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Ganeti installation tutorial
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============================
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Documents Ganeti version |version|
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.. contents::
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.. highlight:: shell-example
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Introduction
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------------
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Ganeti is a cluster virtualization management system based on Xen or
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KVM. This document explains how to bootstrap a Ganeti node (Xen *dom0*,
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the host Linux system for KVM), create a running cluster and install
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virtual instances (Xen *domUs*, KVM guests).  You need to repeat most of
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the steps in this document for every node you want to install, but of
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course we recommend creating some semi-automatic procedure if you plan
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to deploy Ganeti on a medium/large scale.
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A basic Ganeti terminology glossary is provided in the introductory
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section of the :doc:`admin`. Please refer to that document if you are
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uncertain about the terms we are using.
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Ganeti has been developed for Linux and should be distribution-agnostic.
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This documentation will use Debian Squeeze as an example system but the
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examples can be translated to any other distribution. You are expected
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to be familiar with your distribution, its package management system,
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and Xen or KVM before trying to use Ganeti.
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This document is divided into two main sections:
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- Installation of the base system and base components
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- Configuration of the environment for Ganeti
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Each of these is divided into sub-sections. While a full Ganeti system
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will need all of the steps specified, some are not strictly required for
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every environment. Which ones they are, and why, is specified in the
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corresponding sections.
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Installing the base system and base components
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----------------------------------------------
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Hardware requirements
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+++++++++++++++++++++
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Any system supported by your Linux distribution is fine. 64-bit systems
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are better as they can support more memory.
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Any disk drive recognized by Linux (``IDE``/``SCSI``/``SATA``/etc.) is
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supported in Ganeti. Note that no shared storage (e.g. ``SAN``) is
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needed to get high-availability features (but of course, one can be used
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to store the images). Whilte it is highly recommended to use more than
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one disk drive in order to improve speed, Ganeti also works with one
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disk per machine.
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Installing the base system
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++++++++++++++++++++++++++
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**Mandatory** on all nodes.
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It is advised to start with a clean, minimal install of the operating
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system. The only requirement you need to be aware of at this stage is to
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partition leaving enough space for a big (**minimum** 20GiB) LVM volume
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group which will then host your instance filesystems, if you want to use
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all Ganeti features. The volume group name Ganeti uses (by default) is
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``xenvg``.
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You can also use file-based storage only, without LVM, but this setup is
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not detailed in this document.
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If you choose to use RBD-based instances, there's no need for LVM
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provisioning. However, this feature is experimental, and is not yet
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recommended for production clusters.
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While you can use an existing system, please note that the Ganeti
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installation is intrusive in terms of changes to the system
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configuration, and it's best to use a newly-installed system without
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important data on it.
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Also, for best results, it's advised that the nodes have as much as
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possible the same hardware and software configuration. This will make
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administration much easier.
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Hostname issues
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~~~~~~~~~~~~~~~
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Note that Ganeti requires the hostnames of the systems (i.e. what the
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``hostname`` command outputs to be a fully-qualified name, not a short
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name. In other words, you should use *node1.example.com* as a hostname
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and not just *node1*.
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.. admonition:: Debian
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   Debian usually configures the hostname differently than you need it
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   for Ganeti. For example, this is what it puts in ``/etc/hosts`` in
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   certain situations::
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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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   but for Ganeti you need to have::
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     127.0.0.1       localhost
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     192.0.2.1       node1.example.com node1
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   replacing ``192.0.2.1`` with your node's address. Also, the file
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   ``/etc/hostname`` which configures the hostname of the system
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   should contain ``node1.example.com`` and not just ``node1`` (you
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   need to run the command ``/etc/init.d/hostname.sh start`` after
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   changing the file).
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.. admonition:: Why a fully qualified host name
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   Although most distributions use only the short name in the
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   /etc/hostname file, we still think Ganeti nodes should use the full
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   name. The reason for this is that calling 'hostname --fqdn' requires
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   the resolver library to work and is a 'guess' via heuristics at what
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   is your domain name. Since Ganeti can be used among other things to
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   host DNS servers, we don't want to depend on them as much as
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   possible, and we'd rather have the uname() syscall return the full
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   node name.
