tr>
  <ti>/home</ti>
  <ti>5 GB</ti>
</tr>
<tr>
  <ti>/opt</ti>
  <ti>5 GB</ti>
</tr>
<tr>
  <ti>/var</ti>
  <ti>10 GB</ti>
</tr>
<tr>
  <ti>/tmp</ti>
  <ti>2 GB</ti>
</tr>
</table>

<p>
Since we are going to use LVM2, we should not worry too much about partition
sizes because they can always be expanded as needed.
</p>

<note>
As Terje Kvernes commented, it is easier to increase the size of a partition
then to shrink it.  You might therefore want to start with smaller partitions
and increase their size as needed.
</note>

<pre caption="Creating and extending logical volumes">
# <i>lvcreate -L10G -nusr  vg</i>
  Logical volume "usr" created <comment>(Further similar messages not displayed)</comment>
# <i>lvcreate -L5G  -nhome vg</i>
# <i>lvcreate -L5G  -nopt  vg</i>
# <i>lvcreate -L10G -nvar  vg</i>
# <i>lvcreate -L2G  -ntmp  vg</i>
<comment>(As an example, let's extend a logical volume with 5 extra Gbytes)</comment>
# <i>lvextend -L+5G /dev/vg/home</i>
</pre>

<p>
Create filesystems on the logical volumes the same way you would on a regular
partition.  We use ext3 on the logical volumes but any filesystem of your
choice will work:
</p>

<pre caption="Creating the filesystems">
# <i>mke2fs -j /dev/vg/usr</i>
# <i>mke2fs -j /dev/vg/home</i>
# <i>mke2fs -j /dev/vg/opt</i>
# <i>mke2fs -j /dev/vg/var</i>
# <i>mke2fs -j /dev/vg/tmp</i>
</pre>

<p>
Mount your partitions as described in the handbook and mount your LVM2 logical
volumes as if they were partitions. Replace the usual <path>/dev/hdxx</path>
with <path>/dev/vg/logical_volumename</path>.
</p>

<pre caption="Mounting your logical volumes">
<comment>(Make sure you have mounted your root partition as described in the handbook first)</comment>
# <i>mkdir /mnt/gentoo/usr</i>
# <i>mount /dev/vg/usr /mnt/gentoo/usr</i>
# <i>mkdir /mnt/gentoo/home</i>
# <i>mount /dev/vg/home /mnt/gentoo/home</i>
# <i>mkdir /mnt/gentoo/opt</i>
# <i>mount /dev/vg/opt /mnt/gentoo/opt</i>
# <i>mkdir /mnt/gentoo/var</i>
# <i>mount /dev/vg/var /mnt/gentoo/var</i>
# <i>mkdir /mnt/gentoo/tmp</i>
# <i>mount /dev/vg/tmp /mnt/gentoo/tmp</i>
</pre>

<note>
The rest of the installation handbook is mostly unchanged so we shall not
walk you through it again except to point out differences.
</note>

<p>
When configuring your kernel, make sure to configure your kernel to
support LVM2 (not all 2.4 kernels do). Select the LVM2 module as follows:
</p>

<pre caption="Selecting the LVM2 module in a 2.4.x kernel">
Multi-device support (RAID and LVM)  ---&gt;
  [*] Multiple devices driver support (RAID and LVM)
  &lt; &gt;  RAID support
<comment>(Note that LVM is not selected on purpose, this was for LVM1)</comment>
  &lt; &gt;  Logical volume manager (LVM) support
  &lt;M&gt;  Device-mapper support
  &lt; &gt;   Mirror (RAID-1) support
</pre>

<pre caption="Selecting the LVM2 module in a 2.6.x kernel">
Device Drivers  ---&gt;
 Multi-device support (RAID and LVM)  ---&gt;
   [*] Multiple devices driver support (RAID and LVM)
   &lt; &gt;   RAID support
   &lt;M&gt;   Device mapper support
</pre>

