1 Ganeti administrator's guide
2 ============================
4 Documents Ganeti version |version|
13 Ganeti is a virtualization cluster management software. You are expected
14 to be a system administrator familiar with your Linux distribution and
15 the Xen or KVM virtualization environments before using it.
17 The various components of Ganeti all have man pages and interactive
18 help. This manual though will help you getting familiar with the system
19 by explaining the most common operations, grouped by related use.
21 After a terminology glossary and a section on the prerequisites needed
22 to use this manual, the rest of this document is divided in sections
23 for the different targets that a command affects: instance, nodes, etc.
25 .. _terminology-label:
30 This section provides a small introduction to Ganeti terminology, which
31 might be useful when reading the rest of the document.
36 A set of machines (nodes) that cooperate to offer a coherent, highly
37 available virtualization service under a single administration domain.
42 A physical machine which is member of a cluster. Nodes are the basic
43 cluster infrastructure, and they don't need to be fault tolerant in
44 order to achieve high availability for instances.
46 Node can be added and removed (if they host no instances) at will from
47 the cluster. In a HA cluster and only with HA instances, the loss of any
48 single node will not cause disk data loss for any instance; of course,
49 a node crash will cause the crash of the its primary instances.
51 A node belonging to a cluster can be in one of the following roles at a
54 - *master* node, which is the node from which the cluster is controlled
55 - *master candidate* node, only nodes in this role have the full cluster
56 configuration and knowledge, and only master candidates can become the
58 - *regular* node, which is the state in which most nodes will be on
59 bigger clusters (>20 nodes)
60 - *drained* node, nodes in this state are functioning normally but the
61 cannot receive new instances; the intention is that nodes in this role
62 have some issue and they are being evacuated for hardware repairs
63 - *offline* node, in which there is a record in the cluster
64 configuration about the node, but the daemons on the master node will
65 not talk to this node; any instances declared as having an offline
66 node as either primary or secondary will be flagged as an error in the
67 cluster verify operation
69 Depending on the role, each node will run a set of daemons:
71 - the :command:`ganeti-noded` daemon, which control the manipulation of
72 this node's hardware resources; it runs on all nodes which are in a
74 - the :command:`ganeti-confd` daemon (Ganeti 2.1+) which runs on all
75 nodes, but is only functional on master candidate nodes
76 - the :command:`ganeti-rapi` daemon which runs on the master node and
77 offers an HTTP-based API for the cluster
78 - the :command:`ganeti-masterd` daemon which runs on the master node and
79 allows control of the cluster
81 Beside the node role, there are other node flags that influence its
84 - the *master_capable* flag denotes whether the node can ever become a
85 master candidate; setting this to 'no' means that auto-promotion will
86 never make this node a master candidate; this flag can be useful for a
87 remote node that only runs local instances, and having it become a
88 master is impractical due to networking or other constraints
89 - the *vm_capable* flag denotes whether the node can host instances or
90 not; for example, one might use a non-vm_capable node just as a master
91 candidate, for configuration backups; setting this flag to no
92 disallows placement of instances of this node, deactivates hypervisor
93 and related checks on it (e.g. bridge checks, LVM check, etc.), and
94 removes it from cluster capacity computations
100 A virtual machine which runs on a cluster. It can be a fault tolerant,
101 highly available entity.
103 An instance has various parameters, which are classified in three
104 categories: hypervisor related-parameters (called ``hvparams``), general
105 parameters (called ``beparams``) and per network-card parameters (called
106 ``nicparams``). All these parameters can be modified either at instance
107 level or via defaults at cluster level.
112 The are multiple options for the storage provided to an instance; while
113 the instance sees the same virtual drive in all cases, the node-level
114 configuration varies between them.
116 There are four disk templates you can choose from:
119 The instance has no disks. Only used for special purpose operating
120 systems or for testing.
123 The instance will use plain files as backend for its disks. No
124 redundancy is provided, and this is somewhat more difficult to
125 configure for high performance.
128 The instance will use LVM devices as backend for its disks. No
129 redundancy is provided.
132 .. note:: This is only valid for multi-node clusters using DRBD 8.0+
134 A mirror is set between the local node and a remote one, which must be
135 specified with the second value of the --node option. Use this option
136 to obtain a highly available instance that can be failed over to a
137 remote node should the primary one fail.
142 A framework for using external (user-provided) scripts to compute the
143 placement of instances on the cluster nodes. This eliminates the need to
144 manually specify nodes in instance add, instance moves, node evacuate,
147 In order for Ganeti to be able to use these scripts, they must be place
148 in the iallocator directory (usually ``lib/ganeti/iallocators`` under
149 the installation prefix, e.g. ``/usr/local``).
151 “Primary” and “secondary” concepts
152 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
154 An instance has a primary and depending on the disk configuration, might
155 also have a secondary node. The instance always runs on the primary node
156 and only uses its secondary node for disk replication.
158 Similarly, the term of primary and secondary instances when talking
159 about a node refers to the set of instances having the given node as
160 primary, respectively secondary.
165 Tags are short strings that can be attached to either to cluster itself,
166 or to nodes or instances. They are useful as a very simplistic
167 information store for helping with cluster administration, for example
168 by attaching owner information to each instance after it's created::
170 gnt-instance add … instance1
171 gnt-instance add-tags instance1 owner:user2
173 And then by listing each instance and its tags, this information could
174 be used for contacting the users of each instance.
179 While not directly visible by an end-user, it's useful to know that a
180 basic cluster operation (e.g. starting an instance) is represented
181 internall by Ganeti as an *OpCode* (abbreviation from operation
182 code). These OpCodes are executed as part of a *Job*. The OpCodes in a
183 single Job are processed serially by Ganeti, but different Jobs will be
184 processed (depending on resource availability) in parallel. They will
185 not be executed in the submission order, but depending on resource
186 availability, locks and (starting with Ganeti 2.3) priority. An earlier
187 job may have to wait for a lock while a newer job doesn't need any locks
188 and can be executed right away. Operations requiring a certain order
189 need to be submitted as a single job, or the client must submit one job
190 at a time and wait for it to finish before continuing.
192 For example, shutting down the entire cluster can be done by running the
193 command ``gnt-instance shutdown --all``, which will submit for each
194 instance a separate job containing the “shutdown instance” OpCode.
200 You need to have your Ganeti cluster installed and configured before you
201 try any of the commands in this document. Please follow the
202 :doc:`install` for instructions on how to do that.
