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<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook V4.2//EN" [
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]>
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  <article class="specification">
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  <articleinfo>
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    <title>Ganeti installation tutorial</title>
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  </articleinfo>
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  <para>Documents Ganeti version 1.2</para>
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  <sect1>
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    <title>Introduction</title>
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    <para>
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      Ganeti is a cluster virtualization management system based on
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      Xen. This document explains how to bootstrap a Ganeti node (Xen
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      <literal>dom0</literal>), create a running cluster and install
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      virtual instance (Xen <literal>domU</literal>).  You need to
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      repeat most of the steps in this document for every node you
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      want to install, but of course we recommend creating some
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      semi-automatic procedure if you plan to deploy Ganeti on a
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      medium/large scale.
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    </para>
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    <para>
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      A basic Ganeti terminology glossary is provided in the
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      introductory section of the <emphasis>Ganeti administrator's
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      guide</emphasis>. Please refer to that document if you are
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      uncertain about the terms we are using.
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    </para>
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    <para>
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      Ganeti has been developed for Linux and is
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      distribution-agnostic.  This documentation will use Debian Etch
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      as an example system but the examples can easily be translated
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      to any other distribution.  You are expected to be familiar with
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      your distribution, its package management system, and Xen before
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      trying to use Ganeti.
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    </para>
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    <para>This document is divided into two main sections:
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      <itemizedlist>
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        <listitem>
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          <simpara>Installation of the base system and base
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          components</simpara>
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        </listitem>
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        <listitem>
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          <simpara>Configuration of the environment for
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          Ganeti</simpara>
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        </listitem>
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      </itemizedlist>
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    Each of these is divided into sub-sections. While a full Ganeti
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    system will need all of the steps specified, some are not strictly
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    required for every environment. Which ones they are, and why, is
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    specified in the corresponding sections.
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    </para>
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  </sect1>
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  <sect1>
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    <title>Installing the base system and base components</title>
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    <sect2>
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      <title>Hardware requirements</title>
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      <para>
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         Any system supported by your Linux distribution is fine.
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         64-bit systems are better as they can support more memory.
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      </para>
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      <para>
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         Any disk drive recognized by Linux
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         (<literal>IDE</literal>/<literal>SCSI</literal>/<literal>SATA</literal>/etc.)
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         is supported in Ganeti. Note that no shared storage
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         (e.g. <literal>SAN</literal>) is needed to get high-availability features. It is
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         highly recommended to use more than one disk drive to improve
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         speed. But Ganeti also works with one disk per machine.
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      </para>
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    <sect2>
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      <title>Installing the base system</title>
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      <para>
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        <emphasis role="strong">Mandatory</emphasis> on all nodes.
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      </para>
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      <para>
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        It is advised to start with a clean, minimal install of the
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        operating system. The only requirement you need to be aware of
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        at this stage is to partition leaving enough space for a big
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        (<emphasis role="strong">minimum
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        <constant>20GiB</constant></emphasis>) LVM volume group which
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        will then host your instance filesystems. The volume group
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        name Ganeti 1.2 uses (by default) is
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        <emphasis>xenvg</emphasis>.
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      </para>
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      <para>
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        While you can use an existing system, please note that the
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        Ganeti installation is intrusive in terms of changes to the
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        system configuration, and it's best to use a newly-installed
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        system without important data on it.
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      </para>
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      <para>
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        Also, for best results, it's advised that the nodes have as
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        much as possible the same hardware and software
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        configuration. This will make administration much easier.
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      </para>
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      <sect3>
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        <title>Hostname issues</title>
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        <para>
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          Note that Ganeti requires the hostnames of the systems
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          (i.e. what the <computeroutput>hostname</computeroutput>
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          command outputs to be a fully-qualified name, not a short
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          name. In other words, you should use
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          <literal>node1.example.com</literal> as a hostname and not
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          just <literal>node1</literal>.
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        </para>
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        <formalpara>
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          <title>Debian</title>
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          <para>
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            Note that Debian Etch configures the hostname differently
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            than you need it for Ganeti. For example, this is what
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            Etch puts in <filename>/etc/hosts</filename> in certain
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            situations:
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<screen>
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127.0.0.1       localhost
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127.0.1.1       node1.example.com node1
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</screen>
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          but for Ganeti you need to have:
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<screen>
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127.0.0.1       localhost
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192.168.1.1     node1.example.com node1
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</screen>