<p>
The compiled module is called <path>dm-mod.ko</path>
</p>

<p>
After you have built your kernel and installed its modules, add the following
line to your <path>/etc/modules.autoload.d/kernel-{KV}</path> where {KV}
represents your kernel version (2.4 or 2.6) so that the LVM2 module gets loaded
when your machine is booted:
</p>

<pre caption="Adding the LVM2 module into /etc/modules.autoload.d/kernel-2.6">
# <i>nano -w /etc/modules.autoload.d/kernel-2.6</i>
<comment>(Add the following line)</comment>
dm-mod
</pre>

<p>
Now, install the lvm2 package.
</p>

<impo>
Make sure your <path>/usr/src/linux</path> link points to the kernel sources you
are using because the lvm2 ebuild depends on the device-mapper ebuild which
will check the presence of a required source file under
<path>/usr/src/linux/include/linux</path>.
</impo>

<pre caption="Emerging the LVM2 package">
# <i>emerge lvm2</i>
<comment>(At the time of writing, the stable version is 2.00.08.
With version 2.00.08, prevent lvm2 from probing your cdrom by doing:</comment>
# <i>echo 'devices { filter=["r/cdrom/"] }' >> /etc/lvm/lvm.conf</i>

<comment>(Versions 2.00.15 and later come with a /etc/lvm/lvm.conf
Edit your /etc/lvm/lvm.conf and follow the comments</comment>
# <i>nano -w /etc/lvm/lvm.conf</i>
</pre>

<p>
When editing your <path>/etc/fstab</path> file, follow the handbook and add
your LVM2 logical volumes as needed.  Again, here are a few lines needed for
our example:
</p>

<pre caption="Extract of /etc/fstab">
/dev/hda1     /boot   ext3    noauto,noatime 1 1
/dev/hda2     none    swap    sw             0 0
/dev/hda3     /       ext3    noatime        0 0
# Logical volumes
/dev/vg/usr   /usr    ext3    noatime        0 0
/dev/vg/home  /home   ext3    noatime        0 0
/dev/vg/opt   /opt    ext3    noatime        0 0
/dev/vg/var   /var    ext3    noatime        0 0
/dev/vg/tmp   /tmp    ext3    noatime        0 0
</pre>

<p>
When you reach the end of the installation part of the handbook, don't forget
to umount all your LVM2 logical volumes as well and for a good measure run the
following command before you reboot:
</p>

<pre caption="Shutting down LVM2">
# <i>vgchange -a n</i>
</pre>

<p>
Restart your machine and all partitions should be visible and mounted.
</p>

</body>
</section>
</chapter>

<chapter>
<title>Resources</title>
<section>
<body>

<ul>
  <li>
    The official <uri link="http://sources.redhat.com/lvm2">LVM2 home page</uri>
  </li>
  <li>
    The <uri link="http://tldp.org/HOWTO/LVM-HOWTO">LVM Howto</uri>
  </li>
  <li>
    Daniel Robbins's articles on LVM at IBM's DeveloperWorks:
    <uri>http://www-106.ibm.com/developerworks/linux/library/l-lvm/?dwzone=linux</uri>
    and 
    <uri>http://www-106.ibm.com/developerworks/linux/library/l-lvm2.html?dwzone=linux</uri>
  </li>
  <li>
    How to boot your root FS off of LVM1:
    <uri>http://www.the-infinite.org/archive/docs/lvm/howto-boot-off-root-lv.txt</uri>
  </li>
</ul>

</body>
</section>
</chapter>

<chapter>
<title>Acknowledgements</title>
<section>
<body>

<p>
Thanks <mail link="bangert@gentoo.org">Thilo Bangert</mail> and <mail
link="terjekv@math.uio.no">Terje Kvernes</mail> for their help and comments on
this document.
</p>

