add block separators to bash commands
[pve-docs.git] / pvecm.adoc
1 ifdef::manvolnum[]
2 PVE({manvolnum})
3 ================
4 include::attributes.txt[]
5
6 NAME
7 ----
8
9 pvecm - Proxmox VE Cluster Manager
10
11 SYNOPSYS
12 --------
13
14 include::pvecm.1-synopsis.adoc[]
15
16 DESCRIPTION
17 -----------
18 endif::manvolnum[]
19
20 ifndef::manvolnum[]
21 Cluster Manager
22 ===============
23 include::attributes.txt[]
24 endif::manvolnum[]
25
26 The {PVE} cluster manager `pvecm` is a tool to create a group of
27 physical servers. Such a group is called a *cluster*. We use the
28 http://www.corosync.org[Corosync Cluster Engine] for reliable group
29 communication, and such clusters can consist of up to 32 physical nodes
30 (probably more, dependent on network latency).
31
32 `pvecm` can be used to create a new cluster, join nodes to a cluster,
33 leave the cluster, get status information and do various other cluster
34 related tasks. The **P**rox**m**o**x** **C**luster **F**ile **S**ystem (``pmxcfs'')
35 is used to transparently distribute the cluster configuration to all cluster
36 nodes.
37
38 Grouping nodes into a cluster has the following advantages:
39
40 * Centralized, web based management
41
42 * Multi-master clusters: each node can do all management task
43
44 * `pmxcfs`: database-driven file system for storing configuration files,
45 replicated in real-time on all nodes using `corosync`.
46
47 * Easy migration of virtual machines and containers between physical
48 hosts
49
50 * Fast deployment
51
52 * Cluster-wide services like firewall and HA
53
54
55 Requirements
56 ------------
57
58 * All nodes must be in the same network as `corosync` uses IP Multicast
59 to communicate between nodes (also see
60 http://www.corosync.org[Corosync Cluster Engine]). Corosync uses UDP
61 ports 5404 and 5405 for cluster communication.
62 +
63 NOTE: Some switches do not support IP multicast by default and must be
64 manually enabled first.
65
66 * Date and time have to be synchronized.
67
68 * SSH tunnel on TCP port 22 between nodes is used.
69
70 * If you are interested in High Availability, you need to have at
71 least three nodes for reliable quorum. All nodes should have the
72 same version.
73
74 * We recommend a dedicated NIC for the cluster traffic, especially if
75 you use shared storage.
76
77 NOTE: It is not possible to mix Proxmox VE 3.x and earlier with
78 Proxmox VE 4.0 cluster nodes.
79
80
81 Preparing Nodes
82 ---------------
83
84 First, install {PVE} on all nodes. Make sure that each node is
85 installed with the final hostname and IP configuration. Changing the
86 hostname and IP is not possible after cluster creation.
87
88 Currently the cluster creation has to be done on the console, so you
89 need to login via `ssh`.
90
91 Create the Cluster
92 ------------------
93
94 Login via `ssh` to the first {pve} node. Use a unique name for your cluster.
95 This name cannot be changed later.
96
97 hp1# pvecm create YOUR-CLUSTER-NAME
98
99 CAUTION: The cluster name is used to compute the default multicast
100 address. Please use unique cluster names if you run more than one
101 cluster inside your network.
102
103 To check the state of your cluster use:
104
105 hp1# pvecm status
106
107
108 Adding Nodes to the Cluster
109 ---------------------------
110
111 Login via `ssh` to the node you want to add.
112
113 hp2# pvecm add IP-ADDRESS-CLUSTER
114
115 For `IP-ADDRESS-CLUSTER` use the IP from an existing cluster node.
116
117 CAUTION: A new node cannot hold any VMs, because you would get
118 conflicts about identical VM IDs. Also, all existing configuration in
119 `/etc/pve` is overwritten when you join a new node to the cluster. To
120 workaround, use `vzdump` to backup and restore to a different VMID after
121 adding the node to the cluster.