210 The add operation might seem complex due to the many parameters it
211 accepts, but once you have understood the (few) required parameters and
212 the customisation capabilities you will see it is an easy operation.
214 The add operation requires at minimum five parameters:
216 - the OS for the instance
218 - the disk count and size
219 - the node specification or alternatively the iallocator to use
220 - and finally the instance name
222 The OS for the instance must be visible in the output of the command
223 ``gnt-os list`` and specifies which guest OS to install on the instance.
225 The disk template specifies what kind of storage to use as backend for
226 the (virtual) disks presented to the instance; note that for instances
227 with multiple virtual disks, they all must be of the same type.
229 The node(s) on which the instance will run can be given either manually,
230 via the ``-n`` option, or computed automatically by Ganeti, if you have
231 installed any iallocator script.
233 With the above parameters in mind, the command is::
236 -n TARGET_NODE:SECONDARY_NODE \
238 -t DISK_TEMPLATE -s DISK_SIZE \
241 The instance name must be resolvable (e.g. exist in DNS) and usually
242 points to an address in the same subnet as the cluster itself.
244 The above command has the minimum required options; other options you
245 can give include, among others:
247 - The memory size (``-B memory``)
249 - The number of virtual CPUs (``-B vcpus``)
251 - Arguments for the NICs of the instance; by default, a single-NIC
252 instance is created. The IP and/or bridge of the NIC can be changed
253 via ``--nic 0:ip=IP,bridge=BRIDGE``
255 See the manpage for gnt-instance for the detailed option list.
257 For example if you want to create an highly available instance, with a
258 single disk of 50GB and the default memory size, having primary node
259 ``node1`` and secondary node ``node3``, use the following command::
261 gnt-instance add -n node1:node3 -o debootstrap -t drbd \
264 There is a also a command for batch instance creation from a
265 specification file, see the ``batch-create`` operation in the
266 gnt-instance manual page.
268 Regular instance operations
269 +++++++++++++++++++++++++++
274 Removing an instance is even easier than creating one. This operation is
275 irreversible and destroys all the contents of your instance. Use with
278 gnt-instance remove INSTANCE_NAME
283 Instances are automatically started at instance creation time. To
284 manually start one which is currently stopped you can run::
286 gnt-instance startup INSTANCE_NAME
288 While the command to stop one is::
290 gnt-instance shutdown INSTANCE_NAME
292 .. warning:: Do not use the Xen or KVM commands directly to stop
293 instances. If you run for example ``xm shutdown`` or ``xm destroy``
294 on an instance Ganeti will automatically restart it (via
295 the :command:`ganeti-watcher` command which is launched via cron).
300 There are two ways to get information about instances: listing
301 instances, which does a tabular output containing a given set of fields
302 about each instance, and querying detailed information about a set of
305 The command to see all the instances configured and their status is::
309 The command can return a custom set of information when using the ``-o``
310 option (as always, check the manpage for a detailed specification). Each
311 instance will be represented on a line, thus making it easy to parse
312 this output via the usual shell utilities (grep, sed, etc.).
314 To get more detailed information about an instance, you can run::
316 gnt-instance info INSTANCE
318 which will give a multi-line block of information about the instance,
319 it's hardware resources (especially its disks and their redundancy
320 status), etc. This is harder to parse and is more expensive than the
321 list operation, but returns much more detailed information.
327 You can create a snapshot of an instance disk and its Ganeti
328 configuration, which then you can backup, or import into another
329 cluster. The way to export an instance is::
331 gnt-backup export -n TARGET_NODE INSTANCE_NAME
334 The target node can be any node in the cluster with enough space under
335 ``/srv/ganeti`` to hold the instance image. Use the ``--noshutdown``
336 option to snapshot an instance without rebooting it. Note that Ganeti
337 only keeps one snapshot for an instance - any previous snapshot of the
338 same instance existing cluster-wide under ``/srv/ganeti`` will be
339 removed by this operation: if you want to keep them, you need to move
340 them out of the Ganeti exports directory.
342 Importing an instance is similar to creating a new one, but additionally
343 one must specify the location of the snapshot. The command is::
345 gnt-backup import -n TARGET_NODE \
346 --src-node=NODE --src-dir=DIR INSTANCE_NAME
348 By default, parameters will be read from the export information, but you
349 can of course pass them in via the command line - most of the options
350 available for the command :command:`gnt-instance add` are supported here
353 Import of foreign instances
354 +++++++++++++++++++++++++++
356 There is a possibility to import a foreign instance whose disk data is
357 already stored as LVM volumes without going through copying it: the disk
360 For this, ensure that the original, non-managed instance is stopped,
361 then create a Ganeti instance in the usual way, except that instead of
362 passing the disk information you specify the current volumes::
364 gnt-instance add -t plain -n HOME_NODE ... \
365 --disk 0:adopt=lv_name[,vg=vg_name] INSTANCE_NAME
367 This will take over the given logical volumes, rename them to the Ganeti
368 standard (UUID-based), and without installing the OS on them start
369 directly the instance. If you configure the hypervisor similar to the
370 non-managed configuration that the instance had, the transition should
371 be seamless for the instance. For more than one disk, just pass another
372 disk parameter (e.g. ``--disk 1:adopt=...``).
374 Instance kernel selection
375 +++++++++++++++++++++++++
377 The kernel that instances uses to bootup can come either from the node,
378 or from instances themselves, depending on the setup.
383 With Xen PVM, there are three options.
385 First, you can use a kernel from the node, by setting the hypervisor
388 - ``kernel_path`` to a valid file on the node (and appropriately
390 - ``kernel_args`` optionally set to a valid Linux setting (e.g. ``ro``)
391 - ``root_path`` to a valid setting (e.g. ``/dev/xvda1``)
392 - ``bootloader_path`` and ``bootloader_args`` to empty
394 Alternatively, you can delegate the kernel management to instances, and
395 use either ``pvgrub`` or the deprecated ``pygrub``. For this, you must
396 install the kernels and initrds in the instance and create a valid GRUB
397 v1 configuration file.