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   We haven't ever found any breakage in using a full hostname on a
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   Linux system, and anyway we recommend to have only a minimal
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   installation on Ganeti nodes, and to use instances (or other
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   dedicated machines) to run the rest of your network services. By
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   doing this you can change the /etc/hostname file to contain an FQDN
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   without the fear of breaking anything unrelated.
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Installing The Hypervisor
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+++++++++++++++++++++++++
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**Mandatory** on all nodes.
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While Ganeti is developed with the ability to modularly run on different
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virtualization environments in mind the only two currently useable on a
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live system are Xen and KVM. Supported Xen versions are: 3.0.3 and later
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3.x versions, and 4.x (tested up to 4.1).  Supported KVM versions are 72
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and above.
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Please follow your distribution's recommended way to install and set up
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Xen, or install Xen from the upstream source, if you wish, following
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their manual. For KVM, make sure you have a KVM-enabled kernel and the
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KVM tools.
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After installing Xen, you need to reboot into your new system. On some
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distributions this might involve configuring GRUB appropriately, whereas
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others will configure it automatically when you install the respective
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kernels. For KVM no reboot should be necessary.
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.. admonition:: Xen on Debian
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   Under Debian you can install the relevant ``xen-linux-system``
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   package, which will pull in both the hypervisor and the relevant
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   kernel. Also, if you are installing a 32-bit system, you should
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   install the ``libc6-xen`` package (run ``apt-get install
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   libc6-xen``).
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Xen settings
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~~~~~~~~~~~~
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It's recommended that dom0 is restricted to a low amount of memory
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(512MiB or 1GiB is reasonable) and that memory ballooning is disabled in
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the file ``/etc/xen/xend-config.sxp`` by setting the value
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``dom0-min-mem`` to 0, like this::
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  (dom0-min-mem 0)
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For optimum performance when running both CPU and I/O intensive
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instances, it's also recommended that the dom0 is restricted to one CPU
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only, for example by booting with the kernel parameter ``maxcpus=1``.
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It is recommended that you disable xen's automatic save of virtual
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machines at system shutdown and subsequent restore of them at reboot.
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To obtain this make sure the variable ``XENDOMAINS_SAVE`` in the file
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``/etc/default/xendomains`` is set to an empty value.
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If you want to use live migration make sure you have, in the xen config
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file, something that allows the nodes to migrate instances between each
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other. For example:
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.. code-block:: text
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  (xend-relocation-server yes)
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  (xend-relocation-port 8002)
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  (xend-relocation-address '')
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  (xend-relocation-hosts-allow '^192\\.0\\.2\\.[0-9]+$')
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The second line assumes that the hypervisor parameter
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``migration_port`` is set 8002, otherwise modify it to match. The last
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line assumes that all your nodes have secondary IPs in the
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192.0.2.0/24 network, adjust it accordingly to your setup.
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.. admonition:: Debian
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   Besides the ballooning change which you need to set in
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   ``/etc/xen/xend-config.sxp``, you need to set the memory and nosmp
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   parameters in the file ``/boot/grub/menu.lst``. You need to modify
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   the variable ``xenhopt`` to add ``dom0_mem=1024M`` like this:
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   .. code-block:: text
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     ## Xen hypervisor options to use with the default Xen boot option
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     # xenhopt=dom0_mem=1024M
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   and the ``xenkopt`` needs to include the ``maxcpus`` option like
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   this:
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   .. code-block:: text
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     ## Xen Linux kernel options to use with the default Xen boot option
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     # xenkopt=maxcpus=1
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   Any existing parameters can be left in place: it's ok to have
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   ``xenkopt=console=tty0 maxcpus=1``, for example. After modifying the
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   files, you need to run::
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     $ /sbin/update-grub
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If you want to run HVM instances too with Ganeti and want VNC access to
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the console of your instances, set the following two entries in
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``/etc/xen/xend-config.sxp``:
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.. code-block:: text
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  (vnc-listen '0.0.0.0') (vncpasswd '')
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You need to restart the Xen daemon for these settings to take effect::
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  $ /etc/init.d/xend restart
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Selecting the instance kernel
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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After you have installed Xen, you need to tell Ganeti exactly what
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kernel to use for the instances it will create. This is done by creating
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a symlink from your actual kernel to ``/boot/vmlinuz-3-xenU``, and one
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from your initrd to ``/boot/initrd-3-xenU`` [#defkernel]_. Note that
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if you don't use an initrd for the domU kernel, you don't need to create
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the initrd symlink.
