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bde0e57d | 1 | [[chapter_pvecm]] |
d8742b0c | 2 | ifdef::manvolnum[] |
b2f242ab DM |
3 | pvecm(1) |
4 | ======== | |
5f09af76 DM |
5 | :pve-toplevel: |
6 | ||
d8742b0c DM |
7 | NAME |
8 | ---- | |
9 | ||
74026b8f | 10 | pvecm - Proxmox VE Cluster Manager |
d8742b0c | 11 | |
49a5e11c | 12 | SYNOPSIS |
d8742b0c DM |
13 | -------- |
14 | ||
15 | include::pvecm.1-synopsis.adoc[] | |
16 | ||
17 | DESCRIPTION | |
18 | ----------- | |
19 | endif::manvolnum[] | |
20 | ||
21 | ifndef::manvolnum[] | |
22 | Cluster Manager | |
23 | =============== | |
5f09af76 | 24 | :pve-toplevel: |
194d2f29 | 25 | endif::manvolnum[] |
5f09af76 | 26 | |
65a0aa49 | 27 | The {pve} cluster manager `pvecm` is a tool to create a group of |
8c1189b6 | 28 | physical servers. Such a group is called a *cluster*. We use the |
8a865621 | 29 | http://www.corosync.org[Corosync Cluster Engine] for reliable group |
fdf1dd36 TL |
30 | communication. There's no explicit limit for the number of nodes in a cluster. |
31 | In practice, the actual possible node count may be limited by the host and | |
79bb0794 | 32 | network performance. Currently (2021), there are reports of clusters (using |
fdf1dd36 | 33 | high-end enterprise hardware) with over 50 nodes in production. |
8a865621 | 34 | |
8c1189b6 | 35 | `pvecm` can be used to create a new cluster, join nodes to a cluster, |
a37d539f | 36 | leave the cluster, get status information, and do various other cluster-related |
60ed554f | 37 | tasks. The **P**rox**m**o**x** **C**luster **F**ile **S**ystem (``pmxcfs'') |
e300cf7d | 38 | is used to transparently distribute the cluster configuration to all cluster |
8a865621 DM |
39 | nodes. |
40 | ||
41 | Grouping nodes into a cluster has the following advantages: | |
42 | ||
a37d539f | 43 | * Centralized, web-based management |
8a865621 | 44 | |
6d3c0b34 | 45 | * Multi-master clusters: each node can do all management tasks |
8a865621 | 46 | |
a37d539f DW |
47 | * Use of `pmxcfs`, a database-driven file system, for storing configuration |
48 | files, replicated in real-time on all nodes using `corosync` | |
8a865621 | 49 | |
5eba0743 | 50 | * Easy migration of virtual machines and containers between physical |
8a865621 DM |
51 | hosts |
52 | ||
53 | * Fast deployment | |
54 | ||
55 | * Cluster-wide services like firewall and HA | |
56 | ||
57 | ||
58 | Requirements | |
59 | ------------ | |
60 | ||
a9e7c3aa SR |
61 | * All nodes must be able to connect to each other via UDP ports 5404 and 5405 |
62 | for corosync to work. | |
8a865621 | 63 | |
a37d539f | 64 | * Date and time must be synchronized. |
8a865621 | 65 | |
a37d539f | 66 | * An SSH tunnel on TCP port 22 between nodes is required. |
8a865621 | 67 | |
ceabe189 DM |
68 | * If you are interested in High Availability, you need to have at |
69 | least three nodes for reliable quorum. All nodes should have the | |
70 | same version. | |
8a865621 DM |
71 | |
72 | * We recommend a dedicated NIC for the cluster traffic, especially if | |
73 | you use shared storage. | |
74 | ||
a37d539f | 75 | * The root password of a cluster node is required for adding nodes. |
d4a9910f | 76 | |
8e0e0bcf FE |
77 | * Online migration of virtual machines is only supported when nodes have CPUs |
78 | from the same vendor. It might work otherwise, but this is never guaranteed. | |
79 | ||
e4b62d04 TL |
80 | NOTE: It is not possible to mix {pve} 3.x and earlier with {pve} 4.X cluster |
