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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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|
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Introduction |
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------------ |
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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 |
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*dom0*), create a running cluster and install virtual instance (Xen |
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*domU*). You need to repeat most of the steps in this document for |
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every node you want to install, but of course we recommend creating |
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some semi-automatic procedure if you plan to deploy Ganeti on a |
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medium/large scale. |
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|
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A basic Ganeti terminology glossary is provided in the introductory |
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section of the *Ganeti administrator's guide*. Please refer to that |
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document if you are uncertain about the terms we are using. |
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|
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Ganeti has been developed for Linux and is distribution-agnostic. |
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This documentation will use Debian Lenny as an example system but the |
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examples can easily be translated to any other distribution. ou are |
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expected to be familiar with your distribution, its package management |
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system, and Xen or KVM before trying to use Ganeti. |
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|
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This document is divided into two main sections: |
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|
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- Installation of the base system and base components |
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|
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- Configuration of the environment for Ganeti |
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|
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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 |
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for every environment. Which ones they are, and why, is specified in |
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the corresponding sections. |
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|
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Installing the base system and base components |
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---------------------------------------------- |
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|
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Hardware requirements |
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+++++++++++++++++++++ |
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|
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Any system supported by your Linux distribution is fine. 64-bit |
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systems are better as they can support more memory. |
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|
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Any disk drive recognized by Linux (``IDE``/``SCSI``/``SATA``/etc.) |
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is 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 |
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used to store the images). It is highly recommended to use more than |
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one disk drive to improve speed. But Ganeti also works with one disk |
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per machine. |
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|
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Installing the base system |
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++++++++++++++++++++++++++ |
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|
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**Mandatory** on all nodes. |
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|
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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 |
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to partition leaving enough space for a big (**minimum** 20GiB) LVM |
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volume group which will then host your instance filesystems, if you |
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want to use all Ganeti features. The volume group name Ganeti 2.0 uses |
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(by default) is ``xenvg``. |
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|
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You can also use file-based storage only, without LVM, but this setup |
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is not detailed in this document. |
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|
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|
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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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|
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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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|
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Hostname issues |
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~~~~~~~~~~~~~~~ |
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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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|
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.. admonition:: Debian |
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|
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Debian Lenny and Etch configures the hostname differently than you |
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need it for Ganeti. For example, this is what Etch puts in |
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``/etc/hosts`` in certain situations:: |
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|
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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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|
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but for Ganeti you need to have:: |
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|
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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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|
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replacing ``192.168.1.1`` 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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|
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.. admonition:: Why a fully qualified host name |
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|
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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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|
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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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|
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|
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Installing The Hypervisor |
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+++++++++++++++++++++++++ |
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|
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**Mandatory** on all nodes. |
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|
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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, 3.0.4 |
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and 3.1. Supported KVM version are 72 and above. |