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.. admonition:: Debian
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   After installation of the ``xen-linux-system`` package, you need to
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   run (replace the exact version number with the one you have)::
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     $ cd /boot
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     $ ln -s vmlinuz-%2.6.26-1%-xen-amd64 vmlinuz-3-xenU
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     $ ln -s initrd.img-%2.6.26-1%-xen-amd64 initrd-3-xenU
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   By default, the initrd doesn't contain the Xen block drivers needed
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   to mount the root device, so it is recommended to update the initrd
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   by following these two steps:
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   - edit ``/etc/initramfs-tools/modules`` and add ``xen_blkfront``
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   - run ``update-initramfs -u``
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Installing DRBD
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+++++++++++++++
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Recommended on all nodes: DRBD_ is required if you want to use the high
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availability (HA) features of Ganeti, but optional if you don't require
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them or only run Ganeti on single-node clusters. You can upgrade a
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non-HA cluster to an HA one later, but you might need to convert all
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your instances to DRBD to take advantage of the new features.
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.. _DRBD: http://www.drbd.org/
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Supported DRBD versions: 8.0-8.3. It's recommended to have at least
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version 8.0.12. Note that for version 8.2 and newer it is needed to pass
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the ``usermode_helper=/bin/true`` parameter to the module, either by
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configuring ``/etc/modules`` or when inserting it manually.
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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 anyway fiddling
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with it. Hopefully at least the Xen-ified kernel source to start from
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will be provided (if you intend to use Xen).
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The good news is that you don't need to configure DRBD at all. Ganeti
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will do it for you for every instance you set up.  If you have the DRBD
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utils installed and the module in your kernel you're fine. Please check
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that your system is configured to load the module at every boot, and
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that it passes the following option to the module:
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``minor_count=NUMBER``. We recommend that you use 128 as the value of
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the minor_count - this will allow you to use up to 64 instances in total
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per node (both primary and secondary, when using only one disk per
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instance). You can increase the number up to 255 if you need more
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instances on a node.
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.. admonition:: Debian
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   On Debian, you can just install (build) the DRBD module with the
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   following commands, making sure you are running the target (Xen or
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   KVM) kernel::
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     $ apt-get install drbd8-source drbd8-utils
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     $ m-a update
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     $ m-a a-i drbd8
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     $ echo drbd minor_count=128 usermode_helper=/bin/true >> /etc/modules
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     $ depmod -a
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     $ modprobe drbd minor_count=128 usermode_helper=/bin/true
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   It is also recommended that you comment out the default resources in
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   the ``/etc/drbd.conf`` file, so that the init script doesn't try to
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   configure any drbd devices. You can do this by prefixing all
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   *resource* lines in the file with the keyword *skip*, like this:
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   .. code-block:: text
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     skip {
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       resource r0 {
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         ...
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       }
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     }
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     skip {
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       resource "r1" {
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         ...
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       }
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     }
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Installing RBD
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++++++++++++++
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Recommended on all nodes: RBD_ is required if you want to create
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instances with RBD disks residing inside a RADOS cluster (make use of
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the rbd disk template). RBD-based instances can failover or migrate to
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any other node in the ganeti cluster, enabling you to exploit of all
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Ganeti's high availabilily (HA) features.
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.. attention::
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   Be careful though: rbd is still experimental! For now it is
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   recommended only for testing purposes.  No sensitive data should be
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   stored there.
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.. _RBD: http://ceph.newdream.net/
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You will need the ``rbd`` and ``libceph`` kernel modules, the RBD/Ceph
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userspace utils (ceph-common Debian package) and an appropriate
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Ceph/RADOS configuration file on every VM-capable node.
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You will also need a working RADOS Cluster accessible by the above
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nodes.