81 | nodes. | |
82 | ||
a37d539f DW |
83 | NOTE: While it's possible to mix {pve} 4.4 and {pve} 5.0 nodes, doing so is |
84 | not supported as a production configuration and should only be done temporarily, | |
85 | during an upgrade of the whole cluster from one major version to another. | |
8a865621 | 86 | |
a9e7c3aa SR |
87 | NOTE: Running a cluster of {pve} 6.x with earlier versions is not possible. The |
88 | cluster protocol (corosync) between {pve} 6.x and earlier versions changed | |
89 | fundamentally. The corosync 3 packages for {pve} 5.4 are only intended for the | |
90 | upgrade procedure to {pve} 6.0. | |
91 | ||
8a865621 | 92 | |
ceabe189 DM |
93 | Preparing Nodes |
94 | --------------- | |
8a865621 | 95 | |
65a0aa49 | 96 | First, install {pve} on all nodes. Make sure that each node is |
8a865621 DM |
97 | installed with the final hostname and IP configuration. Changing the |
98 | hostname and IP is not possible after cluster creation. | |
99 | ||
a37d539f | 100 | While it's common to reference all node names and their IPs in `/etc/hosts` (or |
a9e7c3aa SR |
101 | make their names resolvable through other means), this is not necessary for a |
102 | cluster to work. It may be useful however, as you can then connect from one node | |
a37d539f | 103 | to another via SSH, using the easier to remember node name (see also |
a9e7c3aa | 104 | xref:pvecm_corosync_addresses[Link Address Types]). Note that we always |
a37d539f | 105 | recommend referencing nodes by their IP addresses in the cluster configuration. |
a9e7c3aa | 106 | |
9a7396aa | 107 | |
11202f1d | 108 | [[pvecm_create_cluster]] |
6cab1704 TL |
109 | Create a Cluster |
110 | ---------------- | |
111 | ||
112 | You can either create a cluster on the console (login via `ssh`), or through | |
a37d539f | 113 | the API using the {pve} web interface (__Datacenter -> Cluster__). |
8a865621 | 114 | |
6cab1704 TL |
115 | NOTE: Use a unique name for your cluster. This name cannot be changed later. |
116 | The cluster name follows the same rules as node names. | |
3e380ce0 | 117 | |
6cab1704 | 118 | [[pvecm_cluster_create_via_gui]] |
3e380ce0 SR |
119 | Create via Web GUI |
120 | ~~~~~~~~~~~~~~~~~~ | |
121 | ||
24398259 SR |
122 | [thumbnail="screenshot/gui-cluster-create.png"] |
123 | ||
3e380ce0 | 124 | Under __Datacenter -> Cluster__, click on *Create Cluster*. Enter the cluster |
a37d539f DW |
125 | name and select a network connection from the drop-down list to serve as the |
126 | main cluster network (Link 0). It defaults to the IP resolved via the node's | |
3e380ce0 SR |
127 | hostname. |
128 | ||
663ae2bf DW |
129 | As of {pve} 6.2, up to 8 fallback links can be added to a cluster. To add a |
130 | redundant link, click the 'Add' button and select a link number and IP address | |
131 | from the respective fields. Prior to {pve} 6.2, to add a second link as | |
132 | fallback, you can select the 'Advanced' checkbox and choose an additional | |
133 | network interface (Link 1, see also xref:pvecm_redundancy[Corosync Redundancy]). | |
3e380ce0 | 134 | |
a37d539f DW |
135 | NOTE: Ensure that the network selected for cluster communication is not used for |
136 | any high traffic purposes, like network storage or live-migration. | |
6cab1704 TL |
137 | While the cluster network itself produces small amounts of data, it is very |
138 | sensitive to latency. Check out full | |
139 | xref:pvecm_cluster_network_requirements[cluster network requirements]. | |
140 | ||
141 | [[pvecm_cluster_create_via_cli]] | |
a37d539f DW |
142 | Create via the Command Line |
143 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
3e380ce0 SR |
144 | |
145 | Login via `ssh` to the first {pve} node and run the following command: | |
8a865621 | 146 | |
c15cdfba TL |
147 | ---- |
148 | hp1# pvecm create CLUSTERNAME | |
149 | ---- | |
8a865621 | 150 | |
3e380ce0 | 151 | To check the state of the new cluster use: |
8a865621 | 152 | |
c15cdfba | 153 | ---- |
8a865621 | 154 | hp1# pvecm status |
c15cdfba | 155 | ---- |
8a865621 | 156 | |
a37d539f DW |
157 | Multiple Clusters in the Same Network |
158 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
dd1aa0e0 TL |
159 | |
160 | It is possible to create multiple clusters in the same physical or logical | |
a37d539f DW |
161 | network. In this case, each cluster must have a unique name to avoid possible |
162 | clashes in the cluster communication stack. Furthermore, this helps avoid human | |
163 | confusion by making clusters clearly distinguishable. | |
dd1aa0e0 TL |
164 | |
165 | While the bandwidth requirement of a corosync cluster is relatively low, the | |
166 | latency of packages and the package per second (PPS) rate is the limiting | |
167 | factor. Different clusters in the same network can compete with each other for | |
168 | these resources, so it may still make sense to use separate physical network | |
169 | infrastructure for bigger clusters. | |
8a865621 | 170 | |
11202f1d | 171 | [[pvecm_join_node_to_cluster]] |
8a865621 | 172 | Adding Nodes to the Cluster |
ceabe189 | 173 | --------------------------- |
8a865621 | 174 | |
3e380ce0 SR |
175 | CAUTION: A node that is about to be added to the cluster cannot hold any guests. |
176 | All existing configuration in `/etc/pve` is overwritten when joining a cluster, | |
a37d539f DW |
177 | since guest IDs could otherwise conflict. As a workaround, you can create a |
178 | backup of the guest (`vzdump`) and restore it under a different ID, after the | |
179 | node has been added to the cluster. | |
3e380ce0 | 180 | |
6cab1704 TL |
181 | Join Node to Cluster via GUI |
182 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
3e380ce0 | 183 | |
24398259 SR |
184 | [thumbnail="screenshot/gui-cluster-join-information.png"] |
185 | ||
a37d539f DW |
186 | Log in to the web interface on an existing cluster node. Under __Datacenter -> |
187 | Cluster__, click the *Join Information* button at the top. Then, click on the | |
3e380ce0 SR |
188 | button *Copy Information*. Alternatively, copy the string from the 'Information' |
189 | field manually. | |
190 | ||
24398259 SR |
191 | [thumbnail="screenshot/gui-cluster-join.png"] |
192 | ||
a37d539f | 193 | Next, log in to the web interface on the node you want to add. |
3e380ce0 | 194 | Under __Datacenter -> Cluster__, click on *Join Cluster*. Fill in the |
6cab1704 TL |
195 | 'Information' field with the 'Join Information' text you copied earlier. |
196 | Most settings required for joining the cluster will be filled out | |
197 | automatically. For security reasons, the cluster password has to be entered | |
198 | manually. | |
3e380ce0 SR |
199 | |
200 | NOTE: To enter all required data manually, you can disable the 'Assisted Join' | |
201 | checkbox. | |
202 | ||
6cab1704 | 203 | After clicking the *Join* button, the cluster join process will start |
a37d539f DW |
204 | immediately. After the node has joined the cluster, its current node certificate |
205 | will be replaced by one signed from the cluster certificate authority (CA). | |
206 | This means that the current session will stop working after a few seconds. You | |
207 | then might need to force-reload the web interface and log in again with the | |
208 | cluster credentials. | |
3e380ce0 | 209 | |
6cab1704 | 210 | Now your node should be visible under __Datacenter -> Cluster__. |
3e380ce0 | 211 | |
6cab1704 TL |
212 | Join Node to Cluster via Command Line |
213 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
3e380ce0 | 214 | |
a37d539f | 215 | Log in to the node you want to join into an existing cluster via `ssh`. |
8a865621 | 216 | |
c15cdfba | 217 | ---- |
8673c878 | 218 | # pvecm add IP-ADDRESS-CLUSTER |
c15cdfba | 219 | ---- |
8a865621 | 220 | |
a37d539f | 221 | For `IP-ADDRESS-CLUSTER`, use the IP or hostname of an existing cluster node. |
a9e7c3aa | 222 | An IP address is recommended (see xref:pvecm_corosync_addresses[Link Address Types]). |
8a865621 | 223 | |
8a865621 | 224 | |
a9e7c3aa | 225 | To check the state of the cluster use: |
8a865621 | 226 | |
c15cdfba | 227 | ---- |
8a865621 | 228 | # pvecm status |
c15cdfba | 229 | ---- |
8a865621 | 230 | |
ceabe189 | 231 | .Cluster status after adding 4 nodes |
8a865621 | 232 | ---- |
8673c878 DW |
233 | # pvecm status |
234 | Cluster information | |
235 | ~~~~~~~~~~~~~~~~~~~ | |
236 | Name: prod-central | |
237 | Config Version: 3 | |
238 | Transport: knet | |
239 | Secure auth: on | |
240 | ||
8a865621 DM |
241 | Quorum information |
242 | ~~~~~~~~~~~~~~~~~~ | |
8673c878 | 243 | Date: Tue Sep 14 11:06:47 2021 |
8a865621 DM |
244 | Quorum provider: corosync_votequorum |
245 | Nodes: 4 | |
246 | Node ID: 0x00000001 | |
8673c878 | 247 | Ring ID: 1.1a8 |
8a865621 DM |
248 | Quorate: Yes |
249 | ||
250 | Votequorum information | |
251 | ~~~~~~~~~~~~~~~~~~~~~~ | |
252 | Expected votes: 4 | |
253 | Highest expected: 4 | |
254 | Total votes: 4 | |
91f3edd0 | 255 | Quorum: 3 |
8a865621 DM |
256 | Flags: Quorate |
257 | ||
258 | Membership information | |
259 | ~~~~~~~~~~~~~~~~~~~~~~ | |
260 | Nodeid Votes Name | |
261 | 0x00000001 1 192.168.15.91 | |
262 | 0x00000002 1 192.168.15.92 (local) | |
263 | 0x00000003 1 192.168.15.93 | |
264 | 0x00000004 1 192.168.15.94 | |
265 | ---- | |
266 | ||
a37d539f | 267 | If you only want a list of all nodes, use: |
8a865621 | 268 | |
c15cdfba | 269 | ---- |
8a865621 | 270 | # pvecm nodes |
c15cdfba | 271 | ---- |
8a865621 | 272 | |
5eba0743 | 273 | .List nodes in a cluster |
8a865621 | 274 | ---- |
8673c878 | 275 | # pvecm nodes |
8a865621 DM |
276 | |
277 | Membership information | |
278 | ~~~~~~~~~~~~~~~~~~~~~~ | |
279 | Nodeid Votes Name | |
280 | 1 1 hp1 | |
281 | 2 1 hp2 (local) | |
282 | 3 1 hp3 | |
283 | 4 1 hp4 | |
284 | ---- | |
285 | ||
3254bfdd | 286 | [[pvecm_adding_nodes_with_separated_cluster_network]] |
a37d539f | 287 | Adding Nodes with Separated Cluster Network |
e4ec4154 TL |
288 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
289 | ||
a37d539f | 290 | When adding a node to a cluster with a separated cluster network, you need to |
a9e7c3aa | 291 | use the 'link0' parameter to set the nodes address on that network: |
e4ec4154 TL |
292 | |
293 | [source,bash] | |
4d19cb00 | 294 | ---- |
a9e7c3aa | 295 | pvecm add IP-ADDRESS-CLUSTER -link0 LOCAL-IP-ADDRESS-LINK0 |
4d19cb00 | 296 | ---- |
e4ec4154 | 297 | |
a9e7c3aa | 298 | If you want to use the built-in xref:pvecm_redundancy[redundancy] of the |
a37d539f | 299 | Kronosnet transport layer, also use the 'link1' parameter. |
e4ec4154 | 300 | |
a37d539f DW |
301 | Using the GUI, you can select the correct interface from the corresponding |
302 | 'Link X' fields in the *Cluster Join* dialog. | |
8a865621 DM |
303 | |
304 | Remove a Cluster Node | |
ceabe189 | 305 | --------------------- |
8a865621 | 306 | |
a37d539f | 307 | CAUTION: Read the procedure carefully before proceeding, as it may |
8a865621 DM |
308 | not be what you want or need. |
309 | ||
7ec7bcee DW |
310 | Move all virtual machines from the node. Ensure that you have made copies of any |
311 | local data or backups that you want to keep. In addition, make sure to remove | |
312 | any scheduled replication jobs to the node to be removed. | |
313 | ||
314 | CAUTION: Failure to remove replication jobs to a node before removing said node | |
315 | will result in the replication job becoming irremovable. Especially note that | |
316 | replication automatically switches direction if a replicated VM is migrated, so | |
317 | by migrating a replicated VM from a node to be deleted, replication jobs will be | |
318 | set up to that node automatically. | |
319 | ||
320 | In the following example, we will remove the node hp4 from the cluster. | |
8a865621 | 321 | |
e8503c6c EK |
322 | Log in to a *different* cluster node (not hp4), and issue a `pvecm nodes` |
323 | command to identify the node ID to remove: | |
8a865621 DM |
324 | |
325 | ---- | |
8673c878 | 326 | hp1# pvecm nodes |
8a865621 DM |
327 | |
328 | Membership information | |
329 | ~~~~~~~~~~~~~~~~~~~~~~ | |
330 | Nodeid Votes Name | |
331 | 1 1 hp1 (local) | |
332 | 2 1 hp2 | |
333 | 3 1 hp3 | |
334 | 4 1 hp4 | |
335 | ---- | |
336 | ||
e8503c6c | 337 | |
a37d539f DW |
338 | At this point, you must power off hp4 and ensure that it will not power on |
339 | again (in the network) with its current configuration. | |
e8503c6c | 340 | |
a37d539f DW |
341 | IMPORTANT: As mentioned above, it is critical to power off the node |
342 | *before* removal, and make sure that it will *not* power on again | |
343 | (in the existing cluster network) with its current configuration. | |
344 | If you power on the node as it is, the cluster could end up broken, | |
345 | and it could be difficult to restore it to a functioning state. | |
e8503c6c EK |
346 | |
347 | After powering off the node hp4, we can safely remove it from the cluster. | |
8a865621 | 348 | |
c15cdfba | 349 | ---- |
8a865621 | 350 | hp1# pvecm delnode hp4 |
10da5ce1 | 351 | Killing node 4 |
c15cdfba | 352 | ---- |
8a865621 | 353 | |
249fd833 DW |
354 | NOTE: At this point, it is possible that you will receive an error message |
355 | stating `Could not kill node (error = CS_ERR_NOT_EXIST)`. This does not | |
356 | signify an actual failure in the deletion of the node, but rather a failure in | |
357 | corosync trying to kill an offline node. Thus, it can be safely ignored. | |
358 | ||
10da5ce1 DJ |
359 | Use `pvecm nodes` or `pvecm status` to check the node list again. It should |
360 | look something like: | |
8a865621 DM |
361 | |
362 | ---- | |
363 | hp1# pvecm status | |
364 | ||
8673c878 | 365 | ... |
8a865621 DM |
366 | |
367 | Votequorum information | |
368 | ~~~~~~~~~~~~~~~~~~~~~~ | |
369 | Expected votes: 3 | |
370 | Highest expected: 3 | |
371 | Total votes: 3 | |
91f3edd0 | 372 | Quorum: 2 |
8a865621 DM |
373 | Flags: Quorate |
374 | ||
375 | Membership information | |
376 | ~~~~~~~~~~~~~~~~~~~~~~ | |
377 | Nodeid Votes Name | |
378 | 0x00000001 1 192.168.15.90 (local) | |
379 | 0x00000002 1 192.168.15.91 | |
380 | 0x00000003 1 192.168.15.92 | |
381 | ---- | |
382 | ||
a9e7c3aa | 383 | If, for whatever reason, you want this server to join the same cluster again, |
a37d539f | 384 | you have to: |
8a865621 | 385 | |
a37d539f | 386 | * do a fresh install of {pve} on it, |
8a865621 DM |
387 | |
388 | * then join it, as explained in the previous section. | |
d8742b0c | 389 | |
41925ede SR |
390 | NOTE: After removal of the node, its SSH fingerprint will still reside in the |
391 | 'known_hosts' of the other nodes. If you receive an SSH error after rejoining | |
9121b45b TL |
392 | a node with the same IP or hostname, run `pvecm updatecerts` once on the |
393 | re-added node to update its fingerprint cluster wide. | |
41925ede | 394 | |
38ae8db3 | 395 | [[pvecm_separate_node_without_reinstall]] |
a37d539f | 396 | Separate a Node Without Reinstalling |
555e966b TL |
397 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
398 | ||
399 | CAUTION: This is *not* the recommended method, proceed with caution. Use the | |
a37d539f | 400 | previous method if you're unsure. |
555e966b TL |
401 | |
402 | You can also separate a node from a cluster without reinstalling it from | |
a37d539f DW |
403 | scratch. But after removing the node from the cluster, it will still have |
404 | access to any shared storage. This must be resolved before you start removing | |
555e966b | 405 | the node from the cluster. A {pve} cluster cannot share the exact same |
60ed554f | 406 | storage with another cluster, as storage locking doesn't work over the cluster |
a37d539f | 407 | boundary. Furthermore, it may also lead to VMID conflicts. |
555e966b | 408 | |
a37d539f | 409 | It's suggested that you create a new storage, where only the node which you want |
a9e7c3aa | 410 | to separate has access. This can be a new export on your NFS or a new Ceph |
a37d539f DW |
411 | pool, to name a few examples. It's just important that the exact same storage |
412 | does not get accessed by multiple clusters. After setting up this storage, move | |
413 | all data and VMs from the node to it. Then you are ready to separate the | |
3be22308 | 414 | node from the cluster. |
555e966b | 415 | |
a37d539f DW |
416 | WARNING: Ensure that all shared resources are cleanly separated! Otherwise you |
417 | will run into conflicts and problems. | |
555e966b | 418 | |
a37d539f | 419 | First, stop the corosync and pve-cluster services on the node: |
555e966b | 420 | [source,bash] |
4d19cb00 | 421 | ---- |
555e966b TL |
422 | systemctl stop pve-cluster |
423 | systemctl stop corosync | |
4d19cb00 | 424 | ---- |
555e966b | 425 | |
a37d539f | 426 | Start the cluster file system again in local mode: |
555e966b | 427 | [source,bash] |
4d19cb00 | 428 | ---- |
555e966b | 429 | pmxcfs -l |
4d19cb00 | 430 | ---- |
555e966b TL |
431 | |
432 | Delete the corosync configuration files: | |
433 | [source,bash] | |
4d19cb00 | 434 | ---- |
555e966b | 435 | rm /etc/pve/corosync.conf |
838081cd | 436 | rm -r /etc/corosync/* |
4d19cb00 | 437 | ---- |
555e966b | 438 | |
a37d539f | 439 | You can now start the file system again as a normal service: |
555e966b | 440 | [source,bash] |