122
123 To check the state of cluster:
124
125 # pvecm status
126
127 .Cluster status after adding 4 nodes
128 ----
129 hp2# pvecm status
130 Quorum information
131 ~~~~~~~~~~~~~~~~~~
132 Date: Mon Apr 20 12:30:13 2015
133 Quorum provider: corosync_votequorum
134 Nodes: 4
135 Node ID: 0x00000001
136 Ring ID: 1928
137 Quorate: Yes
138
139 Votequorum information
140 ~~~~~~~~~~~~~~~~~~~~~~
141 Expected votes: 4
142 Highest expected: 4
143 Total votes: 4
144 Quorum: 2
145 Flags: Quorate
146
147 Membership information
148 ~~~~~~~~~~~~~~~~~~~~~~
149 Nodeid Votes Name
150 0x00000001 1 192.168.15.91
151 0x00000002 1 192.168.15.92 (local)
152 0x00000003 1 192.168.15.93
153 0x00000004 1 192.168.15.94
154 ----
155
156 If you only want the list of all nodes use:
157
158 # pvecm nodes
159
160 .List nodes in a cluster
161 ----
162 hp2# pvecm nodes
163
164 Membership information
165 ~~~~~~~~~~~~~~~~~~~~~~
166 Nodeid Votes Name
167 1 1 hp1
168 2 1 hp2 (local)
169 3 1 hp3
170 4 1 hp4
171 ----
172
173 Adding Nodes With Separated Cluster Network
174 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
175
176 When adding a node to a cluster with a separated cluster network you need to
177 use the 'ringX_addr' parameters to set the nodes address on those networks:
178
179 [source,bash]
180 ----
181 pvecm add IP-ADDRESS-CLUSTER -ring0_addr IP-ADDRESS-RING0
182 ----
183
184 If you want to use the Redundant Ring Protocol you will also want to pass the
185 'ring1_addr' parameter.
186
187
188 Remove a Cluster Node
189 ---------------------
190
191 CAUTION: Read carefully the procedure before proceeding, as it could
192 not be what you want or need.
193
194 Move all virtual machines from the node. Make sure you have no local
195 data or backups you want to keep, or save them accordingly.
196
197 Log in to one remaining node via ssh. Issue a `pvecm nodes` command to
198 identify the node ID:
199
200 ----
201 hp1# pvecm status
202
203 Quorum information
204 ~~~~~~~~~~~~~~~~~~
205 Date: Mon Apr 20 12:30:13 2015
206 Quorum provider: corosync_votequorum
207 Nodes: 4
208 Node ID: 0x00000001
209 Ring ID: 1928
210 Quorate: Yes
211
212 Votequorum information
213 ~~~~~~~~~~~~~~~~~~~~~~
214 Expected votes: 4
215 Highest expected: 4
216 Total votes: 4
217 Quorum: 2
218 Flags: Quorate
219
220 Membership information
221 ~~~~~~~~~~~~~~~~~~~~~~
222 Nodeid Votes Name
223 0x00000001 1 192.168.15.91 (local)
224 0x00000002 1 192.168.15.92
225 0x00000003 1 192.168.15.93
226 0x00000004 1 192.168.15.94
227 ----
228
229 IMPORTANT: at this point you must power off the node to be removed and
230 make sure that it will not power on again (in the network) as it
231 is.