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            replacing <literal>192.168.1.1</literal> with your node's
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            address. Also, the file <filename>/etc/hostname</filename>
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            which configures the hostname of the system should contain
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            <literal>node1.example.com</literal> and not just
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            <literal>node1</literal> (you need to run the command
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            <computeroutput>/etc/init.d/hostname.sh
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            start</computeroutput> after changing the file).
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          </para>
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        </formalpara>
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      </sect3>
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    </sect2>
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    <sect2>
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      <title>Installing Xen</title>
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      <para>
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        <emphasis role="strong">Mandatory</emphasis> on all nodes.
157
      </para>
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      <para>
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        While Ganeti is developed with the ability to modularly run on
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        different virtualization environments in mind the only one
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        currently useable on a live system is <ulink
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        url="http://xen.xensource.com/">Xen</ulink>. Supported
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        versions are: <simplelist type="inline">
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        <member><literal>3.0.3</literal></member>
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        <member><literal>3.0.4</literal></member>
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        <member><literal>3.1</literal></member> </simplelist>.
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      </para>
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      <para>
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        Please follow your distribution's recommended way to install
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        and set up Xen, or install Xen from the upstream source, if
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        you wish, following their manual.
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      </para>
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      <para>
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        After installing Xen you need to reboot into your Xen-ified
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        dom0 system. On some distributions this might involve
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        configuring GRUB appropriately, whereas others will configure
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        it automatically when you install Xen from a package.
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      </para>
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      <formalpara><title>Debian</title>
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      <para>
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        Under Debian Etch or Sarge+backports you can install the
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        relevant <literal>xen-linux-system</literal> package, which
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        will pull in both the hypervisor and the relevant
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        kernel. Also, if you are installing a 32-bit Etch, you should
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        install the <computeroutput>libc6-xen</computeroutput> package
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        (run <computeroutput>apt-get install
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        libc6-xen</computeroutput>).
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      </para>
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      </formalpara>
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      <sect3>
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        <title>Xen settings</title>
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        <para>
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          It's recommended that dom0 is restricted to a low amount of
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          memory (<constant>512MiB</constant> is reasonable) and that
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          memory ballooning is disabled in the file
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          <filename>/etc/xen/xend-config.sxp</filename> by setting the
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          value <literal>dom0-min-mem</literal> to
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          <constant>0</constant>, like this:
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          <computeroutput>(dom0-min-mem 0)</computeroutput>
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        </para>
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        <para>
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          For optimum performance when running both CPU and I/O
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          intensive instances, it's also recommended that the dom0 is
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          restricted to one CPU only, for example by booting with the
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          kernel parameter <literal>nosmp</literal>.
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        </para>
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        <formalpara>
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          <title>Debian</title>
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          <para>
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            Besides the ballooning change which you need to set in
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            <filename>/etc/xen/xend-config.sxp</filename>, you need to
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            set the memory and nosmp parameters in the file
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            <filename>/boot/grub/menu.lst</filename>. You need to
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            modify the variable <literal>xenhopt</literal> to add
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            <userinput>dom0_mem=512M</userinput> like this:
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<screen>
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## Xen hypervisor options to use with the default Xen boot option
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# xenhopt=dom0_mem=512M
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</screen>
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            and the <literal>xenkopt</literal> needs to include the
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            <userinput>nosmp</userinput> option like this:
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<screen>
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## Xen Linux kernel options to use with the default Xen boot option
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# xenkopt=nosmp
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</screen>
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          Any existing parameters can be left in place: it's ok to
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          have <computeroutput>xenkopt=console=tty0
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          nosmp</computeroutput>, for example. After modifying the
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          files, you need to run:
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<screen>
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/sbin/update-grub
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</screen>
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          </para>
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        </formalpara>
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      </sect3>
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      <sect3>
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        <title>Selecting the instance kernel</title>
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        <para>
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          After you have installed Xen, you need to tell Ganeti
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          exactly what kernel to use for the instances it will
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          create. This is done by creating a
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          <emphasis>symlink</emphasis> from your actual kernel to
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          <filename>/boot/vmlinuz-2.6-xenU</filename>, and one from
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          your initrd to
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          <filename>/boot/initrd-2.6-xenU</filename>. Note that if you
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          don't use an initrd for the <literal>domU</literal> kernel,
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          you don't need to create the initrd symlink.
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        </para>
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        <formalpara>
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          <title>Debian</title>
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          <para>
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            After installation of the
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            <literal>xen-linux-system</literal> package, you need to
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            run (replace the exact version number with the one you
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            have):
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            <screen>
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cd /boot
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ln -s vmlinuz-2.6.18-5-xen-686 vmlinuz-2.6-xenU
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ln -s initrd.img-2.6.18-5-xen-686 initrd-2.6-xenU
