1 Ganeti installation tutorial
2 ============================
4 Documents Ganeti version |version|
13 Ganeti is a cluster virtualization management system based on Xen or
14 KVM. This document explains how to bootstrap a Ganeti node (Xen *dom0*,
15 the host Linux system for KVM), create a running cluster and install
16 virtual instances (Xen *domUs*, KVM guests). You need to repeat most of
17 the steps in this document for every node you want to install, but of
18 course we recommend creating some semi-automatic procedure if you plan
19 to deploy Ganeti on a medium/large scale.
21 A basic Ganeti terminology glossary is provided in the introductory
22 section of the :doc:`admin`. Please refer to that document if you are
23 uncertain about the terms we are using.
25 Ganeti has been developed for Linux and should be distribution-agnostic.
26 This documentation will use Debian Lenny as an example system but the
27 examples can be translated to any other distribution. You are expected
28 to be familiar with your distribution, its package management system,
29 and Xen or KVM before trying to use Ganeti.
31 This document is divided into two main sections:
33 - Installation of the base system and base components
35 - Configuration of the environment for Ganeti
37 Each of these is divided into sub-sections. While a full Ganeti system
38 will need all of the steps specified, some are not strictly required for
39 every environment. Which ones they are, and why, is specified in the
40 corresponding sections.
42 Installing the base system and base components
43 ----------------------------------------------
48 Any system supported by your Linux distribution is fine. 64-bit systems
49 are better as they can support more memory.
51 Any disk drive recognized by Linux (``IDE``/``SCSI``/``SATA``/etc.) is
52 supported in Ganeti. Note that no shared storage (e.g. ``SAN``) is
53 needed to get high-availability features (but of course, one can be used
54 to store the images). It is highly recommended to use more than one disk
55 drive to improve speed. But Ganeti also works with one disk per machine.
57 Installing the base system
58 ++++++++++++++++++++++++++
60 **Mandatory** on all nodes.
62 It is advised to start with a clean, minimal install of the operating
63 system. The only requirement you need to be aware of at this stage is to
64 partition leaving enough space for a big (**minimum** 20GiB) LVM volume
65 group which will then host your instance filesystems, if you want to use
66 all Ganeti features. The volume group name Ganeti uses (by default) is
69 You can also use file-based storage only, without LVM, but this setup is
70 not detailed in this document.
72 While you can use an existing system, please note that the Ganeti
73 installation is intrusive in terms of changes to the system
74 configuration, and it's best to use a newly-installed system without
77 Also, for best results, it's advised that the nodes have as much as
78 possible the same hardware and software configuration. This will make
79 administration much easier.
84 Note that Ganeti requires the hostnames of the systems (i.e. what the
85 ``hostname`` command outputs to be a fully-qualified name, not a short
86 name. In other words, you should use *node1.example.com* as a hostname
89 .. admonition:: Debian
91 Debian Lenny and Etch configures the hostname differently than you
92 need it for Ganeti. For example, this is what Etch puts in
93 ``/etc/hosts`` in certain situations::
96 127.0.1.1 node1.example.com node1
98 but for Ganeti you need to have::
101 192.168.1.1 node1.example.com node1
103 replacing ``192.168.1.1`` with your node's address. Also, the file
104 ``/etc/hostname`` which configures the hostname of the system
105 should contain ``node1.example.com`` and not just ``node1`` (you
106 need to run the command ``/etc/init.d/hostname.sh start`` after
109 .. admonition:: Why a fully qualified host name
111 Although most distributions use only the short name in the
112 /etc/hostname file, we still think Ganeti nodes should use the full
113 name. The reason for this is that calling 'hostname --fqdn' requires
114 the resolver library to work and is a 'guess' via heuristics at what
115 is your domain name. Since Ganeti can be used among other things to
116 host DNS servers, we don't want to depend on them as much as
117 possible, and we'd rather have the uname() syscall return the full
120 We haven't ever found any breakage in using a full hostname on a
121 Linux system, and anyway we recommend to have only a minimal
122 installation on Ganeti nodes, and to use instances (or other
123 dedicated machines) to run the rest of your network services. By
124 doing this you can change the /etc/hostname file to contain an FQDN
125 without the fear of breaking anything unrelated.
128 Installing The Hypervisor
129 +++++++++++++++++++++++++
131 **Mandatory** on all nodes.