232
233 ----
234 hp1# pvecm nodes
235
236 Membership information
237 ~~~~~~~~~~~~~~~~~~~~~~
238 Nodeid Votes Name
239 1 1 hp1 (local)
240 2 1 hp2
241 3 1 hp3
242 4 1 hp4
243 ----
244
245 Log in to one remaining node via ssh. Issue the delete command (here
246 deleting node `hp4`):
247
248 hp1# pvecm delnode hp4
249
250 If the operation succeeds no output is returned, just check the node
251 list again with `pvecm nodes` or `pvecm status`. You should see
252 something like:
253
254 ----
255 hp1# pvecm status
256
257 Quorum information
258 ~~~~~~~~~~~~~~~~~~
259 Date: Mon Apr 20 12:44:28 2015
260 Quorum provider: corosync_votequorum
261 Nodes: 3
262 Node ID: 0x00000001
263 Ring ID: 1992
264 Quorate: Yes
265
266 Votequorum information
267 ~~~~~~~~~~~~~~~~~~~~~~
268 Expected votes: 3
269 Highest expected: 3
270 Total votes: 3
271 Quorum: 3
272 Flags: Quorate
273
274 Membership information
275 ~~~~~~~~~~~~~~~~~~~~~~
276 Nodeid Votes Name
277 0x00000001 1 192.168.15.90 (local)
278 0x00000002 1 192.168.15.91
279 0x00000003 1 192.168.15.92
280 ----
281
282 IMPORTANT: as said above, it is very important to power off the node
283 *before* removal, and make sure that it will *never* power on again
284 (in the existing cluster network) as it is.
285
286 If you power on the node as it is, your cluster will be screwed up and
287 it could be difficult to restore a clean cluster state.
288
289 If, for whatever reason, you want that this server joins the same
290 cluster again, you have to
291
292 * reinstall {pve} on it from scratch
293
294 * then join it, as explained in the previous section.
295
296 Separate A Node Without Reinstalling
297 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
298
299 CAUTION: This is *not* the recommended method, proceed with caution. Use the
300 above mentioned method if you're unsure.
301
302 You can also separate a node from a cluster without reinstalling it from
303 scratch. But after removing the node from the cluster it will still have
304 access to the shared storages! This must be resolved before you start removing
305 the node from the cluster. A {pve} cluster cannot share the exact same
306 storage with another cluster, as it leads to VMID conflicts.
307
308 Its suggested that you create a new storage where only the node which you want
309 to separate has access. This can be an new export on your NFS or a new Ceph
310 pool, to name a few examples. Its just important that the exact same storage
311 does not gets accessed by multiple clusters. After setting this storage up move
312 all data from the node and its VMs to it. Then you are ready to separate the
313 node from the cluster.
314
315 WARNING: Ensure all shared resources are cleanly separated! You will run into
316 conflicts and problems else.
317
318 First stop the corosync and the pve-cluster services on the node:
319 [source,bash]
320 ----
321 systemctl stop pve-cluster
322 systemctl stop corosync
323 ----
324
325 Start the cluster filesystem again in local mode:
326 [source,bash]
327 ----
328 pmxcfs -l
329 ----
330
331 Delete the corosync configuration files:
332 [source,bash]
333 ----
334 rm /etc/pve/corosync.conf
335 rm /etc/corosync/*
336 ----
337
338 You can now start the filesystem again as normal service:
339 [source,bash]
340 ----
341 killall pmxcfs
342 systemctl start pve-cluster
343 ----
344
345 The node is now separated from the cluster. You can deleted it from a remaining
346 node of the cluster with:
347 [source,bash]
348 ----
349 pvecm delnode oldnode
350 ----
351
352 If the command failed, because the remaining node in the cluster lost quorum
353 when the now separate node exited, you may set the expected votes to 1 as a workaround:
354 [source,bash]
355 ----
356 pvecm expected 1
357 ----
358
359 And the repeat the 'pvecm delnode' command.
360
361 Now switch back to the separated node, here delete all remaining files left
362 from the old cluster. This ensures that the node can be added to another
363 cluster again without problems.
364
365 [source,bash]
366 ----
367 rm /var/lib/corosync/*
368 ----
369
370 As the configuration files from the other nodes are still in the cluster
371 filesystem you may want to clean those up too. Remove simply the whole
372 directory recursive from '/etc/pve/nodes/NODENAME', but check three times that
373 you used the correct one before deleting it.
374
375 CAUTION: The nodes SSH keys are still in the 'authorized_key' file, this means
376 the nodes can still connect to each other with public key authentication. This
377 should be fixed by removing the respective keys from the
378 '/etc/pve/priv/authorized_keys' file.