399 For ``pvgrub`` (new in version 2.4.2), you need to set:
401 - ``kernel_path`` to point to the ``pvgrub`` loader present on the node
402 (e.g. ``/usr/lib/xen/boot/pv-grub-x86_32.gz``)
403 - ``kernel_args`` to the path to the GRUB config file, relative to the
404 instance (e.g. ``(hd0,0)/grub/menu.lst``)
405 - ``root_path`` **must** be empty
406 - ``bootloader_path`` and ``bootloader_args`` to empty
408 While ``pygrub`` is deprecated, here is how you can configure it:
410 - ``bootloader_path`` to the pygrub binary (e.g. ``/usr/bin/pygrub``)
411 - the other settings are not important
413 More information can be found in the Xen wiki pages for `pvgrub
414 <http://wiki.xensource.com/xenwiki/PvGrub>`_ and `pygrub
415 <http://wiki.xensource.com/xenwiki/PyGrub>`_.
420 For KVM also the kernel can be loaded either way.
422 For loading the kernels from the node, you need to set:
424 - ``kernel_path`` to a valid value
425 - ``initrd_path`` optionally set if you use an initrd
426 - ``kernel_args`` optionally set to a valid value (e.g. ``ro``)
428 If you want instead to have the instance boot from its disk (and execute
429 its bootloader), simply set the ``kernel_path`` parameter to an empty
430 string, and all the others will be ignored.
435 .. note:: This section only applies to multi-node clusters
437 .. _instance-change-primary-label:
439 Changing the primary node
440 +++++++++++++++++++++++++
442 There are three ways to exchange an instance's primary and secondary
443 nodes; the right one to choose depends on how the instance has been
444 created and the status of its current primary node. See
445 :ref:`rest-redundancy-label` for information on changing the secondary
446 node. Note that it's only possible to change the primary node to the
447 secondary and vice-versa; a direct change of the primary node with a
448 third node, while keeping the current secondary is not possible in a
449 single step, only via multiple operations as detailed in
450 :ref:`instance-relocation-label`.
452 Failing over an instance
453 ~~~~~~~~~~~~~~~~~~~~~~~~
455 If an instance is built in highly available mode you can at any time
456 fail it over to its secondary node, even if the primary has somehow
457 failed and it's not up anymore. Doing it is really easy, on the master
458 node you can just run::
460 gnt-instance failover INSTANCE_NAME
462 That's it. After the command completes the secondary node is now the
463 primary, and vice-versa.
465 Live migrating an instance
466 ~~~~~~~~~~~~~~~~~~~~~~~~~~
468 If an instance is built in highly available mode, it currently runs and
469 both its nodes are running fine, you can at migrate it over to its
470 secondary node, without downtime. On the master node you need to run::
472 gnt-instance migrate INSTANCE_NAME
474 The current load on the instance and its memory size will influence how
475 long the migration will take. In any case, for both KVM and Xen
476 hypervisors, the migration will be transparent to the instance.
478 Moving an instance (offline)
479 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
481 If an instance has not been create as mirrored, then the only way to
482 change its primary node is to execute the move command::
484 gnt-instance move -n NEW_NODE INSTANCE
486 This has a few prerequisites:
488 - the instance must be stopped
489 - its current primary node must be on-line and healthy
490 - the disks of the instance must not have any errors
492 Since this operation actually copies the data from the old node to the
493 new node, expect it to take proportional to the size of the instance's
494 disks and the speed of both the nodes' I/O system and their networking.
499 Disk failures are a common cause of errors in any server
500 deployment. Ganeti offers protection from single-node failure if your
501 instances were created in HA mode, and it also offers ways to restore
502 redundancy after a failure.
504 Preparing for disk operations
505 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
507 It is important to note that for Ganeti to be able to do any disk
508 operation, the Linux machines on top of which Ganeti must be consistent;
509 for LVM, this means that the LVM commands must not return failures; it
510 is common that after a complete disk failure, any LVM command aborts
511 with an error similar to::
514 /dev/sdb1: read failed after 0 of 4096 at 0: Input/output error
515 /dev/sdb1: read failed after 0 of 4096 at 750153695232: Input/output
517 /dev/sdb1: read failed after 0 of 4096 at 0: Input/output error
518 Couldn't find device with uuid
519 't30jmN-4Rcf-Fr5e-CURS-pawt-z0jU-m1TgeJ'.
520 Couldn't find all physical volumes for volume group xenvg.
522 Before restoring an instance's disks to healthy status, it's needed to
523 fix the volume group used by Ganeti so that we can actually create and
524 manage the logical volumes. This is usually done in a multi-step
527 #. first, if the disk is completely gone and LVM commands exit with
528 “Couldn't find device with uuid…” then you need to run the command::
530 vgreduce --removemissing VOLUME_GROUP
532 #. after the above command, the LVM commands should be executing
533 normally (warnings are normal, but the commands will not fail
536 #. if the failed disk is still visible in the output of the ``pvs``
537 command, you need to deactivate it from allocations by running::
541 At this point, the volume group should be consistent and any bad
542 physical volumes should not longer be available for allocation.
544 Note that since version 2.1 Ganeti provides some commands to automate
545 these two operations, see :ref:`storage-units-label`.
547 .. _rest-redundancy-label:
549 Restoring redundancy for DRBD-based instances
550 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
552 A DRBD instance has two nodes, and the storage on one of them has
553 failed. Depending on which node (primary or secondary) has failed, you
554 have three options at hand:
556 - if the storage on the primary node has failed, you need to re-create
558 - if the storage on the secondary node has failed, you can either
559 re-create the disks on it or change the secondary and recreate
560 redundancy on the new secondary node
562 Of course, at any point it's possible to force re-creation of disks even
563 though everything is already fine.
565 For all three cases, the ``replace-disks`` operation can be used::
567 # re-create disks on the primary node
568 gnt-instance replace-disks -p INSTANCE_NAME
569 # re-create disks on the current secondary
570 gnt-instance replace-disks -s INSTANCE_NAME
571 # change the secondary node, via manual specification
572 gnt-instance replace-disks -n NODE INSTANCE_NAME
573 # change the secondary node, via an iallocator script
574 gnt-instance replace-disks -I SCRIPT INSTANCE_NAME
575 # since Ganeti 2.1: automatically fix the primary or secondary node
576 gnt-instance replace-disks -a INSTANCE_NAME
578 Since the process involves copying all data from the working node to the
579 target node, it will take a while, depending on the instance's disk
580 size, node I/O system and network speed. But it is (baring any network
581 interruption) completely transparent for the instance.