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|
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Please follow your distribution's recommended way to install and set |
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up Xen, or install Xen from the upstream source, if you wish, |
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following their manual. For KVM, make sure you have a KVM-enabled |
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kernel and the KVM tools. |
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|
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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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|
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.. admonition:: Xen on Debian |
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|
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Under Lenny or Etch you can install the relevant |
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``xen-linux-system`` package, which will pull in both the |
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hypervisor and the relevant kernel. Also, if you are installing a |
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32-bit Lenny/Etch, you should install the ``libc6-xen`` package |
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(run ``apt-get install libc6-xen``). |
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|
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Xen settings |
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~~~~~~~~~~~~ |
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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 |
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in the file ``/etc/xen/xend-config.sxp`` by setting |
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the value ``dom0-min-mem`` to 0, |
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like this:: |
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|
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(dom0-min-mem 0) |
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|
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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 |
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CPU only, for example by booting with the kernel parameter ``nosmp``. |
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|
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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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|
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.. admonition:: Debian |
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|
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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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|
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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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|
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and the ``xenkopt`` needs to include the ``nosmp`` option like |
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this:: |
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|
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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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|
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Any existing parameters can be left in place: it's ok to have |
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``xenkopt=console=tty0 nosmp``, for example. After modifying the |
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files, you need to run:: |
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|
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/sbin/update-grub |
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|
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If you want to run HVM instances too with Ganeti and want VNC access |
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to the console of your instances, set the following two entries in |
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``/etc/xen/xend-config.sxp``:: |
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|
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(vnc-listen '0.0.0.0') (vncpasswd '') |
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|
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You need to restart the Xen daemon for these settings to take effect:: |
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|
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/etc/init.d/xend restart |
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|
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Selecting the instance kernel |
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
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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 |
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creating a symlink from your actual kernel to |
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``/boot/vmlinuz-2.6-xenU``, and one from your initrd |
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to ``/boot/initrd-2.6-xenU``. Note that if you don't |
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use an initrd for the domU kernel, you don't need |
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to create the initrd symlink. |
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|
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.. admonition:: Debian |
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|
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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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|
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cd /boot |
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ln -s vmlinuz-2.6.26-1-xen-amd64 vmlinuz-2.6-xenU |
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ln -s initrd.img-2.6.26-1-xen-amd64 initrd-2.6-xenU |
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|
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Installing DRBD |
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+++++++++++++++ |
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|
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Recommended on all nodes: DRBD_ is required if you want to use the |
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high availability (HA) features of Ganeti, but optional if you don't |
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require HA or only run Ganeti on single-node clusters. You can upgrade |
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a non-HA cluster to an HA one later, but you might need to export and |
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re-import all your instances to take advantage of the new features. |
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|
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.. _DRBD: http://www.drbd.org/ |
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|
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Supported DRBD versions: 8.0.x. It's recommended to have at least |
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version 8.0.12. |
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|
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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 |
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fiddling with it. Hopefully at least the Xen-ified kernel source to |
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start from will be provided. |
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|
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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 |
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DRBD utils installed and the module in your kernel you're fine. Please |
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check that your system is configured to load the module at every boot, |
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and that it passes the following option to the module |
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``minor_count=255``. This will allow you to use up to 128 instances |