379
380 Quorum
381 ------
382
383 {pve} use a quorum-based technique to provide a consistent state among
384 all cluster nodes.
385
386 [quote, from Wikipedia, Quorum (distributed computing)]
387 ____
388 A quorum is the minimum number of votes that a distributed transaction
389 has to obtain in order to be allowed to perform an operation in a
390 distributed system.
391 ____
392
393 In case of network partitioning, state changes requires that a
394 majority of nodes are online. The cluster switches to read-only mode
395 if it loses quorum.
396
397 NOTE: {pve} assigns a single vote to each node by default.
398
399 Cluster Network
400 ---------------
401
402 The cluster network is the core of a cluster. All messages sent over it have to
403 be delivered reliable to all nodes in their respective order. In {pve} this
404 part is done by corosync, an implementation of a high performance low overhead
405 high availability development toolkit. It serves our decentralized
406 configuration file system (`pmxcfs`).
407
408 [[cluster-network-requirements]]
409 Network Requirements
410 ~~~~~~~~~~~~~~~~~~~~
411 This needs a reliable network with latencies under 2 milliseconds (LAN
412 performance) to work properly. While corosync can also use unicast for
413 communication between nodes its **highly recommended** to have a multicast
414 capable network. The network should not be used heavily by other members,
415 ideally corosync runs on its own network.
416 *never* share it with network where storage communicates too.
417
418 Before setting up a cluster it is good practice to check if the network is fit
419 for that purpose.
420
421 * Ensure that all nodes are in the same subnet. This must only be true for the
422 network interfaces used for cluster communication (corosync).
423
424 * Ensure all nodes can reach each other over those interfaces, using `ping` is
425 enough for a basic test.
426
427 * Ensure that multicast works in general and a high package rates. This can be
428 done with the `omping` tool. The final "%loss" number should be < 1%.
429 [source,bash]
430 ----
431 omping -c 10000 -i 0.001 -F -q NODE1-IP NODE2-IP ...
432 ----
433
434 * Ensure that multicast communication works over an extended period of time.
435 This covers up problems where IGMP snooping is activated on the network but
436 no multicast querier is active. This test has a duration of around 10
437 minutes.
438 [source,bash]
439 ----
440 omping -c 600 -i 1 -q NODE1-IP NODE2-IP ...
441 ----
442
443 Your network is not ready for clustering if any of these test fails. Recheck
444 your network configuration. Especially switches are notorious for having
445 multicast disabled by default or IGMP snooping enabled with no IGMP querier
446 active.
447
448 In smaller cluster its also an option to use unicast if you really cannot get
449 multicast to work.
450
451 Separate Cluster Network
452 ~~~~~~~~~~~~~~~~~~~~~~~~
453
454 When creating a cluster without any parameters the cluster network is generally
455 shared with the Web UI and the VMs and its traffic. Depending on your setup
456 even storage traffic may get sent over the same network. Its recommended to
457 change that, as corosync is a time critical real time application.
458
459 Setting Up A New Network
460 ^^^^^^^^^^^^^^^^^^^^^^^^
461
462 First you have to setup a new network interface. It should be on a physical
463 separate network. Ensure that your network fulfills the
464 <<cluster-network-requirements,cluster network requirements>>.
465
466 Separate On Cluster Creation
467 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
468
469 This is possible through the 'ring0_addr' and 'bindnet0_addr' parameter of
470 the 'pvecm create' command used for creating a new cluster.
471
472 If you have setup a additional NIC with a static address on 10.10.10.1/25
473 and want to send and receive all cluster communication over this interface
474 you would execute:
475
476 [source,bash]
477 ----
478 pvecm create test --ring0_addr 10.10.10.1 --bindnet0_addr 10.10.10.0
479 ----
480
481 To check if everything is working properly execute:
482 [source,bash]
483 ----
484 systemctl status corosync
485 ----
486
487 [[separate-cluster-net-after-creation]]
488 Separate After Cluster Creation
489 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
490
491 You can do this also if you have already created a cluster and want to switch
492 its communication to another network, without rebuilding the whole cluster.