583 Re-creating disks for non-redundant instances
584 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
586 .. versionadded:: 2.1
588 For non-redundant instances, there isn't a copy (except backups) to
589 re-create the disks. But it's possible to at-least re-create empty
590 disks, after which a reinstall can be run, via the ``recreate-disks``
593 gnt-instance recreate-disks INSTANCE
595 Note that this will fail if the disks already exists.
597 Conversion of an instance's disk type
598 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
600 It is possible to convert between a non-redundant instance of type
601 ``plain`` (LVM storage) and redundant ``drbd`` via the ``gnt-instance
604 # start with a non-redundant instance
605 gnt-instance add -t plain ... INSTANCE
607 # later convert it to redundant
608 gnt-instance stop INSTANCE
609 gnt-instance modify -t drbd -n NEW_SECONDARY INSTANCE
610 gnt-instance start INSTANCE
612 # and convert it back
613 gnt-instance stop INSTANCE
614 gnt-instance modify -t plain INSTANCE
615 gnt-instance start INSTANCE
617 The conversion must be done while the instance is stopped, and
618 converting from plain to drbd template presents a small risk, especially
619 if the instance has multiple disks and/or if one node fails during the
620 conversion procedure). As such, it's recommended (as always) to make
621 sure that downtime for manual recovery is acceptable and that the
622 instance has up-to-date backups.
627 Accessing an instance's disks
628 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
630 From an instance's primary node you can have access to its disks. Never
631 ever mount the underlying logical volume manually on a fault tolerant
632 instance, or will break replication and your data will be
633 inconsistent. The correct way to access an instance's disks is to run
634 (on the master node, as usual) the command::
636 gnt-instance activate-disks INSTANCE
638 And then, *on the primary node of the instance*, access the device that
639 gets created. For example, you could mount the given disks, then edit
640 files on the filesystem, etc.
642 Note that with partitioned disks (as opposed to whole-disk filesystems),
643 you will need to use a tool like :manpage:`kpartx(8)`::
645 node1# gnt-instance activate-disks instance1
648 node3# kpartx -l /dev/…
649 node3# kpartx -a /dev/…
650 node3# mount /dev/mapper/… /mnt/
651 # edit files under mnt as desired
653 node3# kpartx -d /dev/…
657 After you've finished you can deactivate them with the deactivate-disks
658 command, which works in the same way::
660 gnt-instance deactivate-disks INSTANCE
662 Note that if any process started by you is still using the disks, the
663 above command will error out, and you **must** cleanup and ensure that
664 the above command runs successfully before you start the instance,
665 otherwise the instance will suffer corruption.
667 Accessing an instance's console
668 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
670 The command to access a running instance's console is::
672 gnt-instance console INSTANCE_NAME
674 Use the console normally and then type ``^]`` when done, to exit.
676 Other instance operations
677 +++++++++++++++++++++++++
682 There is a wrapper command for rebooting instances::
684 gnt-instance reboot instance2
686 By default, this does the equivalent of shutting down and then starting
687 the instance, but it accepts parameters to perform a soft-reboot (via
688 the hypervisor), a hard reboot (hypervisor shutdown and then startup) or
689 a full one (the default, which also de-configures and then configures
690 again the disks of the instance).
692 Instance OS definitions debugging
693 +++++++++++++++++++++++++++++++++
695 Should you have any problems with instance operating systems the command
696 to see a complete status for all your nodes is::
700 .. _instance-relocation-label:
705 While it is not possible to move an instance from nodes ``(A, B)`` to
706 nodes ``(C, D)`` in a single move, it is possible to do so in a few
709 # instance is located on A, B
710 node1# gnt-instance replace -n nodeC instance1
711 # instance has moved from (A, B) to (A, C)
712 # we now flip the primary/secondary nodes
713 node1# gnt-instance migrate instance1
714 # instance lives on (C, A)
715 # we can then change A to D via:
716 node1# gnt-instance replace -n nodeD instance1
718 Which brings it into the final configuration of ``(C, D)``. Note that we
719 needed to do two replace-disks operation (two copies of the instance
720 disks), because we needed to get rid of both the original nodes (A and
726 There are much fewer node operations available than for instances, but
727 they are equivalently important for maintaining a healthy cluster.
732 It is at any time possible to extend the cluster with one more node, by
733 using the node add operation::
735 gnt-node add NEW_NODE
737 If the cluster has a replication network defined, then you need to pass
738 the ``-s REPLICATION_IP`` parameter to this option.
740 A variation of this command can be used to re-configure a node if its
741 Ganeti configuration is broken, for example if it has been reinstalled
744 gnt-node add --readd EXISTING_NODE
746 This will reinitialise the node as if it's been newly added, but while
747 keeping its existing configuration in the cluster (primary/secondary IP,
748 etc.), in other words you won't need to use ``-s`` here.
750 Changing the node role
751 ++++++++++++++++++++++
753 A node can be in different roles, as explained in the
754 :ref:`terminology-label` section. Promoting a node to the master role is
755 special, while the other roles are handled all via a single command.
757 Failing over the master node
758 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
760 If you want to promote a different node to the master role (for whatever
761 reason), run on any other master-candidate node the command::
763 gnt-cluster master-failover
765 and the node you ran it on is now the new master. In case you try to run
766 this on a non master-candidate node, you will get an error telling you
767 which nodes are valid.
769 Changing between the other roles
770 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
772 The ``gnt-node modify`` command can be used to select a new role::
774 # change to master candidate
775 gnt-node modify -C yes NODE
776 # change to drained status
777 gnt-node modify -D yes NODE
778 # change to offline status
779 gnt-node modify -O yes NODE
780 # change to regular mode (reset all flags)
781 gnt-node modify -O no -D no -C no NODE
783 Note that the cluster requires that at any point in time, a certain
784 number of nodes are master candidates, so changing from master candidate
785 to other roles might fail. It is recommended to either force the
786 operation (via the ``--force`` option) or first change the number of
787 master candidates in the cluster - see :ref:`cluster-config-label`.
792 There are two steps of moving instances off a node:
794 - moving the primary instances (actually converting them into secondary
796 - moving the secondary instances (including any instances converted in
799 Primary instance conversion
800 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
802 For this step, you can use either individual instance move
803 commands (as seen in :ref:`instance-change-primary-label`) or the bulk
804 per-node versions; these are::
806 gnt-node migrate NODE
807 gnt-node evacuate NODE
809 Note that the instance “move” command doesn't currently have a node
812 Both these commands, or the equivalent per-instance command, will make
813 this node the secondary node for the respective instances, whereas their
814 current secondary node will become primary. Note that it is not possible
815 to change in one step the primary node to another node as primary, while
816 keeping the same secondary node.
