[ganeti-local] / docs / installing.sgml

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  <article class="specification">
  <articleinfo>
    <title>Ganeti node/cluster installation tutorial</title>
  </articleinfo>
  <para>Documents Ganeti version 1.2</para>

  <sect1>
    <title>Introduction</title>

    <para>Ganeti is a cluster virtualization management system. This document
    explains how to bootstrap a Ganeti node and create a running cluster. You
    need to repeat most of the steps in this document for every node you want to
    install, but of course we recommend creating some semi-automatic procedure
    if you plan to deploy Ganeti on a medium/large scale.
    </para>

    <para>This document is divided into two main sections:

      <itemizedlist>
        <listitem>
          <simpara>Installation of the core system and base components</simpara>
        </listitem>
        <listitem>
          <simpara>Configuration of the environment for Ganeti</simpara>
        </listitem>
      </itemizedlist>

    Each of these is divided into sub-sections. While a full Ganeti system will
    need all of the steps specified, some are not strictly required for every
    environment. Which ones they are, and why, is specified in the
    corresponding sections.
    </para>

    <para>While Ganeti itself is distribution-agnostic most of the examples in
      this document will be targeted at Debian or debian derived distributions.
      You are expected to be familiar with your distribution, its package
      management system, and Xen before trying to use Ganeti.
    </para>

    <para>A basic Ganeti terminology glossary is provided in the introductory
      section of the "admin guide". Please refer to that if you are uncertain
      about the terms we are using.
    </para>

  </sect1>

  <sect1>
    <title>Installing the system and base components</title>

    <sect2>
      <title>Installing the base system</title>

      <para>Mandatory.
      </para>

      <para>Please install your operating system as you would normally do. The
        only requirement you need to be aware of at this stage is to partition
        leaving enough space for a big LVM volume group which will then host
        your instance file systems. You can even create the volume group at
        installation time, of course: the default volume group name Ganeti 1.2
        uses is "xenvg" but you may name it differently should you wish to, as
        long as the name is the same for all the nodes in the cluster.
      </para>

    </sect2>

    <sect2>
      <title>Installing Xen</title>

      <para>Mandatory: While Ganeti is developed with the ability to modularly
      run on different virtualization environments in mind the only one
      currently useable on a live system is Xen.
      </para>

      <para>Please follow your distribution's recommended way to install and set
      up Xen, or install Xen from the upstream source, if you wish, following
      their manual.
      </para>

      <para>For example under Debian 4.0 or 3.1+backports you can install the
      relevant xen-linux-system package, which will pull in both the hypervisor
      and the relevant kernel. On Ubuntu (from Gutsy on) the package is called
      ubuntu-xen-server.
      </para>

      <para>After installing Xen you need to reboot into your xenified dom0
      system. Again on some distributions this might involve configuring GRUB
      appropriately.
      </para>

    </sect2>

    <sect2>
      <title>Installing DRBD</title>

      <para>Recommended: DRBD is required if you want to use the high
        availability (HA) features of Ganeti, but optional if you don't require
        HA or only run Ganeti on single-node clusters. You can upgrade a non-HA
        cluster to an HA one later, but you might need to export and reimport
        all your instances to take advantage of the new features.
      </para>

      <para>Now the bad news: unless your distribution already provides it
      installing DRBD might involve recompiling your kernel or anyway fiddling
      with it. Hopefully at least the xenified kernel source to start from will
      be provided.
      </para>

      <para>Under Debian you can just install the drbd0.7-module-source and
      drbd0.7-utils packages, and your kernel source, and then run
      module-assistant to compile the drbd0.7 module. The commands:

      <programlisting>
m-a update
m-a a-i drbd0.7
      </programlisting>

      should do it for you.
      </para>

      <para>The good news is that you don't need to configure DRBD at all.
      Ganeti will do it for you for every instance you set up.  If you have the
      DRBD utils installed and the module in your kernel you're fine. Please
      check that your system is configured to load the module at every boot.
      </para>