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RADOS Cluster
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~~~~~~~~~~~~~
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You will need a working RADOS Cluster accesible by all VM-capable nodes
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to use the RBD template. For more information on setting up a RADOS
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Cluster, refer to the `official docs <http://ceph.newdream.net/>`_.
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If you want to use a pool for storing RBD disk images other than the
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default (``rbd``), you should first create the pool in the RADOS
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Cluster, and then set the corresponding rbd disk parameter named
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``pool``.
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Kernel Modules
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~~~~~~~~~~~~~~
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Unless your distribution already provides it, you might need to compile
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the ``rbd`` and ``libceph`` modules from source. You will need Linux
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Kernel 3.2 or above for the kernel modules. Alternatively you will have
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to build them as external modules (from Linux Kernel source 3.2 or
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above), if you want to run a less recent kernel, or your kernel doesn't
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include them.
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Userspace Utils
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~~~~~~~~~~~~~~~
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The RBD template has been tested with ``ceph-common`` v0.38 and
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above. We recommend using the latest version of ``ceph-common``.
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.. admonition:: Debian
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   On Debian, you can just install the RBD/Ceph userspace utils with
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   the following command::
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      $ apt-get install ceph-common
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Configuration file
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~~~~~~~~~~~~~~~~~~
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You should also provide an appropriate configuration file
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(``ceph.conf``) in ``/etc/ceph``. For the rbd userspace utils, you'll
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only need to specify the IP addresses of the RADOS Cluster monitors.
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.. admonition:: ceph.conf
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   Sample configuration file:
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   .. code-block:: text
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    [mon.a]
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           host = example_monitor_host1
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           mon addr = 1.2.3.4:6789
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    [mon.b]
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           host = example_monitor_host2
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           mon addr = 1.2.3.5:6789
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    [mon.c]
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           host = example_monitor_host3
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           mon addr = 1.2.3.6:6789
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For more information, please see the `Ceph Docs
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<http://ceph.newdream.net/docs/latest/>`_
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Other required software
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+++++++++++++++++++++++
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See :doc:`install-quick`.
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Setting up the environment for Ganeti
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-------------------------------------
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Configuring the network
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+++++++++++++++++++++++
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**Mandatory** on all nodes.
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You can run Ganeti either in "bridged mode" or in "routed mode". In
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bridged mode, the default, the instances network interfaces will be
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attached to a software bridge running in dom0. Xen by default creates
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such a bridge at startup, but your distribution might have a different
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way to do things, and you'll definitely need to manually set it up under
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KVM.
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Beware that the default name Ganeti uses is ``xen-br0`` (which was used
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in Xen 2.0) while Xen 3.0 uses ``xenbr0`` by default. See the
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`Initializing the cluster`_ section to learn how to choose a different
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bridge, or not to use one at all and use "routed mode".
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In order to use "routed mode" under Xen, you'll need to change the
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relevant parameters in the Xen config file. Under KVM instead, no config
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change is necessary, but you still need to set up your network
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interfaces correctly.
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By default, under KVM, the "link" parameter you specify per-nic will
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represent, if non-empty, a different routing table name or number to use
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for your instances. This allows isolation between different instance
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groups, and different routing policies between node traffic and instance
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traffic.
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You will need to configure your routing table basic routes and rules
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outside of ganeti. The vif scripts will only add /32 routes to your
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instances, through their interface, in the table you specified (under
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KVM, and in the main table under Xen).