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per node (for most clusters 128 should be enough, though). |
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|
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.. admonition:: Debian |
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|
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On Debian, you can just install (build) the DRBD 8.0.x module with |
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the following commands (make sure you are running the Xen kernel):: |
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|
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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 >> /etc/modules |
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depmod -a |
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modprobe drbd minor_count=128 |
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|
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It is also recommended that you comment out the default resources |
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in the ``/etc/drbd.conf`` file, so that the init script doesn't try |
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to 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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|
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skip resource r0 { |
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... |
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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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|
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Other required software |
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+++++++++++++++++++++++ |
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|
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Besides Xen and DRBD, you will need to install the following (on all |
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nodes): |
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|
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- LVM version 2, `<http://sourceware.org/lvm2/>`_ |
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|
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- OpenSSL, `<http://www.openssl.org/>`_ |
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|
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- OpenSSH, `<http://www.openssh.com/portable.html>`_ |
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|
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- bridge utilities, `<http://bridge.sourceforge.net/>`_ |
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|
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- iproute2, `<http://developer.osdl.org/dev/iproute2>`_ |
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|
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- arping (part of iputils package), |
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`<ftp://ftp.inr.ac.ru/ip-routing/iputils-current.tar.gz>`_ |
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|
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- Python version 2.4 or 2.5, `<http://www.python.org>`_ |
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|
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- Python OpenSSL bindings, `<http://pyopenssl.sourceforge.net/>`_ |
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|
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- simplejson Python module, `<http://www.undefined.org/python/#simplejson>`_ |
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|
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- pyparsing Python module, `<http://pyparsing.wikispaces.com/>`_ |
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|
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- pyinotify Python module, `<http://trac.dbzteam.org/pyinotify>`_ |
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|
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These programs are supplied as part of most Linux distributions, so |
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usually they can be installed via apt or similar methods. Also many of |
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them will already be installed on a standard machine. |
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|
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|
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.. admonition:: Debian |
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|
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You can use this command line to install all needed packages:: |
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|
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# apt-get install lvm2 ssh bridge-utils iproute iputils-arping \ |
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python python-pyopenssl openssl python-pyparsing \ |
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python-simplejson python-pyinotify |
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|
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Setting up the environment for Ganeti |
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------------------------------------- |
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|
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Configuring the network |
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+++++++++++++++++++++++ |
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|
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**Mandatory** on all nodes. |
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|
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You can run Ganeti either in "bridge mode" or in "routed mode". In |
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bridge 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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|
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Beware that the default name Ganeti uses is ``xen-br0`` (which was |
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used in Xen 2.0) while Xen 3.0 uses ``xenbr0`` by default. The default |
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bridge your Ganeti cluster will use for new instances can be specified |
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at cluster initialization time. |
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|
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If you want to run in "routing mode" you need to specify that at cluster |
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init time (using the --nicparam option), and then no bridge will be |
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needed. In this mode instance traffic will be routed by dom0, instead of |
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bridged. |
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|
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In order to use "routing 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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|
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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 insulation 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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|
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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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|
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.. admonition:: Bridging under Debian |
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|
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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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|
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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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|
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The following commands need to be executed on the local console: |
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|
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ifdown eth0 |
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ifup xen-br0 |
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|
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To check if the bridge is setup, use the ``ip`` and ``brctl show`` |
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commands:: |
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|
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# ip a show xen-br0 |
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9: xen-br0: <BROADCAST,MULTICAST,UP,10000> mtu 1500 qdisc noqueue |
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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 |
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inet6 fe80::220:fcff:fe1e:d55d/64 scope link |
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valid_lft forever preferred_lft forever |
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|
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# 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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|
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Configuring LVM |
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+++++++++++++++ |
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|
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**Mandatory** on all nodes. |
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|
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The volume group is required to be at least 20GiB. |
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|
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If you haven't configured your LVM volume group at install time you |
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need to do it before trying to initialize the Ganeti cluster. This is |
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done by formatting the devices/partitions you want to use for it and |
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then adding them to the relevant volume group:: |
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|
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pvcreate /dev/sda3 |
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vgcreate xenvg /dev/sda3 |
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|
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or:: |
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|
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pvcreate /dev/sdb1 |
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pvcreate /dev/sdc1 |
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vgcreate xenvg /dev/sdb1 /dev/sdc1 |
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|
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If you want to add a device later you can do so with the *vgextend* |
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command:: |
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|
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pvcreate /dev/sdd1 |
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vgextend xenvg /dev/sdd1 |
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|
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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 |
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``/dev/drbd[0-9]+`` regular expression to the |
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``filter`` variable, like this:: |
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|
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filter = ["r|/dev/cdrom|", "r|/dev/drbd[0-9]+|" ] |
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|
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Installing Ganeti |
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+++++++++++++++++ |
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|
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**Mandatory** on all nodes. |
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|
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It's now time to install the Ganeti software itself. Download the |
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source from the project page at `<http://code.google.com/p/ganeti/>`_, |
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and install it (replace 2.0.0 with the latest version):: |
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|
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tar xvzf ganeti-2.0.0.tar.gz |
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cd ganeti-2.0.0 |
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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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|
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You also need to copy the file |
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``doc/examples/ganeti.initd`` from the source archive |
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to ``/etc/init.d/ganeti`` and register it with your |
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distribution's startup scripts, for example in Debian:: |
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|
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update-rc.d ganeti defaults 20 80 |
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|
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In order to automatically restart failed instances, you need to setup |
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a cron job run the *ganeti-watcher* command. A sample cron file is |
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provided in the source at ``doc/examples/ganeti.cron`` and you can |
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copy that (eventually altering the path) to ``/etc/cron.d/ganeti``. |
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|
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Installing the Operating System support packages |
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++++++++++++++++++++++++++++++++++++++++++++++++ |
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|
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**Mandatory** on all nodes. |
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|
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To be able to install instances you need to have an Operating System |
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installation script. An example OS that works under Debian and can |
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install Debian and Ubuntu instace OSes is provided on the project web |
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site. Download it from the project page and follow the instructions |
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in the ``README`` file. Here is the installation procedure (replace |
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0.7 with the latest version that is compatible with your ganeti |
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version):: |
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|
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cd /usr/local/src/ |
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wget http://ganeti.googlecode.com/files/ganeti-instance-debootstrap-0.7.tar.gz |
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tar xzf ganeti-instance-debootstrap-0.7.tar.gz |
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cd ganeti-instance-debootstrap-0.7 |
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./configure |
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make |
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make install |
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|
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In order to use this OS definition, you need to have internet access |
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from your nodes and have the *debootstrap*, *dump* and *restore* |
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commands installed on all nodes. Also, if the OS is configured to |
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partition the instance's disk in |
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``/etc/default/ganeti-instance-debootstrap``, you will need *kpartx* |
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installed. |
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|
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.. admonition:: Debian |
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|