</body>
</section>
</chapter>
</guide>
1	neysx	1.1	<?xml version='1.0' encoding="UTF-8"?>
2	swift	1.11	<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/lvm2.xml,v 1.10 2005/02/13 14:01:22 aaby Exp $ -->
3	neysx	1.1	<!DOCTYPE guide SYSTEM "/dtd/guide.dtd">
4
5			<guide link = "/doc/en/lvm2.xml">
6			<title>Gentoo LVM2 installation</title>
7			<author title="Author">
8			<mail link="avi@CFFtechnologies.com">Avi Schwartz</mail>
9			</author>
10			<author title="Contributor">
11			<mail link="rajiv@gentoo.org">Rajiv Manglani</mail>
12			</author>
13			<author title="Editor">
14			<mail link="neysx@gentoo.org">Xavier Neys</mail>
15			</author>
16
17			<abstract>
18			This guide describes how to setup your Gentoo machine using the Logical Volume
19			Manager version 2 (LVM2).
20			</abstract>
21
22			<license/>
23
24	swift	1.11	<version>2.0.7</version>
25			<date>2005-04-07</date>
26	neysx	1.1
27			<chapter>
28			<title>Introduction</title>
29			<section>
30			<body>
31	swift	1.4
32	neysx	1.1	<p>
33			This guide is based on an example with two IDE hard disks. It means that you
34			will more than likely need to change the drive, partition names and partition
35			sizes to match your own setup and needs.
36			</p>
37
38			<warn>
39			This document is not intended to be an LVM2 tutorial. It serves as a
40			supplement to the Gentoo installation procedure as described in the <uri
41	swift	1.4	link="/doc/en/handbook/handbook-x86.xml?part=1&chap=0">Handbook, Part
42			1</uri>. Make sure you <c>read</c> the Gentoo Installation Manual
43			<c>before</c> you start your installation process.
44	neysx	1.1	</warn>
45
46			<note>
47			For a complete LVM HOWTO point your browser to
48			<uri>http://tldp.org/HOWTO/LVM-HOWTO</uri>
49			</note>
50	swift	1.4
51	neysx	1.1	</body>
52			</section>
53			<section>
54			<title>Initial requirements</title>
55			<body>
56	swift	1.4
57	neysx	1.1	<p>
58			If you do a fresh install of Gentoo, you will need to use a bootable CD with
59			LVM2 support such as a Gentoo LiveCD. You can find the LiveCD for an x86
60			architecture on our <uri
61			link="http://www.gentoo.org/main/en/mirrors.xml">mirrors</uri> under
62	neysx	1.9	<path>/releases/x86/2004.3/livecd</path>. Other architectures might
63	neysx	1.1	be supported as well.
64			</p>
65
66			<p>
67	aaby	1.10	If you install LVM2 on a currently running system with some spare hard disk
68	neysx	1.1	space, you will need to enable the LVM2 module (<path>dm-mod</path>). This
69			module is available in <path>gentoo-sources</path>, in
70			<path>development-sources</path> and in <path>gentoo-dev-sources</path>.
71			Compiling your kernel and getting LVM2 to work is covered later in this guide.
72			</p>
73	swift	1.4
74	swift	1.7	<p>
75			Not all 2.4 kernels provided by Gentoo support LVM2!
76			</p>
77
78	swift	1.11	<warn>
79			The LVM2 available on the 2005.0 installation CDs is erroneously linked
80			dynamically against a library (libgpm) which resides in /usr. This means you
81			cannot have your /usr in an LVM environment as well. Either install the latest
82			version or version 2.0.33 (not -r1) which are built statically.
83			</warn>
84
85	neysx	1.1	</body>
86			</section>
87			<section>
88			<title>Partitions</title>
89			<body>
90	swift	1.4
91	neysx	1.1	<p>
92	aaby	1.10	Our example system has two IDE hard disks and will be partitioned as follows:
93	neysx	1.1	</p>
94
95			<ul>
96	swift	1.4	<li>/dev/hda1 -- /boot</li>
97			<li>/dev/hda2 -- (swap)</li>