    </sect2>

  </sect1>


  <sect1>
    <title>Setting up the environment for Ganeti</title>

    <sect2>
      <title>Configuring the network</title>

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

      <para>
      In Debian, in order to enable the default Xen behaviour, you have to edit
      /etc/xen/xend-config.sxp and replace (network-script network-dummy) with
      (network-script network-bridge). The recommended Debian way to configure
      things, though, is to edit your /etc/network/interfaces file and
      substitute your normal ethernet stanza with something like:

      <programlisting>
auto br0
iface br0 inet static
        address YOUR_IP_ADDRESS
        netmask YOUR_NETMASK
        network YOUR_NETWORK
        broadcast YOUR_BROADCAST_ADDRSS
        gateway YOUR_GATEWAY
        # dns-* options are implemented by the resolvconf package, if installed
        dns-nameservers YOUR_DNS_SERVERS
        dns-search YOUR_SEARCH_PATH
        bridge_ports eth0
        bridge_stp off
        bridge_fd 0
      </programlisting>

    </para>

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

    </sect2>

    <sect2>
      <title>Configuring LVM</title>

      <para>
        If you haven't configured your LVM volume group at install time you need
        to do it before trying to initialize the Ganeti cluster. This is done by
        formatting the devices/partitions you want to use for it and then adding
        them to the relevant volume group:

       <programlisting>
pvcreate /dev/sda4
pvcreate /dev/sdb
pvcreate /dev/sdc1
vgcreate xenvg /dev/sda4 /dev/sdb /dev/sdc1
       </programlisting>
      </para>

      <para>
        If you want to add a device later you can do so with the 
        <citerefentry><refentrytitle>vgextend</refentrytitle>
        <manvolnum>8</manvolnum></citerefentry> command.
        <programlisting>
pvcreate /dev/sdd
vgextend xenvg /dev/sdd
        </programlisting>
      </para>

      <para>
        As said before you may choose a different name for the volume group,
        as long as you stick to the same name on all the nodes of a cluster.
      </para>
    </sect2>

    <sect2>
      <title>Installing Ganeti</title>

      <para>It's now time to install the Ganeti software itself if you haven't
        done it yet. You can do it from source, with the usual steps:

        <programlisting>
./configure
make
make install
        </programlisting>

        or you can install the package relevant to your distribution, for
        example in Debian/Ubuntu:

        <programlisting>
dpkg -i ganeti_VERSION_all.deb
        </programlisting>

        or, if you have a source repository that holds the Ganeti software:

        <programlisting>
apt-get install ganeti
        </programlisting>
      </para>

    </sect2>

    <sect2>
      <title>Installing the Operating System support packages</title>

      <para>Another important component for Ganeti is the OS support packages,
        which let different operating systems be used as instances. You can
        install them by installing the relevant ganeti-instance-OS package.
      </para>

    </sect2>

    <sect2>
      <title>Initializing the cluster</title>

      <para>Mandatory: only on one node per cluster.
      </para>


      <para>The last step is to initialize the cluster. After you've repeated
        the above process or some semi-automatic form of it on all of your
        nodes choose one as the master, and execute:

        <programlisting>
gnt-cluster init CLUSTERNAME
        </programlisting>

        Options you can pass to gnt-cluster init include the default bridge
        name (-b), the cluster-wide name for the volume group (-g) and the
        secondary ip address for the initial node should you wish to keep the
        data replication network separate. Invoke it with --help to see all the
        possibilities.
      </para>

      <para>The cluster name must exist in DNS. You must choose a name
        different from any of the nodes names for a multi-node cluster. In
        general the best choice is to have a completely unique name for each
        cluster.
      </para>
    </sect2>

    <sect2>
      <title>Joining the nodes to the cluster.</title>

      <para>Mandatory: for all the other nodes.
      </para>

      <para>
        If you have already initialized your cluster you need to join the other
        nodes to it. You can do so by executing the following command on the
        master node:
        <programlisting>
gnt-node add NODENAME
        </programlisting>

        The only option is (-s), which sets the node's secondary ip address for
        replication purposes, if you are using a separate replication network.
      </para>
    </sect2>

  </sect1>

  <sect1>
    <title>This is it!</title>

    <para>Now you can follow the "admin guide" to use your new Ganeti cluster.
    </para>

  </sect1>


  </article>