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            </screen>
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          </para>
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        </formalpara>
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      </sect3>
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    </sect2>
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    <sect2>
281
      <title>Installing DRBD</title>
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283
      <para>
284
        Recommended on all nodes: <ulink
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        url="http://www.drbd.org/">DRBD</ulink> is required if you
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        want to use the high availability (HA) features of Ganeti, but
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        optional if you don't require HA or only run Ganeti on
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        single-node clusters. You can upgrade a non-HA cluster to an
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        HA one later, but you might need to export and re-import all
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        your instances to take advantage of the new features.
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      </para>
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293
      <para>
294
        Supported DRBD version: the <literal>0.7</literal>
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        series. It's recommended to have at least version
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        <literal>0.7.24</literal> if you use <command>udev</command>
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        since older versions have a bug related to device discovery
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        which can be triggered in cases of hard drive failure.
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      </para>
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301
      <para>
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        Now the bad news: unless your distribution already provides it
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        installing DRBD might involve recompiling your kernel or
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        anyway fiddling with it. Hopefully at least the Xen-ified
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        kernel source to start from will be provided.
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      </para>
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308
      <para>
309
        The good news is that you don't need to configure DRBD at all.
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        Ganeti will do it for you for every instance you set up.  If
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        you have the DRBD utils installed and the module in your
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        kernel you're fine. Please check that your system is
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        configured to load the module at every boot, and that it
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        passes the following option to the module:
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        <computeroutput>minor_count=64</computeroutput> (this will
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        allow you to use up to 32 instances per node).
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      </para>
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319
      <formalpara><title>Debian</title>
320
        <para>
321
         You can just install (build) the DRBD 0.7 module with the
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         following commands (make sure you are running the Xen
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         kernel):
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        </para>
325
      </formalpara>
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      <screen>
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apt-get install drbd0.7-module-source drbd0.7-utils
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m-a update
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m-a a-i drbd0.7
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echo drbd minor_count=64 >> /etc/modules
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modprobe drbd minor_count=64
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      </screen>
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      <para>
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        It is also recommended that you comment out the default
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        resources in the <filename>/etc/dbrd.conf</filename> file, so
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        that the init script doesn't try to configure any drbd
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        devices. You can do this by prefixing all
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        <literal>resource</literal> lines in the file with the keyword
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        <literal>skip</literal>, like this:
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      </para>
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      <screen>
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skip resource r0 {
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...
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}
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skip resource "r1" {
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...
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}
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      </screen>
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    </sect2>
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    <sect2>
357
      <title>Other required software</title>
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359
      <para>Besides Xen and DRBD, you will need to install the
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      following (on all nodes):</para>
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      <itemizedlist>
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        <listitem>
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          <simpara><ulink url="http://sourceware.org/lvm2/">LVM
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          version 2</ulink></simpara>
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        </listitem>
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        <listitem>
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          <simpara><ulink
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          url="http://www.openssl.org/">OpenSSL</ulink></simpara>
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        </listitem>
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        <listitem>
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          <simpara><ulink
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          url="http://www.openssh.com/portable.html">OpenSSH</ulink></simpara>
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        </listitem>
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        <listitem>
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          <simpara><ulink url="http://bridge.sourceforge.net/">Bridge
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          utilities</ulink></simpara>
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        </listitem>
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        <listitem>
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          <simpara><ulink
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          url="http://fping.sourceforge.net/">fping</ulink></simpara>
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        </listitem>
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        <listitem>
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          <simpara><ulink
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          url="http://developer.osdl.org/dev/iproute2">iproute2</ulink></simpara>
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        </listitem>
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        <listitem>
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          <simpara><ulink
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          url="ftp://ftp.inr.ac.ru/ip-routing/iputils-current.tar.gz">arping</ulink>
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          (part of iputils package)</simpara>
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        </listitem>
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        <listitem>
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          <simpara><ulink
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          url="http://www.kernel.org/pub/linux/utils/raid/mdadm/">mdadm</ulink>
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          (Linux Software Raid tools)</simpara>
396
        </listitem>
397
        <listitem>
398
          <simpara><ulink url="http://www.python.org">Python 2.4</ulink></simpara>
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        </listitem>
400
        <listitem>
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          <simpara><ulink url="http://twistedmatrix.com/">Python
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          Twisted library</ulink> - the core library is
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          enough</simpara>
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        </listitem>
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        <listitem>
406
          <simpara><ulink
407
          url="http://pyopenssl.sourceforge.net/">Python OpenSSL
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          bindings</ulink></simpara>
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        </listitem>
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      </itemizedlist>
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      <para>
413
        These programs are supplied as part of most Linux
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        distributions, so usually they can be installed via apt or
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        similar methods. Also many of them will already be installed
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        on a standard machine.
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      </para>
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420
      <formalpara><title>Debian</title>
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422
      <para>You can use this command line to install all of them:</para>
423

    
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      </formalpara>
425
      <screen>
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# apt-get install lvm2 ssh bridge-utils iproute iputils-arping \
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  fping python2.4 python-twisted-core python-pyopenssl openssl \
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  mdadm
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      </screen>
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    </sect2>
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433
  </sect1>
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  <sect1>
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    <title>Setting up the environment for Ganeti</title>
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439
    <sect2>
440
      <title>Configuring the network</title>
441

    
442
      <para><emphasis role="strong">Mandatory</emphasis> on all nodes.</para>
443

    
444
      <para>
445
        Ganeti relies on Xen running in "bridge mode", which means the
446
        instances network interfaces will be attached to a software bridge
447
        running in dom0. Xen by default creates such a bridge at startup, but
448
        your distribution might have a different way to do things.
449
      </para>
450

    
451
      <para>
452
        Beware that the default name Ganeti uses is
453
        <hardware>xen-br0</hardware> (which was used in Xen 2.0)
454
        while Xen 3.0 uses <hardware>xenbr0</hardware> by
455
        default. The default bridge your Ganeti cluster will use for new
456
        instances can be specified at cluster initialization time.
457
      </para>
458

    
459
      <formalpara><title>Debian</title>
460
        <para>
461
          The recommended Debian way to configure the Xen bridge is to
462
          edit your <filename>/etc/network/interfaces</filename> file
463
          and substitute your normal Ethernet stanza with the
464
          following snippet:
465

    
466
        <screen>
467
auto xen-br0
468
iface xen-br0 inet static
469
        address <replaceable>YOUR_IP_ADDRESS</replaceable>
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        netmask <replaceable>YOUR_NETMASK</replaceable>
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        network <replaceable>YOUR_NETWORK</replaceable>
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        broadcast <replaceable>YOUR_BROADCAST_ADDRESS</replaceable>
473
        gateway <replaceable>YOUR_GATEWAY</replaceable>
474
        bridge_ports eth0
475
        bridge_stp off
476
        bridge_fd 0
477
        </screen>
478
        </para>
479
      </formalpara>
480

    
481
     <para>
482
The following commands need to be executed on the local console
483
     </para>
484
      <screen>
485
ifdown eth0
486
ifup xen-br0
487
      </screen>
488

    
489
      <para>
490
        To check if the bridge is setup, use <command>ip</command>
491
        and <command>brctl show</command>:
492
      <para>
493

    
494
      <screen>
495
# ip a show xen-br0
496
9: xen-br0: &lt;BROADCAST,MULTICAST,UP,10000&gt; mtu 1500 qdisc noqueue
497
    link/ether 00:20:fc:1e:d5:5d brd ff:ff:ff:ff:ff:ff
498
    inet 10.1.1.200/24 brd 10.1.1.255 scope global xen-br0
499
    inet6 fe80::220:fcff:fe1e:d55d/64 scope link
500
       valid_lft forever preferred_lft forever
501

    
502
# brctl show xen-br0
503
bridge name     bridge id               STP enabled     interfaces
504
xen-br0         8000.0020fc1ed55d       no              eth0
505
      </screen>
506

    
507

    
508
    </sect2>
509

    
510
    <sect2>
511
      <title>Configuring LVM</title>
512

    
513

    
514
      <para><emphasis role="strong">Mandatory</emphasis> on all nodes.</para>
515

    
516
      <note>
517
        <simpara>The volume group is required to be at least
518
        <constant>20GiB</constant>.</simpara>
519
      </note>
520
      <para>
521
        If you haven't configured your LVM volume group at install
522
        time you need to do it before trying to initialize the Ganeti
523
        cluster. This is done by formatting the devices/partitions you
524
        want to use for it and then adding them to the relevant volume
525
        group:
526

    
527
       <screen>
528
pvcreate /dev/sda3
529
vgcreate xenvg /dev/sda3
530
       </screen>
531
or
532
       <screen>
533
pvcreate /dev/sdb1
534
pvcreate /dev/sdc1
535
vgcreate xenvg /dev/sdb1 /dev/sdc1
536
       </screen>
537
      </para>
538

    
539
      <para>
540
	If you want to add a device later you can do so with the
541
	<citerefentry><refentrytitle>vgextend</refentrytitle>
542
	<manvolnum>8</manvolnum></citerefentry> command:
543
      </para>
544

    
545
      <screen>
546
pvcreate /dev/sdd1
547
vgextend xenvg /dev/sdd1
548
      </screen>
549

    
550
      <formalpara>
551
        <title>Optional</title>
552
        <para>
553
          It is recommended to configure LVM not to scan the DRBD
554
          devices for physical volumes. This can be accomplished by
555
          editing <filename>/etc/lvm/lvm.conf</filename> and adding
556
          the <literal>/dev/drbd[0-9]+</literal> regular expression to
557
          the <literal>filter</literal> variable, like this:
558
<screen>
559
    filter = [ "r|/dev/cdrom|", "r|/dev/drbd[0-9]+|" ]
560
</screen>
561
        </para>
562
      </formalpara>
563

    
564
    </sect2>
565

    
566
    <sect2>
567
      <title>Installing Ganeti</title>
568

    
569
      <para><emphasis role="strong">Mandatory</emphasis> on all nodes.</para>
570

    
571
      <para>
572
        It's now time to install the Ganeti software itself.  Download
573
        the source from <ulink
574
        url="http://code.google.com/p/ganeti/"></ulink>.
575
      </para>
576

    
577
        <screen>
578
tar xvzf ganeti-1.2b1.tar.gz
579
cd ganeti-1.2b1
580
./configure --localstatedir=/var
581
make
582
make install
583
mkdir /srv/ganeti/ /srv/ganeti/os /srv/ganeti/export
584
        </screen>
585

    
586
      <para>
587
        You also need to copy the file
588
        <filename>docs/examples/ganeti.initd</filename>
589
        from the source archive to
590
        <filename>/etc/init.d/ganeti</filename> and register it with
591
        your distribution's startup scripts, for example in Debian:
592
      </para>
593
      <screen>update-rc.d ganeti defaults 20 80</screen>
594

    
595
      <para>
596
        In order to automatically restart failed instances, you need
597
        to setup a cron job run the
598
        <computeroutput>ganeti-watcher</computeroutput> program. A
599
        sample cron file is provided in the source at
600
        <filename>docs/examples/ganeti.cron</filename> and you can
601
        copy that (eventually altering the path) to
602
        <filename>/etc/cron.d/ganeti</filename>
603
      </para>
604

    
605
    </sect2>
606

    
607
    <sect2>
608
      <title>Installing the Operating System support packages</title>
609

    
610
      <para><emphasis role="strong">Mandatory</emphasis> on all nodes.</para>
611

    
612
      <para>
613
        To be able to install instances you need to have an Operating
614
        System installation script. An example for Debian Etch is
615
        provided on the project web site.  Download it from <ulink
616
        url="http://code.google.com/p/ganeti/"></ulink> and follow the
617
        instructions in the <filename>README</filename> file.  Here is
618
        the installation procedure:
619
      </para>
620

    
621
      <screen>
622
cd /srv/ganeti/os
623
tar xvf instance-debian-etch-0.1.tar
624
mv instance-debian-etch-0.1 debian-etch
625
      </screen>
626

    
627
      <para>
628
        In order to use this OS definition, you need to have internet
629
        access from your nodes and have <citerefentry>
630
        <refentrytitle>debootstrap</refentrytitle>
631
        <manvolnum>8</manvolnum> </citerefentry> installed on all the
632
        nodes.
633
      </para>
634
      <formalpara>
635
        <title>Debian</title>
636
        <para>
637
          Use this command on all nodes to install
638
          <computeroutput>debootstrap</computeroutput>:
639

    
640
          <screen>apt-get install debootstrap</screen>
641
        </para>
642
      </formalpara>
643

    
644
      <para>
645
        Alternatively, you can create your own OS definitions. See the
646
        manpage
647
        <citerefentry>
648
        <refentrytitle>ganeti-os-interface</refentrytitle>
649
        <manvolnum>8</manvolnum>
650
        </citerefentry>.
651
      </para>
652

    
653
    </sect2>
654

    
655
    <sect2>
656
      <title>Initializing the cluster</title>
657

    
658
      <para><emphasis role="strong">Mandatory:</emphasis> only on one
659
      node per cluster.</para>
660

    
661

    
662
      <para>The last step is to initialize the cluster. After you've repeated
663
        the above process on all of your nodes, choose one as the master, and execute:
664
      </para>
665

    
666
      <screen>
667
gnt-cluster init <replaceable>CLUSTERNAME</replaceable>
668
      </screen>
669

    
670
      <para>
671
        The <replaceable>CLUSTERNAME</replaceable> is a hostname,
672
        which must be resolvable (e.g. it must exist in DNS or in
673
        <filename>/etc/hosts</filename>) by all the nodes in the
674
        cluster. You must choose a name different from any of the
675
        nodes names for a multi-node cluster. In general the best
676
        choice is to have a unique name for a cluster, even if it
677
        consists of only one machine, as you will be able to expand it
678
        later without any problems.
679
      </para>
680

    
681
      <para>
682
        If the bridge name you are using is not
683
        <literal>xen-br0</literal>, use the <option>-b
684
        <replaceable>BRIDGENAME</replaceable></option> option to
685
        specify the bridge name. In this case, you should also use the
686
        <option>--master-netdev
687
        <replaceable>BRIDGENAME</replaceable></option> option with the
688
        same <replaceable>BRIDGENAME</replaceable> argument.
689
      </para>
690

    
691
      <para>
692
        You can use a different name than <literal>xenvg</literal> for
693
        the volume group (but note that the name must be identical on
694
        all nodes). In this case you need to specify it by passing the
695
        <option>-g <replaceable>VGNAME</replaceable></option> option
696
        to <computeroutput>gnt-cluster init</computeroutput>.
697
      </para>
698

    
699
      <para>
700
        You can also invoke the command with the
701
        <option>--help</option> option in order to see all the
702
        possibilities.
703
      </para>
704

    
705
    </sect2>
706

    
707
    <sect2>
708
      <title>Joining the nodes to the cluster</title>
709

    
710
      <para>
711
        <emphasis role="strong">Mandatory:</emphasis> for all the
712
        other nodes.
713
      </para>
714

    
715
      <para>
716
        After you have initialized your cluster you need to join the
717
        other nodes to it. You can do so by executing the following
718
        command on the master node:
719
      </para>
720
        <screen>
721
gnt-node add <replaceable>NODENAME</replaceable>
722
        </screen>
723
    </sect2>
724

    
725
    <sect2>
726
      <title>Separate replication network</title>
727

    
728
      <para><emphasis role="strong">Optional</emphasis></para>
729
      <para>
730
        Ganeti uses DRBD to mirror the disk of the virtual instances
731
        between nodes. To use a dedicated network interface for this
732
        (in order to improve performance or to enhance security) you
733
        need to configure an additional interface for each node.  Use
734
        the <option>-s</option> option with
735
        <computeroutput>gnt-cluster init</computeroutput> and
736
        <computeroutput>gnt-node add</computeroutput> to specify the
737
        IP address of this secondary interface to use for each
738
        node. Note that if you specified this option at cluster setup
739
        time, you must afterwards use it for every node add operation.
740
      </para>
741
    </sect2>
742

    
743
    <sect2>
744
      <title>Testing the setup</title>
745

    
746
      <para>
747

    
748
        Execute the <computeroutput>gnt-node list</computeroutput>
749
        command to see all nodes in the cluster:
750
      <screen>
751
# gnt-node list
752
Node              DTotal  DFree MTotal MNode MFree Pinst Sinst
753
node1.example.com 197404 197404   2047  1896   125     0     0
754
      </screen>
755
    </para>
756
  </sect2>
757