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.. admonition:: Bridging under Debian
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   The recommended way to configure the Xen bridge is to edit your
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   ``/etc/network/interfaces`` file and substitute your normal
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   Ethernet stanza with the following snippet::
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     auto xen-br0
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     iface xen-br0 inet static
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        address %YOUR_IP_ADDRESS%
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        netmask %YOUR_NETMASK%
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        network %YOUR_NETWORK%
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        broadcast %YOUR_BROADCAST_ADDRESS%
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        gateway %YOUR_GATEWAY%
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        bridge_ports eth0
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        bridge_stp off
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        bridge_fd 0
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The following commands need to be executed on the local console::
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471
  $ ifdown eth0
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  $ ifup xen-br0
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To check if the bridge is setup, use the ``ip`` and ``brctl show``
475
commands::
476

    
477
  $ ip a show xen-br0
478
  9: xen-br0: <BROADCAST,MULTICAST,UP,10000> mtu 1500 qdisc noqueue
479
      link/ether 00:20:fc:1e:d5:5d brd ff:ff:ff:ff:ff:ff
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      inet 10.1.1.200/24 brd 10.1.1.255 scope global xen-br0
481
      inet6 fe80::220:fcff:fe1e:d55d/64 scope link
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         valid_lft forever preferred_lft forever
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484
  $ brctl show xen-br0
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  bridge name     bridge id               STP enabled     interfaces
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  xen-br0         8000.0020fc1ed55d       no              eth0
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.. _configure-lvm-label:
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Configuring LVM
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+++++++++++++++
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493
**Mandatory** on all nodes.
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495
The volume group is required to be at least 20GiB.
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If you haven't configured your LVM volume group at install time you need
498
to do it before trying to initialize the Ganeti cluster. This is done by
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formatting the devices/partitions you want to use for it and then adding
500
them to the relevant volume group::
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502
  $ pvcreate /dev/%sda3%
503
  $ vgcreate xenvg /dev/%sda3%
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505
or::
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507
  $ pvcreate /dev/%sdb1%
508
  $ pvcreate /dev/%sdc1%
509
  $ vgcreate xenvg /dev/%sdb1% /dev/%sdc1%
510

    
511
If you want to add a device later you can do so with the *vgextend*
512
command::
513

    
514
  $ pvcreate /dev/%sdd1%
515
  $ vgextend xenvg /dev/%sdd1%
516

    
517
Optional: it is recommended to configure LVM not to scan the DRBD
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devices for physical volumes. This can be accomplished by editing
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``/etc/lvm/lvm.conf`` and adding the ``/dev/drbd[0-9]+`` regular
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expression to the ``filter`` variable, like this:
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.. code-block:: text
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  filter = ["r|/dev/cdrom|", "r|/dev/drbd[0-9]+|" ]
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Note that with Ganeti a helper script is provided - ``lvmstrap`` which
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will erase and configure as LVM any not in-use disk on your system. This
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is dangerous and it's recommended to read its ``--help`` output if you
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want to use it.
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531
Installing Ganeti
532
+++++++++++++++++
533

    
534
**Mandatory** on all nodes.
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536
It's now time to install the Ganeti software itself.  Download the
537
source from the project page at `<http://code.google.com/p/ganeti/>`_,
538
and install it (replace 2.6.0 with the latest version)::
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  $ tar xvzf ganeti-%2.6.0%.tar.gz
541
  $ cd ganeti-%2.6.0%
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  $ ./configure --localstatedir=/var --sysconfdir=/etc
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  $ make
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  $ make install
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  $ mkdir /srv/ganeti/ /srv/ganeti/os /srv/ganeti/export
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You also need to copy the file ``doc/examples/ganeti.initd`` from the
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source archive to ``/etc/init.d/ganeti`` and register it with your
549
distribution's startup scripts, for example in Debian::
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551
  $ update-rc.d ganeti defaults 20 80
552

    
553
In order to automatically restart failed instances, you need to setup a
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cron job run the *ganeti-watcher* command. A sample cron file is
555
provided in the source at ``doc/examples/ganeti.cron`` and you can copy
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that (eventually altering the path) to ``/etc/cron.d/ganeti``.
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What gets installed
559
~~~~~~~~~~~~~~~~~~~
560

    
561
The above ``make install`` invocation, or installing via your
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distribution mechanisms, will install on the system:
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- a set of python libraries under the *ganeti* namespace (depending on
565
  the python version this can be located in either
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  ``lib/python-$ver/site-packages`` or various other locations)
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- a set of programs under ``/usr/local/sbin`` or ``/usr/sbin``
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- if the htools component was enabled, a set of programs unde
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  ``/usr/local/bin`` or ``/usr/bin/``
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- man pages for the above programs
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- a set of tools under the ``lib/ganeti/tools`` directory
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- an example iallocator script (see the admin guide for details) under
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  ``lib/ganeti/iallocators``
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- a cron job that is needed for cluster maintenance
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- an init script for automatic startup of Ganeti daemons
576
- provided but not installed automatically by ``make install`` is a bash
577
  completion script that hopefully will ease working with the many
578
  cluster commands
579

    
580
Installing the Operating System support packages
581
++++++++++++++++++++++++++++++++++++++++++++++++
582

    