133 While Ganeti is developed with the ability to modularly run on different
134 virtualization environments in mind the only two currently useable on a
135 live system are Xen and KVM. Supported Xen versions are: 3.0.3, 3.0.4
136 and 3.1. Supported KVM version are 72 and above.
138 Please follow your distribution's recommended way to install and set up
139 Xen, or install Xen from the upstream source, if you wish, following
140 their manual. For KVM, make sure you have a KVM-enabled kernel and the
143 After installing Xen, you need to reboot into your new system. On some
144 distributions this might involve configuring GRUB appropriately, whereas
145 others will configure it automatically when you install the respective
146 kernels. For KVM no reboot should be necessary.
148 .. admonition:: Xen on Debian
150 Under Lenny or Etch you can install the relevant ``xen-linux-system``
151 package, which will pull in both the hypervisor and the relevant
152 kernel. Also, if you are installing a 32-bit Lenny/Etch, you should
153 install the ``libc6-xen`` package (run ``apt-get install
159 It's recommended that dom0 is restricted to a low amount of memory
160 (512MiB or 1GiB is reasonable) and that memory ballooning is disabled in
161 the file ``/etc/xen/xend-config.sxp`` by setting the value
162 ``dom0-min-mem`` to 0, like this::
166 For optimum performance when running both CPU and I/O intensive
167 instances, it's also recommended that the dom0 is restricted to one CPU
168 only, for example by booting with the kernel parameter ``nosmp``.
170 It is recommended that you disable xen's automatic save of virtual
171 machines at system shutdown and subsequent restore of them at reboot.
172 To obtain this make sure the variable ``XENDOMAINS_SAVE`` in the file
173 ``/etc/default/xendomains`` is set to an empty value.
175 If you want to use live migration make sure you have, in the xen config
176 file, something that allows the nodes to migrate instances between each
179 (xend-relocation-server yes)
180 (xend-relocation-port 8002)
181 (xend-relocation-address '')
182 (xend-relocation-hosts-allow '^192\\.168\\.3\\.[0-9]+$')
185 The second line assumess that the hypervisor parameter
186 ``migration_port`` is set 8002, otherwise modify it to match. The last
187 line assumes that all your nodes have secondary IPs in the
188 192.168.3.0/24 network, adjust it accordingly to your setup.
190 .. admonition:: Debian
192 Besides the ballooning change which you need to set in
193 ``/etc/xen/xend-config.sxp``, you need to set the memory and nosmp
194 parameters in the file ``/boot/grub/menu.lst``. You need to modify
195 the variable ``xenhopt`` to add ``dom0_mem=1024M`` like this::
197 ## Xen hypervisor options to use with the default Xen boot option
198 # xenhopt=dom0_mem=1024M
200 and the ``xenkopt`` needs to include the ``nosmp`` option like this::
202 ## Xen Linux kernel options to use with the default Xen boot option
205 Any existing parameters can be left in place: it's ok to have
206 ``xenkopt=console=tty0 nosmp``, for example. After modifying the
207 files, you need to run::
211 If you want to run HVM instances too with Ganeti and want VNC access to
212 the console of your instances, set the following two entries in
213 ``/etc/xen/xend-config.sxp``::
215 (vnc-listen '0.0.0.0') (vncpasswd '')
217 You need to restart the Xen daemon for these settings to take effect::
219 /etc/init.d/xend restart
221 Selecting the instance kernel
222 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
224 After you have installed Xen, you need to tell Ganeti exactly what
225 kernel to use for the instances it will create. This is done by creating
226 a symlink from your actual kernel to ``/boot/vmlinuz-2.6-xenU``, and one
227 from your initrd to ``/boot/initrd-2.6-xenU`` [#defkernel]_. Note that
228 if you don't use an initrd for the domU kernel, you don't need to create
231 .. admonition:: Debian
233 After installation of the ``xen-linux-system`` package, you need to
234 run (replace the exact version number with the one you have)::
237 ln -s vmlinuz-2.6.26-1-xen-amd64 vmlinuz-2.6-xenU
238 ln -s initrd.img-2.6.26-1-xen-amd64 initrd-2.6-xenU
243 Recommended on all nodes: DRBD_ is required if you want to use the high
244 availability (HA) features of Ganeti, but optional if you don't require
245 them or only run Ganeti on single-node clusters. You can upgrade a
246 non-HA cluster to an HA one later, but you might need to export and
247 re-import all your instances to take advantage of the new features.
249 .. _DRBD: http://www.drbd.org/
251 Supported DRBD versions: 8.0+. It's recommended to have at least version
252 8.0.12. Note that for version 8.2 and newer it is needed to pass the
253 ``usermode_helper=/bin/true`` parameter to the module, either by
254 configuring ``/etc/modules`` or when inserting it manually.
256 Now the bad news: unless your distribution already provides it
257 installing DRBD might involve recompiling your kernel or anyway fiddling
258 with it. Hopefully at least the Xen-ified kernel source to start from
259 will be provided (if you intend to use Xen).
261 The good news is that you don't need to configure DRBD at all. Ganeti
262 will do it for you for every instance you set up. If you have the DRBD
263 utils installed and the module in your kernel you're fine. Please check
264 that your system is configured to load the module at every boot, and
265 that it passes the following option to the module:
266 ``minor_count=NUMBER``. We recommend that you use 128 as the value of
267 the minor_count - this will allow you to use up to 64 instances in total
268 per node (both primary and secondary, when using only one disk per
269 instance). You can increase the number up to 255 if you need more
273 .. admonition:: Debian
275 On Debian, you can just install (build) the DRBD module with the
276 following commands, making sure you are running the target (Xen or
279 apt-get install drbd8-source drbd8-utils
282 echo drbd minor_count=128 usermode_helper=/bin/true >> /etc/modules
284 modprobe drbd minor_count=128 usermode_helper=/bin/true
286 It is also recommended that you comment out the default resources in
287 the ``/etc/drbd.conf`` file, so that the init script doesn't try to
288 configure any drbd devices. You can do this by prefixing all
289 *resource* lines in the file with the keyword *skip*, like this::
299 Other required software
300 +++++++++++++++++++++++
302 See :doc:`install-quick`.
304 Setting up the environment for Ganeti
305 -------------------------------------
307 Configuring the network
308 +++++++++++++++++++++++
310 **Mandatory** on all nodes.
312 You can run Ganeti either in "bridge mode" or in "routed mode". In
313 bridge mode, the default, the instances network interfaces will be
314 attached to a software bridge running in dom0. Xen by default creates
315 such a bridge at startup, but your distribution might have a different
316 way to do things, and you'll definitely need to manually set it up under
319 Beware that the default name Ganeti uses is ``xen-br0`` (which was used
320 in Xen 2.0) while Xen 3.0 uses ``xenbr0`` by default. See the
321 `Initializing the cluster`_ section to learn how to choose a different
322 bridge, or not to use one at all and use "routed mode".
324 In order to use "routed mode" under Xen, you'll need to change the
325 relevant parameters in the Xen config file. Under KVM instead, no config
326 change is necessary, but you still need to set up your network
327 interfaces correctly.
329 By default, under KVM, the "link" parameter you specify per-nic will
330 represent, if non-empty, a different routing table name or number to use
331 for your instances. This allows insulation between different instance
332 groups, and different routing policies between node traffic and instance
335 You will need to configure your routing table basic routes and rules
336 outside of ganeti. The vif scripts will only add /32 routes to your
337 instances, through their interface, in the table you specified (under
338 KVM, and in the main table under Xen).
340 .. admonition:: Bridging under Debian
342 The recommended way to configure the Xen bridge is to edit your
343 ``/etc/network/interfaces`` file and substitute your normal
344 Ethernet stanza with the following snippet::
347 iface xen-br0 inet static
348 address YOUR_IP_ADDRESS
351 broadcast YOUR_BROADCAST_ADDRESS
357 The following commands need to be executed on the local console:
362 To check if the bridge is setup, use the ``ip`` and ``brctl show``
366 9: xen-br0: <BROADCAST,MULTICAST,UP,10000> mtu 1500 qdisc noqueue
367 link/ether 00:20:fc:1e:d5:5d brd ff:ff:ff:ff:ff:ff
368 inet 10.1.1.200/24 brd 10.1.1.255 scope global xen-br0
369 inet6 fe80::220:fcff:fe1e:d55d/64 scope link
370 valid_lft forever preferred_lft forever
373 bridge name bridge id STP enabled interfaces
374 xen-br0 8000.0020fc1ed55d no eth0
376 .. _configure-lvm-label:
381 **Mandatory** on all nodes.
383 The volume group is required to be at least 20GiB.
385 If you haven't configured your LVM volume group at install time you need
386 to do it before trying to initialize the Ganeti cluster. This is done by
387 formatting the devices/partitions you want to use for it and then adding
388 them to the relevant volume group::
391 vgcreate xenvg /dev/sda3
397 vgcreate xenvg /dev/sdb1 /dev/sdc1
399 If you want to add a device later you can do so with the *vgextend*
403 vgextend xenvg /dev/sdd1
405 Optional: it is recommended to configure LVM not to scan the DRBD
406 devices for physical volumes. This can be accomplished by editing
407 ``/etc/lvm/lvm.conf`` and adding the ``/dev/drbd[0-9]+`` regular
408 expression to the ``filter`` variable, like this::
410 filter = ["r|/dev/cdrom|", "r|/dev/drbd[0-9]+|" ]
412 Note that with Ganeti a helper script is provided - ``lvmstrap`` which
413 will erase and configure as LVM any not in-use disk on your system. This
414 is dangerous and it's recommended to read its ``--help`` output if you
420 **Mandatory** on all nodes.
422 It's now time to install the Ganeti software itself. Download the
423 source from the project page at `<http://code.google.com/p/ganeti/>`_,
424 and install it (replace 2.0.0 with the latest version)::
426 tar xvzf ganeti-2.0.0.tar.gz
428 ./configure --localstatedir=/var --sysconfdir=/etc
431 mkdir /srv/ganeti/ /srv/ganeti/os /srv/ganeti/export
433 You also need to copy the file ``doc/examples/ganeti.initd`` from the
434 source archive to ``/etc/init.d/ganeti`` and register it with your
435 distribution's startup scripts, for example in Debian::
437 update-rc.d ganeti defaults 20 80
439 In order to automatically restart failed instances, you need to setup a
440 cron job run the *ganeti-watcher* command. A sample cron file is
441 provided in the source at ``doc/examples/ganeti.cron`` and you can copy
442 that (eventually altering the path) to ``/etc/cron.d/ganeti``.
447 The above ``make install`` invocation, or installing via your
448 distribution mechanisms, will install on the system:
450 - a set of python libraries under the *ganeti* namespace (depending on
451 the python version this can be located in either
452 ``lib/python-$ver/site-packages`` or various other locations)
453 - a set of programs under ``/usr/local/sbin`` or ``/usr/sbin``
454 - man pages for the above programs
455 - a set of tools under the ``lib/ganeti/tools`` directory
456 - an example iallocator script (see the admin guide for details) under
457 ``lib/ganeti/iallocators``
458 - a cron job that is needed for cluster maintenance
459 - an init script for automatic startup of Ganeti daemons
460 - provided but not installed automatically by ``make install`` is a bash
461 completion script that hopefully will ease working with the many
464 Installing the Operating System support packages
465 ++++++++++++++++++++++++++++++++++++++++++++++++
467 **Mandatory** on all nodes.
469 To be able to install instances you need to have an Operating System
470 installation script. An example OS that works under Debian and can
471 install Debian and Ubuntu instace OSes is provided on the project web
472 site. Download it from the project page and follow the instructions in
473 the ``README`` file. Here is the installation procedure (replace 0.9
474 with the latest version that is compatible with your ganeti version)::
477 wget http://ganeti.googlecode.com/files/ganeti-instance-debootstrap-0.9.tar.gz
478 tar xzf ganeti-instance-debootstrap-0.9.tar.gz
479 cd ganeti-instance-debootstrap-0.9
484 In order to use this OS definition, you need to have internet access
485 from your nodes and have the *debootstrap*, *dump* and *restore*
486 commands installed on all nodes. Also, if the OS is configured to
487 partition the instance's disk in
488 ``/etc/default/ganeti-instance-debootstrap``, you will need *kpartx*
491 .. admonition:: Debian
493 Use this command on all nodes to install the required packages::
495 apt-get install debootstrap dump kpartx
499 In order for debootstrap instances to be able to shutdown cleanly
500 they must install have basic acpi support inside the instance. Which
501 packages are needed depend on the exact flavor of debian or ubuntu
502 which you're installing, but the example defaults file has a
503 commented out configuration line that works for debian lenny and
506 EXTRA_PKGS="acpi-support-base,console-tools,udev"
508 kbd can be used instead of console-tools, and more packages can be
509 added, of course, if needed.
511 Alternatively, you can create your own OS definitions. See the manpage
512 :manpage:`ganeti-os-interface`.
514 Initializing the cluster
515 ++++++++++++++++++++++++
517 **Mandatory** once per cluster, on the first node.
519 The last step is to initialize the cluster. After you have repeated the
520 above process on all of your nodes, choose one as the master, and
523 gnt-cluster init <CLUSTERNAME>
525 The *CLUSTERNAME* is a hostname, which must be resolvable (e.g. it must
526 exist in DNS or in ``/etc/hosts``) by all the nodes in the cluster. You
527 must choose a name different from any of the nodes names for a
528 multi-node cluster. In general the best choice is to have a unique name
529 for a cluster, even if it consists of only one machine, as you will be
530 able to expand it later without any problems. Please note that the
531 hostname used for this must resolve to an IP address reserved
532 **exclusively** for this purpose, and cannot be the name of the first
535 If you want to use a bridge which is not ``xen-br0``, or no bridge at
536 all, change it with the ``--nic-parameters`` option. For example to
537 bridge on br0 you can say::
539 --nic-parameters link=br0
541 Or to not bridge at all, and use a separate routing table::
543 --nic-parameters mode=routed,link=100
545 If you don't have a xen-br0 interface you also have to specify a
546 different network interface which will get the cluster ip, on the master
547 node, by using the ``--master-netdev <device>`` option.
549 You can use a different name than ``xenvg`` for the volume group (but
550 note that the name must be identical on all nodes). In this case you
551 need to specify it by passing the *-g <VGNAME>* option to ``gnt-cluster
554 To set up the cluster as an Xen HVM cluster, use the
555 ``--enabled-hypervisors=xen-hvm`` option to enable the HVM hypervisor
556 (you can also add ``,xen-pvm`` to enable the PVM one too). You will also
557 need to create the VNC cluster password file
558 ``/etc/ganeti/vnc-cluster-password`` which contains one line with the
559 default VNC password for the cluster.
561 To setup the cluster for KVM-only usage (KVM and Xen cannot be mixed),
562 pass ``--enabled-hypervisors=kvm`` to the init command.
564 You can also invoke the command with the ``--help`` option in order to
565 see all the possibilities.
567 Hypervisor/Network/Cluster parameters
568 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
570 Please note that the default hypervisor/network/cluster parameters may
571 not be the correct one for your environment. Carefully check them, and
572 change them at cluster init time, or later with ``gnt-cluster modify``.
574 Your instance types, networking environment, hypervisor type and version
575 may all affect what kind of parameters should be used on your cluster.
577 For example kvm instances are by default configured to use a host
578 kernel, and to be reached via serial console, which works nice for linux
579 paravirtualized instances. If you want fully virtualized instances you
580 may want to handle their kernel inside the instance, and to use VNC.
582 Joining the nodes to the cluster
583 ++++++++++++++++++++++++++++++++
585 **Mandatory** for all the other nodes.
587 After you have initialized your cluster you need to join the other nodes
588 to it. You can do so by executing the following command on the master
591 gnt-node add <NODENAME>
593 Separate replication network
594 ++++++++++++++++++++++++++++
598 Ganeti uses DRBD to mirror the disk of the virtual instances between
599 nodes. To use a dedicated network interface for this (in order to
600 improve performance or to enhance security) you need to configure an
601 additional interface for each node. Use the *-s* option with
602 ``gnt-cluster init`` and ``gnt-node add`` to specify the IP address of
603 this secondary interface to use for each node. Note that if you
604 specified this option at cluster setup time, you must afterwards use it
605 for every node add operation.
610 Execute the ``gnt-node list`` command to see all nodes in the cluster::
613 Node DTotal DFree MTotal MNode MFree Pinst Sinst
614 node1.example.com 197404 197404 2047 1896 125 0 0
616 The above shows a couple of things:
618 - The various Ganeti daemons can talk to each other
619 - Ganeti can examine the storage of the node (DTotal/DFree)
620 - Ganeti can talk to the selected hypervisor (MTotal/MNode/MFree)
625 With Ganeti a tool called :command:`burnin` is provided that can test
626 most of the Ganeti functionality. The tool is installed under the
627 ``lib/ganeti/tools`` directory (either under ``/usr`` or ``/usr/local``
628 based on the installation method). See more details under
634 You can now proceed either to the :doc:`admin`, or read the manpages of
635 the various commands (:manpage:`ganeti(7)`, :manpage:`gnt-cluster(8)`,
636 :manpage:`gnt-node(8)`, :manpage:`gnt-instance(8)`,
637 :manpage:`gnt-job(8)`).
639 .. rubric:: Footnotes
641 .. [#defkernel] The kernel and initrd paths can be changed at either
642 cluster level (which changes the default for all instances) or at
645 .. vim: set textwidth=72 :