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Use this command on all nodes to install the required packages:: |
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|
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apt-get install debootstrap dump kpartx |
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|
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Alternatively, you can create your own OS definitions. See the manpage |
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:manpage:`ganeti-os-interface`. |
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|
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Initializing the cluster |
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++++++++++++++++++++++++ |
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|
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**Mandatory** on one node per cluster. |
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|
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The last step is to initialize the cluster. After you've repeated the |
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above process on all of your nodes, choose one as the master, and |
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execute:: |
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|
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gnt-cluster init <CLUSTERNAME> |
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|
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The *CLUSTERNAME* is a hostname, which must be resolvable (e.g. it |
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must exist in DNS or in ``/etc/hosts``) by all the nodes in the |
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cluster. You must choose a name different from any of the nodes names |
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for a multi-node cluster. In general the best choice is to have a |
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unique name for a cluster, even if it consists of only one machine, as |
515 |
you will be able to expand it later without any problems. Please note |
516 |
that the hostname used for this must resolve to an IP address reserved |
517 |
**exclusively** for this purpose, and cannot be the name of the first |
518 |
(master) node. |
519 |
|
520 |
If you want to use a bridge which is not ``xen-br0``, or no bridge at |
521 |
all, use ``--nicparams``. |
522 |
|
523 |
If the bridge name you are using is not ``xen-br0``, use the *-b |
524 |
<BRIDGENAME>* option to specify the bridge name. In this case, you |
525 |
should also use the *--master-netdev <BRIDGENAME>* option with the |
526 |
same BRIDGENAME argument. |
527 |
|
528 |
You can use a different name than ``xenvg`` for the volume group (but |
529 |
note that the name must be identical on all nodes). In this case you |
530 |
need to specify it by passing the *-g <VGNAME>* option to |
531 |
``gnt-cluster init``. |
532 |
|
533 |
To set up the cluster as an HVM cluster, use the |
534 |
``--enabled-hypervisors=xen-hvm`` option to enable the HVM hypervisor |
535 |
(you can also add ``,xen-pvm`` to enable the PVM one too). You will |
536 |
also need to create the VNC cluster password file |
537 |
``/etc/ganeti/vnc-cluster-password`` which contains one line with the |
538 |
default VNC password for the cluster. |
539 |
|
540 |
To setup the cluster for KVM-only usage (KVM and Xen cannot be mixed), |
541 |
pass ``--enabled-hypervisors=kvm`` to the init command. |
542 |
|
543 |
You can also invoke the command with the ``--help`` option in order to |
544 |
see all the possibilities. |
545 |
|
546 |
Joining the nodes to the cluster |
547 |
++++++++++++++++++++++++++++++++ |
548 |
|
549 |
**Mandatory** for all the other nodes. |
550 |
|
551 |
After you have initialized your cluster you need to join the other |
552 |
nodes to it. You can do so by executing the following command on the |
553 |
master node:: |
554 |
|
555 |
gnt-node add <NODENAME> |
556 |
|
557 |
Separate replication network |
558 |
++++++++++++++++++++++++++++ |
559 |
|
560 |
**Optional** |
561 |
|
562 |
Ganeti uses DRBD to mirror the disk of the virtual instances between |
563 |
nodes. To use a dedicated network interface for this (in order to |
564 |
improve performance or to enhance security) you need to configure an |
565 |
additional interface for each node. Use the *-s* option with |
566 |
``gnt-cluster init`` and ``gnt-node add`` to specify the IP address of |
567 |
this secondary interface to use for each node. Note that if you |
568 |
specified this option at cluster setup time, you must afterwards use |
569 |
it for every node add operation. |
570 |
|
571 |
Testing the setup |
572 |
+++++++++++++++++ |
573 |
|
574 |
Execute the ``gnt-node list`` command to see all nodes in the |
575 |
cluster:: |
576 |
|
577 |
# gnt-node list |
578 |
Node DTotal DFree MTotal MNode MFree Pinst Sinst |
579 |
node1.example.com 197404 197404 2047 1896 125 0 0 |
580 |
|
581 |
Setting up and managing virtual instances |
582 |
----------------------------------------- |
583 |
|
584 |
Setting up virtual instances |
585 |
++++++++++++++++++++++++++++ |
586 |
|
587 |
This step shows how to setup a virtual instance with either |
588 |
non-mirrored disks (``plain``) or with network mirrored disks |
589 |
(``drbd``). All commands need to be executed on the Ganeti master |
590 |
node (the one on which ``gnt-cluster init`` was run). Verify that the |
591 |
OS scripts are present on all cluster nodes with ``gnt-os list``. |
592 |
|
593 |
|
594 |
To create a virtual instance, you need a hostname which is resolvable |
595 |
(DNS or ``/etc/hosts`` on all nodes). The following command will |
596 |
create a non-mirrored instance for you:: |
597 |
|
598 |
gnt-instance add -t plain -s 1G -n node1 -o debootstrap instance1.example.com |
599 |
* creating instance disks... |
600 |
adding instance instance1.example.com to cluster config |
601 |
- INFO: Waiting for instance instance1.example.com to sync disks. |
602 |
- INFO: Instance instance1.example.com's disks are in sync. |
603 |
creating os for instance instance1.example.com on node node1.example.com |
604 |
* running the instance OS create scripts... |
605 |
* starting instance... |
606 |
|
607 |
The above instance will have no network interface enabled. You can |
608 |
access it over the virtual console with ``gnt-instance console |
609 |
inst1``. There is no password for root. As this is a Debian instance, |
610 |
you can modify the ``/etc/network/interfaces`` file to setup the |
611 |
network interface (eth0 is the name of the interface provided to the |
612 |
instance). |
613 |
|
614 |
To create a network mirrored instance, change the argument to the *-t* |
615 |
option from ``plain`` to ``drbd`` and specify the node on which the |
616 |
mirror should reside with the second value of the *--node* option, |
617 |
like this (note that the command output includes timestamps which have |
618 |
been removed for clarity):: |
619 |
|
620 |
# gnt-instance add -t drbd -s 1G -n node1:node2 -o debootstrap instance2 |
621 |
* creating instance disks... |
622 |
adding instance instance2.example.com to cluster config |
623 |
- INFO: Waiting for instance instance2.example.com to sync disks. |
624 |
- INFO: - device disk/0: 35.50% done, 11 estimated seconds remaining |
625 |
- INFO: - device disk/0: 100.00% done, 0 estimated seconds remaining |
626 |
- INFO: Instance instance2.example.com's disks are in sync. |
627 |
creating os for instance instance2.example.com on node node1.example.com |
628 |
* running the instance OS create scripts... |
629 |
* starting instance... |
630 |
|
631 |
Managing virtual instances |
632 |
++++++++++++++++++++++++++ |
633 |
|
634 |
All commands need to be executed on the Ganeti master node. |
635 |
|
636 |
To access the console of an instance, run:: |
637 |
|
638 |
gnt-instance console INSTANCENAME |
639 |
|
640 |
To shutdown an instance, run:: |
641 |
|
642 |
gnt-instance shutdown INSTANCENAME |
643 |
|
644 |
To startup an instance, run:: |
645 |
|
646 |
gnt-instance startup INSTANCENAME |
647 |
|
648 |
To failover an instance to its secondary node (only possible with |
649 |
``drbd`` disk templates), run:: |
650 |
|
651 |
gnt-instance failover INSTANCENAME |
652 |
|
653 |
For more instance and cluster administration details, see the |
654 |
*Ganeti administrator's guide*. |
655 |
|
656 |
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