583
**Mandatory** on all nodes.
584

    
585
To be able to install instances you need to have an Operating System
586
installation script. An example OS that works under Debian and can
587
install Debian and Ubuntu instace OSes is provided on the project web
588
site.  Download it from the project page and follow the instructions in
589
the ``README`` file.  Here is the installation procedure (replace 0.9
590
with the latest version that is compatible with your ganeti version)::
591

    
592
  $ cd /usr/local/src/
593
  $ wget http://ganeti.googlecode.com/files/ganeti-instance-debootstrap-%0.9%.tar.gz
594
  $ tar xzf ganeti-instance-debootstrap-%0.9%.tar.gz
595
  $ cd ganeti-instance-debootstrap-%0.9%
596
  $ ./configure
597
  $ make
598
  $ make install
599

    
600
In order to use this OS definition, you need to have internet access
601
from your nodes and have the *debootstrap*, *dump* and *restore*
602
commands installed on all nodes. Also, if the OS is configured to
603
partition the instance's disk in
604
``/etc/default/ganeti-instance-debootstrap``, you will need *kpartx*
605
installed.
606

    
607
.. admonition:: Debian
608

    
609
   Use this command on all nodes to install the required packages::
610

    
611
     $ apt-get install debootstrap dump kpartx
612

    
613
   Or alternatively install the OS definition from the Debian package::
614

    
615
     $ apt-get install ganeti-instance-debootstrap
616

    
617
.. admonition:: KVM
618

    
619
   In order for debootstrap instances to be able to shutdown cleanly
620
   they must install have basic ACPI support inside the instance. Which
621
   packages are needed depend on the exact flavor of Debian or Ubuntu
622
   which you're installing, but the example defaults file has a
623
   commented out configuration line that works for Debian Lenny and
624
   Squeeze::
625

    
626
     EXTRA_PKGS="acpi-support-base,console-tools,udev"
627

    
628
   ``kbd`` can be used instead of ``console-tools``, and more packages
629
   can be added, of course, if needed.
630

    
631
Alternatively, you can create your own OS definitions. See the manpage
632
:manpage:`ganeti-os-interface`.
633

    
634
Initializing the cluster
635
++++++++++++++++++++++++
636

    
637
**Mandatory** once per cluster, on the first node.
638

    
639
The last step is to initialize the cluster. After you have repeated the
640
above process on all of your nodes, choose one as the master, and
641
execute::
642

    
643
  $ gnt-cluster init %CLUSTERNAME%
644

    
645
The *CLUSTERNAME* is a hostname, which must be resolvable (e.g. it must
646
exist in DNS or in ``/etc/hosts``) by all the nodes in the cluster. You
647
must choose a name different from any of the nodes names for a
648
multi-node cluster. In general the best choice is to have a unique name
649
for a cluster, even if it consists of only one machine, as you will be
650
able to expand it later without any problems. Please note that the
651
hostname used for this must resolve to an IP address reserved
652
**exclusively** for this purpose, and cannot be the name of the first
653
(master) node.
654

    
655
If you want to use a bridge which is not ``xen-br0``, or no bridge at
656
all, change it with the ``--nic-parameters`` option. For example to
657
bridge on br0 you can add::
658

    
659
  --nic-parameters link=br0
660

    
661
Or to not bridge at all, and use a separate routing table::
662

    
663
  --nic-parameters mode=routed,link=100
664

    
665
If you don't have a ``xen-br0`` interface you also have to specify a
666
different network interface which will get the cluster IP, on the master
667
node, by using the ``--master-netdev <device>`` option.