98			<li>/dev/hda3 -- /</li>
99			<li>/dev/hda4 -- Will be used by LVM2</li>
100			<li>/dev/hdb1 -- Will be used by LVM2</li>
101	neysx	1.1	</ul>
102
103			<impo>
104			Pay attention to the partition names as it is easy to confuse the a's and b's,
105			and the partition numbers. One false move could wipe out the wrong partition.
106			You have been warned!
107			</impo>
108
109			<p>
110			OK, time to start...
111			</p>
112	swift	1.4
113	neysx	1.1	</body>
114			</section>
115			</chapter>
116
117			<chapter>
118			<title>Installation</title>
119			<section>
120			<body>
121
122	swift	1.4	<p>
123	swift	1.8	Follow the handbook, but with the following amendments to chapter <c>4.
124			Preparing the Disks</c>:
125	swift	1.4	</p>
126	neysx	1.1
127	swift	1.4	<p>
128	neysx	1.1	Use <c>fdisk</c> as described in the handbook, but use the partition scheme
129			mentioned above as an example. It is only <e>an example</e>, adapt it to your
130			own needs.
131	swift	1.4	</p>
132	neysx	1.1
133	swift	1.4	<p>
134	neysx	1.1	Create a small physical /boot partition (hda1). In this example, /boot will be
135			not managed by LVM2. This partition will contain your bootloader and your
136			kernel(s). A 64MB partition should be well enough for quite a few kernel
137			generations.
138	swift	1.4	</p>
139	neysx	1.1
140	swift	1.4	<p>
141	neysx	1.1	Create a swap partition (hda2) and activate it.
142	swift	1.4	</p>
143
144	neysx	1.1	<pre caption="Activating the swap partition">
145			# <i>mkswap /dev/hda2</i>
146			# <i>swapon /dev/hda2</i>
147			</pre>
148
149	swift	1.4	<p>
150	neysx	1.1	Create a / (root) partition (hda3). If you are interested in trying to put
151			your root partition under LVM management (which we do not recommend), see the
152			resources section at the end of this guide for a link to a mini-howto on how to
153			do this. The size of the root partition need not be large if you will keep
154			<path>/opt /usr /home /var</path> and <path>/tmp</path> in an LVM2 Volume Group
155			(vg). In this case, 150M is sufficient.
156	swift	1.4	</p>
157	neysx	1.1
158			<note>
159			It is <b>not</b> recommended to put the following directories in an
160	swift	1.4	LVM2 partition: <path>/etc</path>, <path>/lib</path>, <path>/mnt</path>,
161	aaby	1.10	<path>/proc</path>, <path>/sbin</path>, <path>/dev</path>, and <path>/root</path>.
162	neysx	1.1	This way, you would still be able to log into your system (crippled, but
163			still somewhat usable, as root) if something goes terribly wrong.
164			</note>
165
166	swift	1.4	<p>
167	neysx	1.1	Assuming the /boot, swap and root partitions do not use the whole physical disk,
168			create a fourth partition on this disk and set it to type 8e (Linux LVM).
169			If you have more physical drives you would like to use with LVM, create
170			one partition on each and give them the same type (8e).
171	swift	1.4	</p>
172	neysx	1.1
173			<note>
174			Considering the huge size of current disks, you might consider splitting your
175			hard disks into smaller partitions instead of creating a big partition that
176			will be added to an LVM2 volume group in one block. LVM2 makes it easy to
177			extend your volumes after all. This leaves you some unallocated partitions you
178			might need to use outside of an LVM2 group. In short, don't use your disk space
179			until you know you need it. As an example, one contributor had split his
180			160 Gb hard disk into 8 partitions of 20 Gb each.
181			</note>