818 Secondary instance evacuation
819 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
821 For the evacuation of secondary instances, a command called
822 :command:`gnt-node evacuate` is provided and its syntax is::
824 gnt-node evacuate -I IALLOCATOR_SCRIPT NODE
825 gnt-node evacuate -n DESTINATION_NODE NODE
827 The first version will compute the new secondary for each instance in
828 turn using the given iallocator script, whereas the second one will
829 simply move all instances to DESTINATION_NODE.
834 Once a node no longer has any instances (neither primary nor secondary),
835 it's easy to remove it from the cluster::
837 gnt-node remove NODE_NAME
839 This will deconfigure the node, stop the ganeti daemons on it and leave
840 it hopefully like before it joined to the cluster.
845 When using LVM (either standalone or with DRBD), it can become tedious
846 to debug and fix it in case of errors. Furthermore, even file-based
847 storage can become complicated to handle manually on many hosts. Ganeti
848 provides a couple of commands to help with automation.
853 This is a command specific to LVM handling. It allows listing the
854 logical volumes on a given node or on all nodes and their association to
855 instances via the ``volumes`` command::
857 node1# gnt-node volumes
858 Node PhysDev VG Name Size Instance
859 node1 /dev/sdb1 xenvg e61fbc97-….disk0 512M instance17
860 node1 /dev/sdb1 xenvg ebd1a7d1-….disk0 512M instance19
861 node2 /dev/sdb1 xenvg 0af08a3d-….disk0 512M instance20
862 node2 /dev/sdb1 xenvg cc012285-….disk0 512M instance16
863 node2 /dev/sdb1 xenvg f0fac192-….disk0 512M instance18
865 The above command maps each logical volume to a volume group and
866 underlying physical volume and (possibly) to an instance.
868 .. _storage-units-label:
870 Generalized storage handling
871 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
873 .. versionadded:: 2.1
875 Starting with Ganeti 2.1, a new storage framework has been implemented
876 that tries to abstract the handling of the storage type the cluster
879 First is listing the backend storage and their space situation::
881 node1# gnt-node list-storage
882 Node Name Size Used Free
883 node1 /dev/sda7 673.8G 0M 673.8G
884 node1 /dev/sdb1 698.6G 1.5G 697.1G
885 node2 /dev/sda7 673.8G 0M 673.8G
886 node2 /dev/sdb1 698.6G 1.0G 697.6G
888 The default is to list LVM physical volumes. It's also possible to list
889 the LVM volume groups::
891 node1# gnt-node list-storage -t lvm-vg
896 Next is repairing storage units, which is currently only implemented for
897 volume groups and does the equivalent of ``vgreduce --removemissing``::
899 node1# gnt-node repair-storage node2 lvm-vg xenvg
900 Sun Oct 25 22:21:45 2009 Repairing storage unit 'xenvg' on node2 ...
902 Last is the modification of volume properties, which is (again) only
903 implemented for LVM physical volumes and allows toggling the
904 ``allocatable`` value::
906 node1# gnt-node modify-storage --allocatable=no node2 lvm-pv /dev/sdb1
908 Use of the storage commands
909 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
911 All these commands are needed when recovering a node from a disk
914 - first, we need to recover from complete LVM failure (due to missing
915 disk), by running the ``repair-storage`` command
916 - second, we need to change allocation on any partially-broken disk
917 (i.e. LVM still sees it, but it has bad blocks) by running
919 - then we can evacuate the instances as needed
925 Beside the cluster initialisation command (which is detailed in the
926 :doc:`install` document) and the master failover command which is
927 explained under node handling, there are a couple of other cluster
928 operations available.
930 .. _cluster-config-label:
935 One of the few commands that can be run on any node (not only the
936 master) is the ``getmaster`` command::
938 node2# gnt-cluster getmaster
942 It is possible to query and change global cluster parameters via the
943 ``info`` and ``modify`` commands::
945 node1# gnt-cluster info
946 Cluster name: cluster.example.com
947 Cluster UUID: 07805e6f-f0af-4310-95f1-572862ee939c
948 Creation time: 2009-09-25 05:04:15
949 Modification time: 2009-10-18 22:11:47
950 Master node: node1.example.com
951 Architecture (this node): 64bit (x86_64)
954 Default hypervisor: xen-pvm
955 Enabled hypervisors: xen-pvm
956 Hypervisor parameters:
961 - candidate pool size: 10
963 Default instance parameters:
967 Default nic parameters:
972 There various parameters above can be changed via the ``modify``
975 - the hypervisor parameters can be changed via ``modify -H
976 xen-pvm:root_path=…``, and so on for other hypervisors/key/values
977 - the "default instance parameters" are changeable via ``modify -B
978 parameter=value…`` syntax
979 - the cluster parameters are changeable via separate options to the
980 modify command (e.g. ``--candidate-pool-size``, etc.)
982 For detailed option list see the :manpage:`gnt-cluster(8)` man page.
984 The cluster version can be obtained via the ``version`` command::
985 node1# gnt-cluster version
986 Software version: 2.1.0
987 Internode protocol: 20
988 Configuration format: 2010000
992 This is not very useful except when debugging Ganeti.
997 There are two commands provided for replicating files to all nodes of a
998 cluster and for running commands on all the nodes::
1000 node1# gnt-cluster copyfile /path/to/file
1001 node1# gnt-cluster command ls -l /path/to/file
1003 These are simple wrappers over scp/ssh and more advanced usage can be
1004 obtained using :manpage:`dsh(1)` and similar commands. But they are
1005 useful to update an OS script from the master node, for example.
1007 Cluster verification
1008 ++++++++++++++++++++
1010 There are three commands that relate to global cluster checks. The first
1011 one is ``verify`` which gives an overview on the cluster state,
1012 highlighting any issues. In normal operation, this command should return
1013 no ``ERROR`` messages::
1015 node1# gnt-cluster verify
1016 Sun Oct 25 23:08:58 2009 * Verifying global settings
1017 Sun Oct 25 23:08:58 2009 * Gathering data (2 nodes)
1018 Sun Oct 25 23:09:00 2009 * Verifying node status
1019 Sun Oct 25 23:09:00 2009 * Verifying instance status
1020 Sun Oct 25 23:09:00 2009 * Verifying orphan volumes
1021 Sun Oct 25 23:09:00 2009 * Verifying remaining instances
1022 Sun Oct 25 23:09:00 2009 * Verifying N+1 Memory redundancy
1023 Sun Oct 25 23:09:00 2009 * Other Notes
1024 Sun Oct 25 23:09:00 2009 - NOTICE: 5 non-redundant instance(s) found.
1025 Sun Oct 25 23:09:00 2009 * Hooks Results
1027 The second command is ``verify-disks``, which checks that the instance's
1028 disks have the correct status based on the desired instance state
1031 node1# gnt-cluster verify-disks
1033 Note that this command will show no output when disks are healthy.
1035 The last command is used to repair any discrepancies in Ganeti's
1036 recorded disk size and the actual disk size (disk size information is
1037 needed for proper activation and growth of DRBD-based disks)::
1039 node1# gnt-cluster repair-disk-sizes
1040 Sun Oct 25 23:13:16 2009 - INFO: Disk 0 of instance instance1 has mismatched size, correcting: recorded 512, actual 2048
1041 Sun Oct 25 23:13:17 2009 - WARNING: Invalid result from node node4, ignoring node results
1043 The above shows one instance having wrong disk size, and a node which
1044 returned invalid data, and thus we ignored all primary instances of that
1047 Configuration redistribution
1048 ++++++++++++++++++++++++++++
1050 If the verify command complains about file mismatches between the master
1051 and other nodes, due to some node problems or if you manually modified
1052 configuration files, you can force an push of the master configuration
1053 to all other nodes via the ``redist-conf`` command::
1055 node1# gnt-cluster redist-conf
1058 This command will be silent unless there are problems sending updates to
1065 It is possible to rename a cluster, or to change its IP address, via the
1066 ``rename`` command. If only the IP has changed, you need to pass the
1067 current name and Ganeti will realise its IP has changed::
1069 node1# gnt-cluster rename cluster.example.com
1070 This will rename the cluster to 'cluster.example.com'. If
1071 you are connected over the network to the cluster name, the operation
1072 is very dangerous as the IP address will be removed from the node and
1073 the change may not go through. Continue?
1075 Failure: prerequisites not met for this operation:
1076 Neither the name nor the IP address of the cluster has changed
1078 In the above output, neither value has changed since the cluster
1079 initialisation so the operation is not completed.
1084 The job queue execution in Ganeti 2.0 and higher can be inspected,
1085 suspended and resumed via the ``queue`` command::
1087 node1~# gnt-cluster queue info
1088 The drain flag is unset
1089 node1~# gnt-cluster queue drain
1090 node1~# gnt-instance stop instance1
1091 Failed to submit job for instance1: Job queue is drained, refusing job
1092 node1~# gnt-cluster queue info
1093 The drain flag is set
1094 node1~# gnt-cluster queue undrain
1096 This is most useful if you have an active cluster and you need to
1097 upgrade the Ganeti software, or simply restart the software on any node:
1099 #. suspend the queue via ``queue drain``
1100 #. wait until there are no more running jobs via ``gnt-job list``
1101 #. restart the master or another node, or upgrade the software
1102 #. resume the queue via ``queue undrain``
1104 .. note:: this command only stores a local flag file, and if you
1105 failover the master, it will not have effect on the new master.
1111 The :manpage:`ganeti-watcher` is a program, usually scheduled via
1112 ``cron``, that takes care of cluster maintenance operations (restarting
1113 downed instances, activating down DRBD disks, etc.). However, during
1114 maintenance and troubleshooting, this can get in your way; disabling it
1115 via commenting out the cron job is not so good as this can be
1116 forgotten. Thus there are some commands for automated control of the
1117 watcher: ``pause``, ``info`` and ``continue``::
1119 node1~# gnt-cluster watcher info
1120 The watcher is not paused.
1121 node1~# gnt-cluster watcher pause 1h
1122 The watcher is paused until Mon Oct 26 00:30:37 2009.
1123 node1~# gnt-cluster watcher info
1124 The watcher is paused until Mon Oct 26 00:30:37 2009.
1125 node1~# ganeti-watcher -d
1126 2009-10-25 23:30:47,984: pid=28867 ganeti-watcher:486 DEBUG Pause has been set, exiting
1127 node1~# gnt-cluster watcher continue
1128 The watcher is no longer paused.
1129 node1~# ganeti-watcher -d
1130 2009-10-25 23:31:04,789: pid=28976 ganeti-watcher:345 DEBUG Archived 0 jobs, left 0
1131 2009-10-25 23:31:05,884: pid=28976 ganeti-watcher:280 DEBUG Got data from cluster, writing instance status file
1132 2009-10-25 23:31:06,061: pid=28976 ganeti-watcher:150 DEBUG Data didn't change, just touching status file
1133 node1~# gnt-cluster watcher info
1134 The watcher is not paused.
1137 The exact details of the argument to the ``pause`` command are available
1140 .. note:: this command only stores a local flag file, and if you
1141 failover the master, it will not have effect on the new master.
1143 Node auto-maintenance
1144 +++++++++++++++++++++
1146 If the cluster parameter ``maintain_node_health`` is enabled (see the
1147 manpage for :command:`gnt-cluster`, the init and modify subcommands),
1148 then the following will happen automatically:
1150 - the watcher will shutdown any instances running on offline nodes
1151 - the watcher will deactivate any DRBD devices on offline nodes
1153 In the future, more actions are planned, so only enable this parameter
1154 if the nodes are completely dedicated to Ganeti; otherwise it might be
1155 possible to lose data due to auto-maintenance actions.
1157 Removing a cluster entirely
1158 +++++++++++++++++++++++++++
1160 The usual method to cleanup a cluster is to run ``gnt-cluster destroy``
1161 however if the Ganeti installation is broken in any way then this will
1164 It is possible in such a case to cleanup manually most if not all traces
1165 of a cluster installation by following these steps on all of the nodes:
1167 1. Shutdown all instances. This depends on the virtualisation method
1168 used (Xen, KVM, etc.):
1170 - Xen: run ``xm list`` and ``xm destroy`` on all the non-Domain-0
1172 - KVM: kill all the KVM processes
1173 - chroot: kill all processes under the chroot mountpoints
1175 2. If using DRBD, shutdown all DRBD minors (which should by at this time
1176 no-longer in use by instances); on each node, run ``drbdsetup
1177 /dev/drbdN down`` for each active DRBD minor.
1179 3. If using LVM, cleanup the Ganeti volume group; if only Ganeti created
1180 logical volumes (and you are not sharing the volume group with the
1181 OS, for example), then simply running ``lvremove -f xenvg`` (replace
1182 'xenvg' with your volume group name) should do the required cleanup.
1184 4. If using file-based storage, remove recursively all files and
1185 directories under your file-storage directory: ``rm -rf
1186 /srv/ganeti/file-storage/*`` replacing the path with the correct path
1189 5. Stop the ganeti daemons (``/etc/init.d/ganeti stop``) and kill any
1190 that remain alive (``pgrep ganeti`` and ``pkill ganeti``).
1192 6. Remove the ganeti state directory (``rm -rf /var/lib/ganeti/*``),
1193 replacing the path with the correct path for your installation.
1195 On the master node, remove the cluster from the master-netdev (usually
1196 ``xen-br0`` for bridged mode, otherwise ``eth0`` or similar), by running
1197 ``ip a del $clusterip/32 dev xen-br0`` (use the correct cluster ip and
1198 network device name).
1200 At this point, the machines are ready for a cluster creation; in case
1201 you want to remove Ganeti completely, you need to also undo some of the
1202 SSH changes and log directories:
1204 - ``rm -rf /var/log/ganeti /srv/ganeti`` (replace with the correct
1206 - remove from ``/root/.ssh`` the keys that Ganeti added (check the
1207 ``authorized_keys`` and ``id_dsa`` files)
1208 - regenerate the host's SSH keys (check the OpenSSH startup scripts)
1211 Otherwise, if you plan to re-create the cluster, you can just go ahead
1212 and rerun ``gnt-cluster init``.
1217 The tags handling (addition, removal, listing) is similar for all the
1218 objects that support it (instances, nodes, and the cluster).
1223 Note that the set of characters present in a tag and the maximum tag
1224 length are restricted. Currently the maximum length is 128 characters,
1225 there can be at most 4096 tags per object, and the set of characters is
1226 comprised by alphanumeric characters and additionally ``.+*/:@-``.
1231 Tags can be added via ``add-tags``::
1233 gnt-instance add-tags INSTANCE a b c
1234 gnt-node add-tags INSTANCE a b c
1235 gnt-cluster add-tags a b c
1238 The above commands add three tags to an instance, to a node and to the
1239 cluster. Note that the cluster command only takes tags as arguments,
1240 whereas the node and instance commands first required the node and
1243 Tags can also be added from a file, via the ``--from=FILENAME``
1244 argument. The file is expected to contain one tag per line.
1246 Tags can also be remove via a syntax very similar to the add one::
1248 gnt-instance remove-tags INSTANCE a b c
1252 gnt-instance list-tags
1254 gnt-cluster list-tags
1259 It is also possible to execute a global search on the all tags defined
1260 in the cluster configuration, via a cluster command::
1262 gnt-cluster search-tags REGEXP
1264 The parameter expected is a regular expression (see
1265 :manpage:`regex(7)`). This will return all tags that match the search,
1266 together with the object they are defined in (the names being show in a
1267 hierarchical kind of way)::
1269 node1# gnt-cluster search-tags o
1271 /instances/instance1 owner:bar
1277 The various jobs submitted by the instance/node/cluster commands can be
1278 examined, canceled and archived by various invocations of the
1279 ``gnt-job`` command.
1281 First is the job list command::
1284 17771 success INSTANCE_QUERY_DATA
1285 17773 success CLUSTER_VERIFY_DISKS
1286 17775 success CLUSTER_REPAIR_DISK_SIZES
1287 17776 error CLUSTER_RENAME(cluster.example.com)
1288 17780 success CLUSTER_REDIST_CONF
1289 17792 success INSTANCE_REBOOT(instance1.example.com)
1291 More detailed information about a job can be found via the ``info``
1294 node1# gnt-job info 17776
1297 Received: 2009-10-25 23:18:02.180569
1298 Processing start: 2009-10-25 23:18:02.200335 (delta 0.019766s)
1299 Processing end: 2009-10-25 23:18:02.279743 (delta 0.079408s)
1300 Total processing time: 0.099174 seconds
1304 Processing start: 2009-10-25 23:18:02.200335
1305 Processing end: 2009-10-25 23:18:02.252282
1307 name: cluster.example.com
1310 [Neither the name nor the IP address of the cluster has changed]
1313 During the execution of a job, it's possible to follow the output of a
1314 job, similar to the log that one get from the ``gnt-`` commands, via the
1317 node1# gnt-instance add --submit … instance1
1319 node1# gnt-job watch 17818
1320 Output from job 17818 follows
1321 -----------------------------
1322 Mon Oct 26 00:22:48 2009 - INFO: Selected nodes for instance instance1 via iallocator dumb: node1, node2
1323 Mon Oct 26 00:22:49 2009 * creating instance disks...
1324 Mon Oct 26 00:22:52 2009 adding instance instance1 to cluster config
1325 Mon Oct 26 00:22:52 2009 - INFO: Waiting for instance instance1 to sync disks.
1327 Mon Oct 26 00:23:03 2009 creating os for instance instance1 on node node1
1328 Mon Oct 26 00:23:03 2009 * running the instance OS create scripts...
1329 Mon Oct 26 00:23:13 2009 * starting instance...
1332 This is useful if you need to follow a job's progress from multiple
1335 A job that has not yet started to run can be canceled::
1337 node1# gnt-job cancel 17810
1339 But not one that has already started execution::
1341 node1# gnt-job cancel 17805
1342 Job 17805 is no longer waiting in the queue
1344 There are two queues for jobs: the *current* and the *archive*
1345 queue. Jobs are initially submitted to the current queue, and they stay
1346 in that queue until they have finished execution (either successfully or
1347 not). At that point, they can be moved into the archive queue, and the
1348 ganeti-watcher script will do this automatically after 6 hours. The
1349 ganeti-cleaner script will remove the jobs from the archive directory
1352 Note that only jobs in the current queue can be viewed via the list and
1353 info commands; Ganeti itself doesn't examine the archive directory. If
1354 you need to see an older job, either move the file manually in the
1355 top-level queue directory, or look at its contents (it's a
1356 JSON-formatted file).
1358 Special Ganeti deployments
1359 --------------------------
1361 Since Ganeti 2.4, it is possible to extend the Ganeti deployment with
1362 two custom scenarios: Ganeti inside Ganeti and multi-site model.
1364 Running Ganeti under Ganeti
1365 +++++++++++++++++++++++++++
1367 It is sometimes useful to be able to use a Ganeti instance as a Ganeti
1368 node (part of another cluster, usually). One example scenario is two
1369 small clusters, where we want to have an additional master candidate
1370 that holds the cluster configuration and can be used for helping with
1371 the master voting process.
1373 However, these Ganeti instance should not host instances themselves, and
1374 should not be considered in the normal capacity planning, evacuation
1375 strategies, etc. In order to accomplish this, mark these nodes as
1376 non-``vm_capable``::
1378 node1# gnt-node modify --vm-capable=no node3
1380 The vm_capable status can be listed as usual via ``gnt-node list``::
1382 node1# gnt-node list -oname,vm_capable
1388 When this flag is set, the cluster will not do any operations that
1389 relate to instances on such nodes, e.g. hypervisor operations,
1390 disk-related operations, etc. Basically they will just keep the ssconf
1391 files, and if master candidates the full configuration.
1396 If Ganeti is deployed in multi-site model, with each site being a node
1397 group (so that instances are not relocated across the WAN by mistake),
1398 it is conceivable that either the WAN latency is high or that some sites
1399 have a lower reliability than others. In this case, it doesn't make
1400 sense to replicate the job information across all sites (or even outside
1401 of a “central” node group), so it should be possible to restrict which
1402 nodes can become master candidates via the auto-promotion algorithm.
1404 Ganeti 2.4 introduces for this purpose a new ``master_capable`` flag,
1405 which (when unset) prevents nodes from being marked as master
1406 candidates, either manually or automatically.
1408 As usual, the node modify operation can change this flag::
1410 node1# gnt-node modify --auto-promote --master-capable=no node3
1411 Fri Jan 7 06:23:07 2011 - INFO: Demoting from master candidate
1412 Fri Jan 7 06:23:08 2011 - INFO: Promoted nodes to master candidate role: node4
1414 - master_capable -> False
1415 - master_candidate -> False
1417 And the node list operation will list this flag::
1419 node1# gnt-node list -oname,master_capable node1 node2 node3
1425 Note that marking a node both not ``vm_capable`` and not
1426 ``master_capable`` makes the node practically unusable from Ganeti's
1427 point of view. Hence these two flags should be used probably in
1428 contrast: some nodes will be only master candidates (master_capable but
1429 not vm_capable), and other nodes will only hold instances (vm_capable
1430 but not master_capable).
1436 Beside the usual ``gnt-`` and ``ganeti-`` commands which are provided
1437 and installed in ``$prefix/sbin`` at install time, there are a couple of
1438 other tools installed which are used seldom but can be helpful in some
1444 The ``lvmstrap`` tool, introduced in :ref:`configure-lvm-label` section,
1445 has two modes of operation:
1447 - ``diskinfo`` shows the discovered disks on the system and their status
1448 - ``create`` takes all not-in-use disks and creates a volume group out
1451 .. warning:: The ``create`` argument to this command causes data-loss!
1456 The ``cfgupgrade`` tools is used to upgrade between major (and minor)
1457 Ganeti versions. Point-releases are usually transparent for the admin.
1459 More information about the upgrade procedure is listed on the wiki at
1460 http://code.google.com/p/ganeti/wiki/UpgradeNotes.
1462 There is also a script designed to upgrade from Ganeti 1.2 to 2.0,
1463 called ``cfgupgrade12``.
1468 .. note:: This command is not actively maintained; make sure you backup
1469 your configuration before using it
1471 This can be used as an alternative to direct editing of the
1472 main configuration file if Ganeti has a bug and prevents you, for
1473 example, from removing an instance or a node from the configuration
1481 .. warning:: This command will erase existing instances if given as
1484 This tool is used to exercise either the hardware of machines or
1485 alternatively the Ganeti software. It is safe to run on an existing
1486 cluster **as long as you don't pass it existing instance names**.
1488 The command will, by default, execute a comprehensive set of operations
1489 against a list of instances, these being:
1492 - disk replacement (for redundant instances)
1493 - failover and migration (for redundant instances)
1494 - move (for non-redundant instances)
1496 - add disks, remove disk
1497 - add NICs, remove NICs
1498 - export and then import
1502 - and finally removal of the test instances
1504 Executing all these operations will test that the hardware performs
1505 well: the creation, disk replace, disk add and disk growth will exercise
1506 the storage and network; the migrate command will test the memory of the
1507 systems. Depending on the passed options, it can also test that the
1508 instance OS definitions are executing properly the rename, import and
1514 This tool takes the Ganeti configuration and outputs a "sanitized"
1515 version, by randomizing or clearing:
1517 - DRBD secrets and cluster public key (always)
1518 - host names (optional)
1520 - OS names (optional)
1521 - LV names (optional, only useful for very old clusters which still have
1522 instances whose LVs are based on the instance name)
1524 By default, all optional items are activated except the LV name
1525 randomization. When passing ``--no-randomization``, which disables the
1526 optional items (i.e. just the DRBD secrets and cluster public keys are
1527 randomized), the resulting file can be used as a safety copy of the
1528 cluster config - while not trivial, the layout of the cluster can be
1529 recreated from it and if the instance disks have not been lost it
1530 permits recovery from the loss of all master candidates.
1535 See :doc:`separate documentation for move-instance <move-instance>`.
1537 .. TODO: document cluster-merge tool
1540 Other Ganeti projects
1541 ---------------------
1543 Below is a list (which might not be up-to-date) of additional projects
1544 that can be useful in a Ganeti deployment. They can be downloaded from
1545 the project site (http://code.google.com/p/ganeti/) and the repositories
1546 are also on the project git site (http://git.ganeti.org).
1551 The ``ganeti-nbma`` software is designed to allow instances to live on a
1552 separate, virtual network from the nodes, and in an environment where
1553 nodes are not guaranteed to be able to reach each other via multicasting
1554 or broadcasting. For more information see the README in the source
1560 Before Ganeti version 2.5, this was a standalone project; since that
1561 version it is integrated into the Ganeti codebase (see
1562 :doc:`install-quick` for instructions on how to enable it). If you run
1563 an older Ganeti version, you will have to download and build it
1566 For more information and installation instructions, see the README file
1567 in the source archive.
1569 .. vim: set textwidth=72 :