493 This change may lead to short durations of quorum loss in the cluster, as nodes
494 have to restart corosync and come up one after the other on the new network.
495
496 Check how to <<edit-corosync-conf,edit the corosync.conf file>> first.
497 The open it and you should see a file similar to:
498
499 ----
500 logging {
501 debug: off
502 to_syslog: yes
503 }
504
505 nodelist {
506
507 node {
508 name: due
509 nodeid: 2
510 quorum_votes: 1
511 ring0_addr: due
512 }
513
514 node {
515 name: tre
516 nodeid: 3
517 quorum_votes: 1
518 ring0_addr: tre
519 }
520
521 node {
522 name: uno
523 nodeid: 1
524 quorum_votes: 1
525 ring0_addr: uno
526 }
527
528 }
529
530 quorum {
531 provider: corosync_votequorum
532 }
533
534 totem {
535 cluster_name: thomas-testcluster
536 config_version: 3
537 ip_version: ipv4
538 secauth: on
539 version: 2
540 interface {
541 bindnetaddr: 192.168.30.50
542 ringnumber: 0
543 }
544
545 }
546 ----
547
548 The first you want to do is add the 'name' properties in the node entries if
549 you do not see them already. Those *must* match the node name.
550
551 Then replace the address from the 'ring0_addr' properties with the new
552 addresses. You may use plain IP addresses or also hostnames here. If you use
553 hostnames ensure that they are resolvable from all nodes.
554
555 In my example I want to switch my cluster communication to the 10.10.10.1/25
556 network. So I replace all 'ring0_addr' respectively. I also set the bindetaddr
557 in the totem section of the config to an address of the new network. It can be
558 any address from the subnet configured on the new network interface.
559
560 After you increased the 'config_version' property the new configuration file
561 should look like:
562
563 ----
564
565 logging {
566 debug: off
567 to_syslog: yes
568 }
569
570 nodelist {
571
572 node {
573 name: due
574 nodeid: 2
575 quorum_votes: 1
576 ring0_addr: 10.10.10.2
577 }
578
579 node {
580 name: tre
581 nodeid: 3
582 quorum_votes: 1
583 ring0_addr: 10.10.10.3
584 }
585
586 node {
587 name: uno
588 nodeid: 1
589 quorum_votes: 1
590 ring0_addr: 10.10.10.1
591 }
592
593 }
594
595 quorum {
596 provider: corosync_votequorum
597 }
598
599 totem {
600 cluster_name: thomas-testcluster
601 config_version: 4
602 ip_version: ipv4
603 secauth: on
604 version: 2
605 interface {
606 bindnetaddr: 10.10.10.1
607 ringnumber: 0
608 }
609
610 }
611 ----
612
613 Now after a final check whether all changed information is correct we save it
614 and see again the <<edit-corosync-conf,edit corosync.conf file>> section to
615 learn how to bring it in effect.
616
617 As our change cannot be enforced live from corosync we have to do an restart.
618
619 On a single node execute:
620 [source,bash]
621 ----
622 systemctl restart corosync
623 ----
624
625 Now check if everything is fine:
626
627 [source,bash]
628 ----
629 systemctl status corosync
630 ----
631
632 If corosync runs again correct restart corosync also on all other nodes.
633 They will then join the cluster membership one by one on the new network.
634
635 Redundant Ring Protocol
636 ~~~~~~~~~~~~~~~~~~~~~~~
637 To avoid a single point of failure you should implement counter measurements.
638 This can be on the hardware and operating system level through network bonding.
639
640 Corosync itself offers also a possibility to add redundancy through the so
641 called 'Redundant Ring Protocol'. This protocol allows running a second totem
642 ring on another network, this network should be physically separated from the
643 other rings network to actually increase availability.
644
645 RRP On Cluster Creation
646 ~~~~~~~~~~~~~~~~~~~~~~~
647
648 The 'pvecm create' command provides the additional parameters 'bindnetX_addr',
649 'ringX_addr' and 'rrp_mode', can be used for RRP configuration.
650
651 NOTE: See the <<corosync-conf-glossary,glossary>> if you do not know what each parameter means.
652
653 So if you have two networks, one on the 10.10.10.1/24 and the other on the
654 10.10.20.1/24 subnet you would execute:
655
656 [source,bash]
657 ----
658 pvecm create CLUSTERNAME -bindnet0_addr 10.10.10.1 -ring0_addr 10.10.10.1 \
659 -bindnet1_addr 10.10.20.1 -ring1_addr 10.10.20.1
660 ----
661
662 RRP On A Created Cluster
663 ~~~~~~~~~~~~~~~~~~~~~~~~
664
665 When enabling an already running cluster to use RRP you will take similar steps
666 as describe in <<separate-cluster-net-after-creation,separating the cluster
667 network>>. You just do it on another ring.
668
669 First add a new `interface` subsection in the `totem` section, set its
670 `ringnumber` property to `1`. Set the interfaces `bindnetaddr` property to an
671 address of the subnet you have configured for your new ring.
672 Further set the `rrp_mode` to `passive`, this is the only stable mode.
673
674 Then add to each node entry in the `nodelist` section its new `ring1_addr`
675 property with the nodes additional ring address.
676
677 So if you have two networks, one on the 10.10.10.1/24 and the other on the
678 10.10.20.1/24 subnet, the final configuration file should look like:
679
680 ----
681 totem {
682 cluster_name: tweak
683 config_version: 9
684 ip_version: ipv4
685 rrp_mode: passive
686 secauth: on
687 version: 2
688 interface {
689 bindnetaddr: 10.10.10.1
690 ringnumber: 0
691 }
692 interface {
693 bindnetaddr: 10.10.20.1
694 ringnumber: 1
695 }
696 }
697
698 nodelist {
699 node {
700 name: pvecm1
701 nodeid: 1
702 quorum_votes: 1
703 ring0_addr: 10.10.10.1
704 ring1_addr: 10.10.20.1
705 }
706
707 node {
708 name: pvecm2
709 nodeid: 2
710 quorum_votes: 1
711 ring0_addr: 10.10.10.2
712 ring1_addr: 10.10.20.2
713 }
714
715 [...] # other cluster nodes here
716 }
717
718 [...] # other remaining config sections here
719
720 ----
721
722 Bring it in effect like described in the <<edit-corosync-conf,edit the
723 corosync.conf file>> section.
724
725 This is a change which cannot take live in effect and needs at least a restart
726 of corosync. Recommended is a restart of the whole cluster.
727
728 If you cannot reboot the whole cluster ensure no High Availability services are
729 configured and the stop the corosync service on all nodes. After corosync is
730 stopped on all nodes start it one after the other again.
731
732 Corosync Configuration
733 ----------------------
734
735 The `/ect/pve/corosync.conf` file plays a central role in {pve} cluster. It
736 controls the cluster member ship and its network.
737 For reading more about it check the corosync.conf man page:
738 [source,bash]
739 ----
740 man corosync.conf
741 ----
742
743 For node membership you should always use the `pvecm` tool provided by {pve}.
744 You may have to edit the configuration file manually for other changes.
745 Here are a few best practice tips for doing this.
746
747 [[edit-corosync-conf]]
748 Edit corosync.conf
749 ~~~~~~~~~~~~~~~~~~
750
751 Editing the corosync.conf file can be not always straight forward. There are
752 two on each cluster, one in `/etc/pve/corosync.conf` and the other in
753 `/etc/corosync/corosync.conf`. Editing the one in our cluster file system will
754 propagate the changes to the local one, but not vice versa.
755
756 The configuration will get updated automatically as soon as the file changes.
757 This means changes which can be integrated in a running corosync will take
758 instantly effect. So you should always make a copy and edit that instead, to
759 avoid triggering some unwanted changes by an in between safe.
760
761 [source,bash]
762 ----
763 cp /etc/pve/corosync.conf /etc/pve/corosync.conf.new
764 ----
765
766 Then open the Config file with your favorite editor, `nano` and `vim.tiny` are
767 preinstalled on {pve} for example.
768
769 NOTE: Always increment the 'config_version' number on configuration changes,
770 omitting this can lead to problems.
771
772 After making the necessary changes create another copy of the current working
773 configuration file. This serves as a backup if the new configuration fails to
774 apply or makes problems in other ways.
775
776 [source,bash]
777 ----
778 cp /etc/pve/corosync.conf /etc/pve/corosync.conf.bak
779 ----
780
781 Then move the new configuration file over the old one:
782 [source,bash]
783 ----
784 mv /etc/pve/corosync.conf.new /etc/pve/corosync.conf
785 ----
786
787 You may check with the commands
788 [source,bash]
789 ----
790 systemctl status corosync
791 journalctl -b -u corosync
792 ----
793
794 If the change could applied automatically. If not you may have to restart the
795 corosync service via:
796 [source,bash]
797 ----
798 systemctl restart corosync
799 ----
800
801 On errors check the troubleshooting section below.
802
803 Troubleshooting
804 ~~~~~~~~~~~~~~~
805
806 Issue: 'quorum.expected_votes must be configured'
807 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
808
809 When corosync starts to fail and you get the following message in the system log:
810
811 ----
812 [...]
813 corosync[1647]: [QUORUM] Quorum provider: corosync_votequorum failed to initialize.
814 corosync[1647]: [SERV ] Service engine 'corosync_quorum' failed to load for reason
815 'configuration error: nodelist or quorum.expected_votes must be configured!'
816 [...]
817 ----
818
819 It means that the hostname you set for corosync 'ringX_addr' in the
820 configuration could not be resolved.
821
822
823 Write Configuration When Not Quorate
824 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
825
826 If you need to change '/etc/pve/corosync.conf' on an node with no quorum, and you
827 know what you do, use:
828 [source,bash]
829 ----
830 pvecm expected 1
831 ----
832
833 This sets the expected vote count to 1 and makes the cluster quorate. You can
834 now fix your configuration, or revert it back to the last working backup.
835
836 This is not enough if corosync cannot start anymore. Here its best to edit the
837 local copy of the corosync configuration in '/etc/corosync/corosync.conf' so
838 that corosync can start again. Ensure that on all nodes this configuration has
839 the same content to avoid split brains. If you are not sure what went wrong
840 it's best to ask the Proxmox Community to help you.
841
842
843 [[corosync-conf-glossary]]
844 Corosync Configuration Glossary
845 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
846
847 ringX_addr::
848 This names the different ring addresses for the corosync totem rings used for
849 the cluster communication.
850
851 bindnetaddr::
852 Defines to which interface the ring should bind to. It may be any address of
853 the subnet configured on the interface we want to use. In general its the
854 recommended to just use an address a node uses on this interface.
855
856 rrp_mode::
857 Specifies the mode of the redundant ring protocol and may be passive, active or
858 none. Note that use of active is highly experimental and not official
859 supported. Passive is the preferred mode, it may double the cluster
860 communication throughput and increases availability.
861
862
863 Cluster Cold Start
864 ------------------
865
866 It is obvious that a cluster is not quorate when all nodes are
867 offline. This is a common case after a power failure.
868
869 NOTE: It is always a good idea to use an uninterruptible power supply
870 (``UPS'', also called ``battery backup'') to avoid this state, especially if
871 you want HA.
872
873 On node startup, service `pve-manager` is started and waits for
874 quorum. Once quorate, it starts all guests which have the `onboot`
875 flag set.
876
877 When you turn on nodes, or when power comes back after power failure,
878 it is likely that some nodes boots faster than others. Please keep in
879 mind that guest startup is delayed until you reach quorum.
880
881
882 ifdef::manvolnum[]
883 include::pve-copyright.adoc[]
884 endif::manvolnum[]