    
758
  <sect1>
759
    <title>Setting up and managing virtual instances</title>
760
    <sect2>
761
      <title>Setting up virtual instances</title>
762
      <para>
763
        This step shows how to setup a virtual instance with either
764
        non-mirrored disks (<computeroutput>plain</computeroutput>) or
765
        with network mirrored disks
766
        (<computeroutput>remote_raid1</computeroutput>).  All commands
767
        need to be executed on the Ganeti master node (the one on
768
        which <computeroutput>gnt-cluster init</computeroutput> was
769
        run).  Verify that the OS scripts are present on all cluster
770
        nodes with <computeroutput>gnt-os list</computeroutput>.
771
      </para>
772
      <para>
773
        To create a virtual instance, you need a hostname which is
774
        resolvable (DNS or <filename>/etc/hosts</filename> on all
775
        nodes). The following command will create a non-mirrored
776
        instance for you:
777
      </para>
778
      <screen>
779
gnt-instance add --node=node1 -o debian-etch -t plain inst1.example.com
780
* creating instance disks...
781
adding instance inst1.example.com to cluster config
782
Waiting for instance inst1.example.com to sync disks.
783
Instance inst1.example.com's disks are in sync.
784
creating os for instance inst1.example.com on node node1.example.com
785
* running the instance OS create scripts...
786
      </screen>
787

    
788
      <para>
789
        The above instance will have no network interface enabled.
790
        You can access it over the virtual console with
791
        <computeroutput>gnt-instance console
792
        <literal>inst1</literal></computeroutput>. There is no
793
        password for root.  As this is a Debian instance, you can
794
        modify the <filename>/etc/network/interfaces</filename> file
795
        to setup the network interface (<literal>eth0</literal> is the
796
        name of the interface provided to the instance).
797
      </para>
798

    
799
      <para>
800
        To create a network mirrored instance, change the argument to
801
        the <option>-t</option> option from <literal>plain</literal>
802
        to <literal>remote_raid1</literal> and specify the node on
803
        which the mirror should reside with the
804
        <option>--secondary-node</option> option, like this:
805
      </para>
806

    
807
      <screen>
808
# gnt-instance add -t remote_raid1 --secondary-node node1 \
809
  -n node2 -o debian-etch instance2
810
* creating instance disks...
811
adding instance instance2 to cluster config
812
Waiting for instance instance1 to sync disks.
813
- device sdb:  3.50% done, 304 estimated seconds remaining
814
- device sdb: 21.70% done, 270 estimated seconds remaining
815
- device sdb: 39.80% done, 247 estimated seconds remaining
816
- device sdb: 58.10% done, 121 estimated seconds remaining
817
- device sdb: 76.30% done, 72 estimated seconds remaining
818
- device sdb: 94.80% done, 18 estimated seconds remaining
819
Instance instance2's disks are in sync.
820
creating os for instance instance2 on node node2.example.com
821
* running the instance OS create scripts...
822
* starting instance...
823
      </screen>
824

    
825
    </sect2>
826

    
827
    <sect2>
828
      <title>Managing virtual instances</title>
829
      <para>
830
        All commands need to be executed on the Ganeti master node
831
      </para>
832

    
833
      <para>
834
        To access the console of an instance, use
835
        <computeroutput>gnt-instance console
836
        <replaceable>INSTANCENAME</replaceable></computeroutput>.
837
      </para>
838

    
839
      <para>
840
        To shutdown an instance, use <computeroutput>gnt-instance
841
        shutdown
842
        <replaceable>INSTANCENAME</replaceable></computeroutput>. To
843
        startup an instance, use <computeroutput>gnt-instance startup
844
        <replaceable>INSTANCENAME</replaceable></computeroutput>.
845
      </para>
846

    
847
      <para>
848
        To failover an instance to its secondary node (only possible
849
        in <literal>remote_raid1</literal> setup), use
850
        <computeroutput>gnt-instance failover
851
        <replaceable>INSTANCENAME</replaceable></computeroutput>.
852
      </para>
853

    
854
      <para>
855
        For more instance and cluster administration details, see the
856
        <emphasis>Ganeti administrator's guide</emphasis>.
857
      </para>
858

    
859
    </sect2>
860

    
861
  </sect1>
862

    
863
  </article>