182
183	swift	1.4	<p>
184	neysx	1.9	Load the LVM2 <path>dm-mod</path> module.
185	swift	1.4	</p>
186	neysx	1.1
187			<pre caption="Loading the LVM2 module">
188			# <i>modprobe dm-mod</i>
189			</pre>
190
191	swift	1.4	<p>
192	neysx	1.1	Scan and activate LVM:
193	swift	1.4	</p>
194
195	neysx	1.1	<pre caption="Activating LVM">
196			<comment>(Avoid scanning your cdrom)</comment>
197	swift	1.8	# <i>mkdir -p /etc/lvm</i>
198	neysx	1.1	# <i>echo 'devices { filter=["r/cdrom/"] }' >/etc/lvm/lvm.conf</i>
199			# <i>vgscan</i>
200			Reading all physical volumes. This may take a while...
201			No volume groups found
202	neysx	1.9	<comment>(Make any previously set up volume groups available)</comment>
203			# <i>vgchange -a y</i>
204	neysx	1.1	</pre>
205
206	swift	1.4	<p>
207	neysx	1.1	Prepare the partitions.
208	swift	1.4	</p>
209	neysx	1.1
210			<pre caption="Preparing the partitions">
211			# <i>pvcreate /dev/hda4 /dev/hdb1</i>
212			No physical volume label read from /dev/hda4
213			Physical volume "/dev/hda4" successfully created
214			No physical volume label read from /dev/hdb1
215			Physical volume "/dev/hdb1" successfully created
216			</pre>
217
218	swift	1.4	<p>
219	neysx	1.1	Setup a volume group. A volume group is the result of combining several
220			physical units into a single logical device.
221	swift	1.4	</p>
222	neysx	1.1
223			<p>
224			In our example, <path>/dev/hda1</path>, <path>/dev/hda2</path> and
225			<path>/dev/hda3</path> are the <path>/boot</path>, swap and root partitions so
226			we need to combine <path>/dev/hda4</path> and <path>/dev/hdb1</path>. It can be
227			done with a single command, but, as an example, we will create our volume group
228			and extend it.
229			</p>
230
231			<pre caption="Creating and extending a volume group">
232			<comment>(Create a volume group named vg)</comment>
233			# <i>vgcreate vg /dev/hda4</i>
234			/etc/lvm/backup: fsync failed: Invalid argument <comment>(Ignore this warning)</comment>
235			Volume group "vg" successfully created
236			<comment>(Extending an existing volume group)</comment>
237			# <i>vgextend vg /dev/hdb1</i>
238			/etc/lvm/backup: fsync failed: Invalid argument <comment>(Ignore this warning, again and later as well)</comment>
239			Volume group "vg" successfully extended
240			</pre>
241
242	swift	1.4	<p>
243	neysx	1.1	Create the logical volumes. Logical volumes are the equivalent of partitions
244			you would create using fdisk in a non LVM2 environment. In our example, we
245			create the following partitions:
246	swift	1.4	</p>
247	neysx	1.1
248			<table>
249			<tr>
250	swift	1.4	<th>Directory</th>
251			<th>Size</th>
252	neysx	1.1	</tr>
253			<tr>
254	swift	1.4	<ti>/usr</ti>
255			<ti>10 GB</ti>
256	neysx	1.1	</tr>
257			<tr>
258	swift	1.4	<ti>/home</ti>
259			<ti>5 GB</ti>
260	neysx	1.1	</tr>
261			<tr>
262	swift	1.4	<ti>/opt</ti>
263			<ti>5 GB</ti>
264	neysx	1.1	</tr>
265			<tr>
266	swift	1.4	<ti>/var</ti>
267			<ti>10 GB</ti>
268	neysx	1.1	</tr>
269			<tr>
270	swift	1.4	<ti>/tmp</ti>
271			<ti>2 GB</ti>
272	neysx	1.1	</tr>
273			</table>
274
275			<p>
276			Since we are going to use LVM2, we should not worry too much about partition
277			sizes because they can always be expanded as needed.
278			</p>
279
280			<note>
281			As Terje Kvernes commented, it is easier to increase the size of a partition
282	aaby	1.10	then to shrink it. You might therefore want to start with smaller partitions
283	neysx	1.1	and increase their size as needed.
284			</note>
285
286			<pre caption="Creating and extending logical volumes">
287			# <i>lvcreate -L10G -nusr vg</i>
288			Logical volume "usr" created <comment>(Further similar messages not displayed)</comment>
289			# <i>lvcreate -L5G -nhome vg</i>
290			# <i>lvcreate -L5G -nopt vg</i>
291			# <i>lvcreate -L10G -nvar vg</i>
292			# <i>lvcreate -L2G -ntmp vg</i>
293	swift	1.5	<comment>(As an example, let's extend a logical volume with 5 extra Gbytes)</comment>
294			# <i>lvextend -L+5G /dev/vg/home</i>
295	neysx	1.1	</pre>
296
297	swift	1.4	<p>
298	neysx	1.1	Create filesystems on the logical volumes the same way you would on a regular
299			partition. We use ext3 on the logical volumes but any filesystem of your
300			choice will work:
301	swift	1.4	</p>
302	neysx	1.1
303			<pre caption="Creating the filesystems">
304			# <i>mke2fs -j /dev/vg/usr</i>
305			# <i>mke2fs -j /dev/vg/home</i>
306			# <i>mke2fs -j /dev/vg/opt</i>
307			# <i>mke2fs -j /dev/vg/var</i>
308			# <i>mke2fs -j /dev/vg/tmp</i>
309			</pre>
310
311	swift	1.4	<p>
312	neysx	1.1	Mount your partitions as described in the handbook and mount your LVM2 logical
313			volumes as if they were partitions. Replace the usual <path>/dev/hdxx</path>
314			with <path>/dev/vg/logical_volumename</path>.
315	swift	1.4	</p>
316	neysx	1.1
317			<pre caption="Mounting your logical volumes">
318			<comment>(Make sure you have mounted your root partition as described in the handbook first)</comment>
319			# <i>mkdir /mnt/gentoo/usr</i>
320			# <i>mount /dev/vg/usr /mnt/gentoo/usr</i>
321			# <i>mkdir /mnt/gentoo/home</i>
322			# <i>mount /dev/vg/home /mnt/gentoo/home</i>
323			# <i>mkdir /mnt/gentoo/opt</i>
324			# <i>mount /dev/vg/opt /mnt/gentoo/opt</i>
325			# <i>mkdir /mnt/gentoo/var</i>
326			# <i>mount /dev/vg/var /mnt/gentoo/var</i>
327			# <i>mkdir /mnt/gentoo/tmp</i>
328			# <i>mount /dev/vg/tmp /mnt/gentoo/tmp</i>
329			</pre>
330
331			<note>
332			The rest of the installation handbook is mostly unchanged so we shall not
333			walk you through it again except to point out differences.
334			</note>
335
336	swift	1.4	<p>
337	neysx	1.1	When configuring your kernel, make sure to configure your kernel to
338	swift	1.6	support LVM2 (not all 2.4 kernels do). Select the LVM2 module as follows:
339	swift	1.4	</p>
340	neysx	1.1
341	aaby	1.10	<pre caption="Selecting the LVM2 module in a 2.4.x kernel">
342	neysx	1.1	Multi-device support (RAID and LVM) --->
343			[*] Multiple devices driver support (RAID and LVM)
344			< > RAID support
345			<comment>(Note that LVM is not selected on purpose, this was for LVM1)</comment>
346			< > Logical volume manager (LVM) support
347			<M> Device-mapper support
348			< > Mirror (RAID-1) support
349			</pre>
350
351	aaby	1.10	<pre caption="Selecting the LVM2 module in a 2.6.x kernel">
352	neysx	1.1	Device Drivers --->
353			Multi-device support (RAID and LVM) --->
354			[*] Multiple devices driver support (RAID and LVM)
355			< > RAID support
356			<M> Device mapper support
357			</pre>
358
359			<p>
360			The compiled module is called <path>dm-mod.ko</path>
361			</p>
362
363			<p>
364			After you have built your kernel and installed its modules, add the following
365			line to your <path>/etc/modules.autoload.d/kernel-{KV}</path> where {KV}
366			represents your kernel version (2.4 or 2.6) so that the LVM2 module gets loaded
367			when your machine is booted:
368			</p>
369
370			<pre caption="Adding the LVM2 module into /etc/modules.autoload.d/kernel-2.6">