668

    
669
You can use a different name than ``xenvg`` for the volume group (but
670
note that the name must be identical on all nodes). In this case you
671
need to specify it by passing the *--vg-name <VGNAME>* option to
672
``gnt-cluster init``.
673

    
674
To set up the cluster as an Xen HVM cluster, use the
675
``--enabled-hypervisors=xen-hvm`` option to enable the HVM hypervisor
676
(you can also add ``,xen-pvm`` to enable the PVM one too). You will also
677
need to create the VNC cluster password file
678
``/etc/ganeti/vnc-cluster-password`` which contains one line with the
679
default VNC password for the cluster.
680

    
681
To setup the cluster for KVM-only usage (KVM and Xen cannot be mixed),
682
pass ``--enabled-hypervisors=kvm`` to the init command.
683

    
684
You can also invoke the command with the ``--help`` option in order to
685
see all the possibilities.
686

    
687
Hypervisor/Network/Cluster parameters
688
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
689

    
690
Please note that the default hypervisor/network/cluster parameters may
691
not be the correct one for your environment. Carefully check them, and
692
change them either at cluster init time, or later with ``gnt-cluster
693
modify``.
694

    
695
Your instance types, networking environment, hypervisor type and version
696
may all affect what kind of parameters should be used on your cluster.
697

    
698
For example kvm instances are by default configured to use a host
699
kernel, and to be reached via serial console, which works nice for Linux
700
paravirtualized instances. If you want fully virtualized instances you
701
may want to handle their kernel inside the instance, and to use VNC.
702

    
703
Joining the nodes to the cluster
704
++++++++++++++++++++++++++++++++
705

    
706
**Mandatory** for all the other nodes.
707

    
708
After you have initialized your cluster you need to join the other nodes
709
to it. You can do so by executing the following command on the master
710
node::
711

    
712
  $ gnt-node add %NODENAME%
713

    
714
Separate replication network
715
++++++++++++++++++++++++++++
716

    
717
**Optional**
718

    
719
Ganeti uses DRBD to mirror the disk of the virtual instances between
720
nodes. To use a dedicated network interface for this (in order to
721
improve performance or to enhance security) you need to configure an
722
additional interface for each node.  Use the *-s* option with
723
``gnt-cluster init`` and ``gnt-node add`` to specify the IP address of
724
this secondary interface to use for each node. Note that if you
725
specified this option at cluster setup time, you must afterwards use it
726
for every node add operation.
727

    
728
Testing the setup
729
+++++++++++++++++
730

    
731
Execute the ``gnt-node list`` command to see all nodes in the cluster::
732

    
733
  $ gnt-node list
734
  Node              DTotal  DFree MTotal MNode MFree Pinst Sinst
735
  node1.example.com 197404 197404   2047  1896   125     0     0
736

    
737
The above shows a couple of things:
738

    
739
- The various Ganeti daemons can talk to each other
740
- Ganeti can examine the storage of the node (DTotal/DFree)
741
- Ganeti can talk to the selected hypervisor (MTotal/MNode/MFree)
742

    
743
Cluster burnin
744
~~~~~~~~~~~~~~
745

    
746
With Ganeti a tool called :command:`burnin` is provided that can test
747
most of the Ganeti functionality. The tool is installed under the
748
``lib/ganeti/tools`` directory (either under ``/usr`` or ``/usr/local``
749
based on the installation method). See more details under
750
:ref:`burnin-label`.
751

    
752
Further steps
753
-------------
754

    
755
You can now proceed either to the :doc:`admin`, or read the manpages of
756
the various commands (:manpage:`ganeti(7)`, :manpage:`gnt-cluster(8)`,
757
:manpage:`gnt-node(8)`, :manpage:`gnt-instance(8)`,
758
:manpage:`gnt-job(8)`).
759

    
760
.. rubric:: Footnotes
761

    
762
.. [#defkernel] The kernel and initrd paths can be changed at either
763
   cluster level (which changes the default for all instances) or at
764
   instance level.
765

    
766
.. vim: set textwidth=72 :
767
.. Local Variables:
768
.. mode: rst
769
.. fill-column: 72
770
.. End: