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<?xml version='1.0' encoding="UTF-8"?> |
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<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/lvm2.xml,v 1.8 2004/09/25 12:42:43 swift Exp $ --> |
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<!DOCTYPE guide SYSTEM "/dtd/guide.dtd"> |
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|
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<guide link = "/doc/en/lvm2.xml"> |
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<title>Gentoo LVM2 installation</title> |
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<author title="Author"> |
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<mail link="avi@CFFtechnologies.com">Avi Schwartz</mail> |
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</author> |
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<author title="Contributor"> |
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<mail link="rajiv@gentoo.org">Rajiv Manglani</mail> |
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</author> |
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<author title="Editor"> |
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<mail link="neysx@gentoo.org">Xavier Neys</mail> |
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</author> |
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|
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<abstract> |
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This guide describes how to setup your Gentoo machine using the Logical Volume |
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Manager version 2 (LVM2). |
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</abstract> |
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|
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<license/> |
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|
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<version>2.0.6</version> |
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<date>2004-11-21</date> |
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|
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<chapter> |
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<title>Introduction</title> |
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<section> |
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<body> |
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|
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<p> |
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This guide is based on an example with two IDE hard disks. It means that you |
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will more than likely need to change the drive, partition names and partition |
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sizes to match your own setup and needs. |
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</p> |
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|
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<warn> |
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This document is not intended to be an LVM2 tutorial. It serves as a |
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supplement to the Gentoo installation procedure as described in the <uri |
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link="/doc/en/handbook/handbook-x86.xml?part=1&chap=0">Handbook, Part |
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1</uri>. Make sure you <c>read</c> the Gentoo Installation Manual |
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<c>before</c> you start your installation process. |
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</warn> |
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|
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<note> |
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For a complete LVM HOWTO point your browser to |
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<uri>http://tldp.org/HOWTO/LVM-HOWTO</uri> |
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</note> |
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|
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</body> |
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</section> |
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<section> |
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<title>Initial requirements</title> |
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<body> |
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|
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<p> |
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If you do a fresh install of Gentoo, you will need to use a bootable CD with |
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LVM2 support such as a Gentoo LiveCD. You can find the LiveCD for an x86 |
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architecture on our <uri |
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link="http://www.gentoo.org/main/en/mirrors.xml">mirrors</uri> under |
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<path>/releases/x86/2004.3/livecd</path>. Other architectures might |
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be supported as well. |
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</p> |
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|
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<p> |
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It you install LVM2 on a currently running system with some spare hard disk |
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space, you will need to enable the LVM2 module (<path>dm-mod</path>). This |
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module is available in <path>gentoo-sources</path>, in |
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<path>development-sources</path> and in <path>gentoo-dev-sources</path>. |
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Compiling your kernel and getting LVM2 to work is covered later in this guide. |
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</p> |
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|
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<p> |
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Not all 2.4 kernels provided by Gentoo support LVM2! |
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</p> |
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|
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</body> |
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</section> |
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<section> |
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<title>Partitions</title> |
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<body> |
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|
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<p> |
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Our example system has 2 IDE hard disks and will be partitioned as follows: |
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</p> |
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|
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<ul> |
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<li>/dev/hda1 -- /boot</li> |
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<li>/dev/hda2 -- (swap)</li> |
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<li>/dev/hda3 -- /</li> |
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<li>/dev/hda4 -- Will be used by LVM2</li> |
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<li>/dev/hdb1 -- Will be used by LVM2</li> |
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</ul> |
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|
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<impo> |
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Pay attention to the partition names as it is easy to confuse the a's and b's, |
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and the partition numbers. One false move could wipe out the wrong partition. |
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You have been warned! |
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</impo> |
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|
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<p> |
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OK, time to start... |
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</p> |
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|
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</body> |
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</section> |
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</chapter> |
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|
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<chapter> |
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<title>Installation</title> |
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<section> |
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<body> |
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|
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<p> |
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Follow the handbook, but with the following amendments to chapter <c>4. |
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Preparing the Disks</c>: |
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</p> |
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|
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<p> |
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Use <c>fdisk</c> as described in the handbook, but use the partition scheme |
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mentioned above as an example. It is only <e>an example</e>, adapt it to your |
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own needs. |
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</p> |
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|
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<p> |
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Create a small physical /boot partition (hda1). In this example, /boot will be |
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not managed by LVM2. This partition will contain your bootloader and your |
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kernel(s). A 64MB partition should be well enough for quite a few kernel |
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generations. |
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</p> |
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|
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<p> |
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Create a swap partition (hda2) and activate it. |
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</p> |
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|
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<pre caption="Activating the swap partition"> |
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# <i>mkswap /dev/hda2</i> |
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# <i>swapon /dev/hda2</i> |
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</pre> |
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|
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<p> |
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Create a / (root) partition (hda3). If you are interested in trying to put |
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your root partition under LVM management (which we do not recommend), see the |
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resources section at the end of this guide for a link to a mini-howto on how to |
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do this. The size of the root partition need not be large if you will keep |
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<path>/opt /usr /home /var</path> and <path>/tmp</path> in an LVM2 Volume Group |
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(vg). In this case, 150M is sufficient. |
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</p> |
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|
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<note> |
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It is <b>not</b> recommended to put the following directories in an |
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LVM2 partition: <path>/etc</path>, <path>/lib</path>, <path>/mnt</path>, |
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<path>/proc</path>, <path>/sbin</path>, <path>/dev</path>, <path>/root</path>. |
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This way, you would still be able to log into your system (crippled, but |
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still somewhat usable, as root) if something goes terribly wrong. |
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</note> |
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|
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<p> |
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Assuming the /boot, swap and root partitions do not use the whole physical disk, |
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create a fourth partition on this disk and set it to type 8e (Linux LVM). |
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If you have more physical drives you would like to use with LVM, create |
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one partition on each and give them the same type (8e). |
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</p> |
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|
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<note> |
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Considering the huge size of current disks, you might consider splitting your |
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hard disks into smaller partitions instead of creating a big partition that |
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will be added to an LVM2 volume group in one block. LVM2 makes it easy to |
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extend your volumes after all. This leaves you some unallocated partitions you |
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might need to use outside of an LVM2 group. In short, don't use your disk space |
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until you know you need it. As an example, one contributor had split his |
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160 Gb hard disk into 8 partitions of 20 Gb each. |
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</note> |
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|
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<p> |
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Load the LVM2 <path>dm-mod</path> module. |
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</p> |
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|
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<pre caption="Loading the LVM2 module"> |
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# <i>modprobe dm-mod</i> |
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</pre> |
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|
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<p> |
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Scan and activate LVM: |
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</p> |
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|
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<pre caption="Activating LVM"> |
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<comment>(Avoid scanning your cdrom)</comment> |
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# <i>mkdir -p /etc/lvm</i> |
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# <i>echo 'devices { filter=["r/cdrom/"] }' >/etc/lvm/lvm.conf</i> |
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# <i>vgscan</i> |
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Reading all physical volumes. This may take a while... |
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No volume groups found |
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<comment>(Make any previously set up volume groups available)</comment> |
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# <i>vgchange -a y</i> |
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</pre> |
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|
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<p> |
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Prepare the partitions. |
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</p> |
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|
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<pre caption="Preparing the partitions"> |
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# <i>pvcreate /dev/hda4 /dev/hdb1</i> |
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No physical volume label read from /dev/hda4 |
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Physical volume "/dev/hda4" successfully created |
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No physical volume label read from /dev/hdb1 |
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Physical volume "/dev/hdb1" successfully created |
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</pre> |
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|
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<p> |
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Setup a volume group. A volume group is the result of combining several |
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physical units into a single logical device. |
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</p> |
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|
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<p> |
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In our example, <path>/dev/hda1</path>, <path>/dev/hda2</path> and |
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<path>/dev/hda3</path> are the <path>/boot</path>, swap and root partitions so |
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we need to combine <path>/dev/hda4</path> and <path>/dev/hdb1</path>. It can be |
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done with a single command, but, as an example, we will create our volume group |
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and extend it. |
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</p> |
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|
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<pre caption="Creating and extending a volume group"> |
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<comment>(Create a volume group named vg)</comment> |
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# <i>vgcreate vg /dev/hda4</i> |
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/etc/lvm/backup: fsync failed: Invalid argument <comment>(Ignore this warning)</comment> |
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Volume group "vg" successfully created |
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<comment>(Extending an existing volume group)</comment> |
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# <i>vgextend vg /dev/hdb1</i> |
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/etc/lvm/backup: fsync failed: Invalid argument <comment>(Ignore this warning, again and later as well)</comment> |
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Volume group "vg" successfully extended |
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</pre> |
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|
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<p> |
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Create the logical volumes. Logical volumes are the equivalent of partitions |
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you would create using fdisk in a non LVM2 environment. In our example, we |
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create the following partitions: |
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</p> |
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|
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<table> |
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<tr> |
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<th>Directory</th> |
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<th>Size</th> |
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</tr> |
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<tr> |
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<ti>/usr</ti> |
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<ti>10 GB</ti> |
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</tr> |
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<tr> |
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<ti>/home</ti> |
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<ti>5 GB</ti> |
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</tr> |
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<tr> |
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<ti>/opt</ti> |
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<ti>5 GB</ti> |
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</tr> |
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<tr> |
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<ti>/var</ti> |
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<ti>10 GB</ti> |
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</tr> |
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<tr> |
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<ti>/tmp</ti> |
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<ti>2 GB</ti> |
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</tr> |
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</table> |
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|
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<p> |
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Since we are going to use LVM2, we should not worry too much about partition |
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sizes because they can always be expanded as needed. |
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</p> |
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|
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<note> |
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As Terje Kvernes commented, it is easier to increase the size of a partition |
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then to shrink it. You might want therefore to start with smaller partitions |
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and increase their size as needed. |
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</note> |
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|
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<pre caption="Creating and extending logical volumes"> |
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# <i>lvcreate -L10G -nusr vg</i> |
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Logical volume "usr" created <comment>(Further similar messages not displayed)</comment> |
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# <i>lvcreate -L5G -nhome vg</i> |
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# <i>lvcreate -L5G -nopt vg</i> |
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# <i>lvcreate -L10G -nvar vg</i> |
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# <i>lvcreate -L2G -ntmp vg</i> |
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<comment>(As an example, let's extend a logical volume with 5 extra Gbytes)</comment> |
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# <i>lvextend -L+5G /dev/vg/home</i> |
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</pre> |
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|
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<p> |
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Create filesystems on the logical volumes the same way you would on a regular |
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partition. We use ext3 on the logical volumes but any filesystem of your |
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choice will work: |
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</p> |
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|
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<pre caption="Creating the filesystems"> |
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# <i>mke2fs -j /dev/vg/usr</i> |
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# <i>mke2fs -j /dev/vg/home</i> |
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# <i>mke2fs -j /dev/vg/opt</i> |
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# <i>mke2fs -j /dev/vg/var</i> |
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# <i>mke2fs -j /dev/vg/tmp</i> |
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</pre> |
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|
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<p> |
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Mount your partitions as described in the handbook and mount your LVM2 logical |
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volumes as if they were partitions. Replace the usual <path>/dev/hdxx</path> |
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with <path>/dev/vg/logical_volumename</path>. |
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</p> |
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|
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<pre caption="Mounting your logical volumes"> |
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<comment>(Make sure you have mounted your root partition as described in the handbook first)</comment> |
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# <i>mkdir /mnt/gentoo/usr</i> |
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# <i>mount /dev/vg/usr /mnt/gentoo/usr</i> |
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# <i>mkdir /mnt/gentoo/home</i> |
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# <i>mount /dev/vg/home /mnt/gentoo/home</i> |
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# <i>mkdir /mnt/gentoo/opt</i> |
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# <i>mount /dev/vg/opt /mnt/gentoo/opt</i> |
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# <i>mkdir /mnt/gentoo/var</i> |
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# <i>mount /dev/vg/var /mnt/gentoo/var</i> |
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# <i>mkdir /mnt/gentoo/tmp</i> |
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# <i>mount /dev/vg/tmp /mnt/gentoo/tmp</i> |
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</pre> |
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|
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<note> |
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The rest of the installation handbook is mostly unchanged so we shall not |
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walk you through it again except to point out differences. |
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</note> |
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|
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<p> |
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When configuring your kernel, make sure to configure your kernel to |
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support LVM2 (not all 2.4 kernels do). Select the LVM2 module as follows: |
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</p> |
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|
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<pre caption="Selecting the LVM2 module in a kernel 2.4.x"> |
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Multi-device support (RAID and LVM) ---> |
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[*] Multiple devices driver support (RAID and LVM) |
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< > RAID support |
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<comment>(Note that LVM is not selected on purpose, this was for LVM1)</comment> |
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< > Logical volume manager (LVM) support |
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<M> Device-mapper support |
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< > Mirror (RAID-1) support |
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</pre> |
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|
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<pre caption="Selecting the LVM2 module in a kernel 2.6.x"> |
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Device Drivers ---> |
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Multi-device support (RAID and LVM) ---> |
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[*] Multiple devices driver support (RAID and LVM) |
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< > RAID support |
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<M> Device mapper support |
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</pre> |
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|
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<p> |
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The compiled module is called <path>dm-mod.ko</path> |
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</p> |
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|
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<p> |
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After you have built your kernel and installed its modules, add the following |
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line to your <path>/etc/modules.autoload.d/kernel-{KV}</path> where {KV} |
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represents your kernel version (2.4 or 2.6) so that the LVM2 module gets loaded |
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when your machine is booted: |
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</p> |
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|
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<pre caption="Adding the LVM2 module into /etc/modules.autoload.d/kernel-2.6"> |
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# <i>nano -w /etc/modules.autoload.d/kernel-2.6</i> |
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<comment>(Add the following line)</comment> |
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dm-mod |
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</pre> |
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|
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<p> |
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Now, install the lvm2 package. |
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</p> |
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|
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<impo> |
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Make sure your <path>/usr/src/linux</path> link points to the kernel sources you |
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are using because the lvm2 ebuild depends on the device-mapper ebuild which |
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will check the presence of a required source file under |
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<path>/usr/src/linux/include/linux</path>. |
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</impo> |
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|
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<pre caption="Emerging the LVM2 package"> |
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# <i>emerge lvm2</i> |
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<comment>(At the time of writing, the stable version is 2.00.08. |
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With version 2.00.08, prevent lvm2 from probing your cdrom by doing:</comment> |
| 384 |
# <i>echo 'devices { filter=["r/cdrom/"] }' >> /etc/lvm/lvm.conf</i> |
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|
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<comment>(Versions 2.00.15 and later come with a /etc/lvm/lvm.conf |
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Edit your /etc/lvm/lvm.conf and follow the comments</comment> |
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# <i>nano -w /etc/lvm/lvm.conf</i> |
| 389 |
</pre> |
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|
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<p> |
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When editing your <path>/etc/fstab</path> file, follow the handbook and add |
| 393 |
your LVM2 logical volumes as needed. Again, here are a few lines needed for |
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our example: |
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</p> |
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|
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<pre caption="Extract of /etc/fstab"> |
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/dev/hda1 /boot ext3 noauto,noatime 1 1 |
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/dev/hda2 none swap sw 0 0 |
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/dev/hda3 / ext3 noatime 0 0 |
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# Logical volumes |
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/dev/vg/usr /usr ext3 noatime 0 0 |
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/dev/vg/home /home ext3 noatime 0 0 |
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/dev/vg/opt /opt ext3 noatime 0 0 |
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/dev/vg/var /var ext3 noatime 0 0 |
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/dev/vg/tmp /tmp ext3 noatime 0 0 |
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</pre> |
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|
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<p> |
| 410 |
When you reach the end of the installation part of the handbook, don't forget |
| 411 |
to umount all your LVM2 logical volumes as well and for a good measure run the |
| 412 |
following command before you reboot: |
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</p> |
| 414 |
|
| 415 |
<pre caption="Shutting down LVM2"> |
| 416 |
# <i>vgchange -a n</i> |
| 417 |
</pre> |
| 418 |
|
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<p> |
| 420 |
Restart your machine and all partitions should be visible and mounted. |
| 421 |
</p> |
| 422 |
|
| 423 |
</body> |
| 424 |
</section> |
| 425 |
</chapter> |
| 426 |
|
| 427 |
<chapter> |
| 428 |
<title>Resources</title> |
| 429 |
<section> |
| 430 |
<body> |
| 431 |
|
| 432 |
<ul> |
| 433 |
<li> |
| 434 |
The official <uri link="http://sources.redhat.com/lvm2">LVM2 home page</uri> |
| 435 |
</li> |
| 436 |
<li> |
| 437 |
The <uri link="http://tldp.org/HOWTO/LVM-HOWTO">LVM Howto</uri> |
| 438 |
</li> |
| 439 |
<li> |
| 440 |
Daniel Robbins's articles on LVM at IBM's DeveloperWorks: |
| 441 |
<uri>http://www-106.ibm.com/developerworks/linux/library/l-lvm/?dwzone=linux</uri> |
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and |
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<uri>http://www-106.ibm.com/developerworks/linux/library/l-lvm2.html?dwzone=linux</uri> |
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</li> |
| 445 |
<li> |
| 446 |
How to boot your root FS off of LVM1: |
| 447 |
<uri>http://www.the-infinite.org/archive/docs/lvm/howto-boot-off-root-lv.txt</uri> |
| 448 |
</li> |
| 449 |
</ul> |
| 450 |
|
| 451 |
</body> |
| 452 |
</section> |
| 453 |
</chapter> |
| 454 |
|
| 455 |
<chapter> |
| 456 |
<title>Acknowledgements</title> |
| 457 |
<section> |
| 458 |
<body> |
| 459 |
|
| 460 |
<p> |
| 461 |
Thanks <mail link="bangert@gentoo.org">Thilo Bangert</mail> and <mail |
| 462 |
link="terjekv@math.uio.no">Terje Kvernes</mail> for their help and comments on |
| 463 |
this document. |
| 464 |
</p> |
| 465 |
|
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</body> |
| 467 |
</section> |
| 468 |
</chapter> |
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</guide> |
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