Synnefo » snf-ganeti » ganeti-local

    <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.

          <simpara>Installation of the core system and base

          components</simpara>

          <simpara>Configuration of the environment for

          Ganeti</simpara>

    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>

      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>

      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><emphasis role="strong">Mandatory.</emphasis></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>

        <emphasis role="strong">Mandatory:</emphasis> 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>

        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>

        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>

        After installing Xen you need to reboot into your xenified

        dom0 system. Again on some distributions this might involve

        configuring GRUB appropriately.

      <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>

        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>

        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

        following commands should do it:

      </para>

      <screen>

      </screen>

      <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.

      In Debian, in order to enable the default Xen behaviour, you

      have to edit <filename>/etc/xen/xend-config.sxp</filename> and

      replace <computeroutput>(network-script

      network-dummy)</computeroutput> with

      <computeroutput>(network-script

      network-bridge)</computeroutput>. The recommended Debian way to

      configure things, though, is to edit your

      <filename>/etc/network/interfaces</filename> file and substitute

      your normal ethernet stanza with something like:</para>

      <screen>

        address <replaceable>YOUR_IP_ADDRESS</replaceable>

        netmask <replaceable>YOUR_NETMASK</replaceable>

        network <replaceable>YOUR_NETWORK</replaceable>

        broadcast <replaceable>YOUR_BROADCAST_ADDRESS</replaceable>

        gateway <replaceable>YOUR_GATEWAY</replaceable>

        bridge_ports <replaceable>eth0</replaceable>

      </screen>

      Beware that the default name Ganeti uses is

      <hardware>xen-br0</hardware> (which was used in Xen 2.0)

      while Xen 3.0 uses <hardware>xenbr0</hardware> by

      default. The default bridge your cluster will use for new

      instances can be specified at cluster initialization time.

        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:

       </para>

       <screen>

       </screen>

	If you want to add a device later you can do so with the

	<manvolnum>8</manvolnum></citerefentry> command:

      </para>

      <screen>

      </screen>

      <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 (note that the <option>localstatedir</option> options must

      be set to <filename class="directory">/var</filename>):

        <screen>

./configure --localstatedir=/var

        </screen>

        <screen>

        </screen>

        <screen>

        </screen>

      <para><emphasis role="strong">Mandatory:</emphasis> only on one

      node per cluster.</para>

      </para>

      <screen>

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

      </screen>

      <para>

        Options you can pass to <command>gnt-cluster init</command>

        include the default bridge name (<option>-b</option>), the

        cluster-wide name for the volume group (<option>-g</option>)

        and the secondary ip address for the initial node should you

        wish to keep the data replication network separate. Invoke it

        with <option>--help</option> to see all the possibilities.

      <para>

        Note that 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 unique name

        for a cluster, even if it consists of only one machine.

      <para>

        <emphasis role="strong">Mandatory:</emphasis> for all the

        other nodes.

        <screen>

gnt-node add <replaceable>NODENAME</replaceable>

        </screen>

        The only option is <option>-s</option>, which sets the node's

        secondary ip address for replication purposes, if you are

        using a separate replication network.

    <para>

      Now you can follow the admin guide to use your new Ganeti

      cluster.