371			# <i>nano -w /etc/modules.autoload.d/kernel-2.6</i>
372			<comment>(Add the following line)</comment>
373			dm-mod
374			</pre>
375
376			<p>
377			Now, install the lvm2 package.
378			</p>
379
380			<impo>
381			Make sure your <path>/usr/src/linux</path> link points to the kernel sources you
382			are using because the lvm2 ebuild depends on the device-mapper ebuild which
383			will check the presence of a required source file under
384			<path>/usr/src/linux/include/linux</path>.
385			</impo>
386
387			<pre caption="Emerging the LVM2 package">
388			# <i>emerge lvm2</i>
389	neysx	1.9	<comment>(At the time of writing, the stable version is 2.00.08.
390			With version 2.00.08, prevent lvm2 from probing your cdrom by doing:</comment>
391	neysx	1.1	# <i>echo 'devices { filter=["r/cdrom/"] }' >> /etc/lvm/lvm.conf</i>
392	neysx	1.9
393			<comment>(Versions 2.00.15 and later come with a /etc/lvm/lvm.conf
394			Edit your /etc/lvm/lvm.conf and follow the comments</comment>
395			# <i>nano -w /etc/lvm/lvm.conf</i>
396	neysx	1.1	</pre>
397
398	swift	1.4	<p>
399	neysx	1.1	When editing your <path>/etc/fstab</path> file, follow the handbook and add
400			your LVM2 logical volumes as needed. Again, here are a few lines needed for
401			our example:
402	swift	1.4	</p>
403	neysx	1.1
404			<pre caption="Extract of /etc/fstab">
405			/dev/hda1 /boot ext3 noauto,noatime 1 1
406			/dev/hda2 none swap sw 0 0
407			/dev/hda3 / ext3 noatime 0 0
408			# Logical volumes
409			/dev/vg/usr /usr ext3 noatime 0 0
410			/dev/vg/home /home ext3 noatime 0 0
411			/dev/vg/opt /opt ext3 noatime 0 0
412			/dev/vg/var /var ext3 noatime 0 0
413			/dev/vg/tmp /tmp ext3 noatime 0 0
414			</pre>
415
416	swift	1.4	<p>
417	neysx	1.1	When you reach the end of the installation part of the handbook, don't forget
418			to umount all your LVM2 logical volumes as well and for a good measure run the
419			following command before you reboot:
420	swift	1.4	</p>
421	neysx	1.1
422			<pre caption="Shutting down LVM2">
423	neysx	1.9	# <i>vgchange -a n</i>
424	neysx	1.1	</pre>
425
426	swift	1.4	<p>
427	neysx	1.1	Restart your machine and all partitions should be visible and mounted.
428	swift	1.4	</p>
429
430	neysx	1.1	</body>
431			</section>
432			</chapter>
433
434			<chapter>
435			<title>Resources</title>
436			<section>
437			<body>
438	swift	1.4
439	neysx	1.1	<ul>
440	swift	1.4	<li>
441			The official <uri link="http://sources.redhat.com/lvm2">LVM2 home page</uri>
442			</li>
443			<li>
444			The <uri link="http://tldp.org/HOWTO/LVM-HOWTO">LVM Howto</uri>
445			</li>
446			<li>
447			Daniel Robbins's articles on LVM at IBM's DeveloperWorks:
448			<uri>http://www-106.ibm.com/developerworks/linux/library/l-lvm/?dwzone=linux</uri>
449			and
450			<uri>http://www-106.ibm.com/developerworks/linux/library/l-lvm2.html?dwzone=linux</uri>
451			</li>
452			<li>
453			How to boot your root FS off of LVM1:
454			<uri>http://www.the-infinite.org/archive/docs/lvm/howto-boot-off-root-lv.txt</uri>
455			</li>
456	neysx	1.1	</ul>
457
458			</body>
459			</section>
460			</chapter>
461	swift	1.4
462	neysx	1.1	<chapter>
463			<title>Acknowledgements</title>
464			<section>
465			<body>
466
467			<p>
468			Thanks <mail link="bangert@gentoo.org">Thilo Bangert</mail> and <mail
469			link="terjekv@math.uio.no">Terje Kvernes</mail> for their help and comments on
470			this document.
471			</p>
472
473			</body>
474			</section>
475			</chapter>
476			</guide>