4d19cb00 | 441 | ---- |
555e966b TL |
442 | killall pmxcfs |
443 | systemctl start pve-cluster | |
4d19cb00 | 444 | ---- |
555e966b | 445 | |
a37d539f DW |
446 | The node is now separated from the cluster. You can deleted it from any |
447 | remaining node of the cluster with: | |
555e966b | 448 | [source,bash] |
4d19cb00 | 449 | ---- |
555e966b | 450 | pvecm delnode oldnode |
4d19cb00 | 451 | ---- |
555e966b | 452 | |
a37d539f DW |
453 | If the command fails due to a loss of quorum in the remaining node, you can set |
454 | the expected votes to 1 as a workaround: | |
555e966b | 455 | [source,bash] |
4d19cb00 | 456 | ---- |
555e966b | 457 | pvecm expected 1 |
4d19cb00 | 458 | ---- |
555e966b | 459 | |
96d698db | 460 | And then repeat the 'pvecm delnode' command. |
555e966b | 461 | |
a37d539f DW |
462 | Now switch back to the separated node and delete all the remaining cluster |
463 | files on it. This ensures that the node can be added to another cluster again | |
464 | without problems. | |
555e966b TL |
465 | |
466 | [source,bash] | |
4d19cb00 | 467 | ---- |
555e966b | 468 | rm /var/lib/corosync/* |
4d19cb00 | 469 | ---- |
555e966b TL |
470 | |
471 | As the configuration files from the other nodes are still in the cluster | |
a37d539f DW |
472 | file system, you may want to clean those up too. After making absolutely sure |
473 | that you have the correct node name, you can simply remove the entire | |
474 | directory recursively from '/etc/pve/nodes/NODENAME'. | |
555e966b | 475 | |
a37d539f DW |
476 | CAUTION: The node's SSH keys will remain in the 'authorized_key' file. This |
477 | means that the nodes can still connect to each other with public key | |
478 | authentication. You should fix this by removing the respective keys from the | |
555e966b | 479 | '/etc/pve/priv/authorized_keys' file. |
d8742b0c | 480 | |
a9e7c3aa | 481 | |
806ef12d DM |
482 | Quorum |
483 | ------ | |
484 | ||
485 | {pve} use a quorum-based technique to provide a consistent state among | |
486 | all cluster nodes. | |
487 | ||
488 | [quote, from Wikipedia, Quorum (distributed computing)] | |
489 | ____ | |
490 | A quorum is the minimum number of votes that a distributed transaction | |
491 | has to obtain in order to be allowed to perform an operation in a | |
492 | distributed system. | |
493 | ____ | |
494 | ||
495 | In case of network partitioning, state changes requires that a | |
496 | majority of nodes are online. The cluster switches to read-only mode | |
5eba0743 | 497 | if it loses quorum. |
806ef12d DM |
498 | |
499 | NOTE: {pve} assigns a single vote to each node by default. | |
500 | ||
a9e7c3aa | 501 | |
e4ec4154 TL |
502 | Cluster Network |
503 | --------------- | |
504 | ||
505 | The cluster network is the core of a cluster. All messages sent over it have to | |
a9e7c3aa | 506 | be delivered reliably to all nodes in their respective order. In {pve} this |
a37d539f DW |
507 | part is done by corosync, an implementation of a high performance, low overhead, |
508 | high availability development toolkit. It serves our decentralized configuration | |
509 | file system (`pmxcfs`). | |
e4ec4154 | 510 | |
3254bfdd | 511 | [[pvecm_cluster_network_requirements]] |
e4ec4154 TL |
512 | Network Requirements |
513 | ~~~~~~~~~~~~~~~~~~~~ | |
514 | This needs a reliable network with latencies under 2 milliseconds (LAN | |
a9e7c3aa | 515 | performance) to work properly. The network should not be used heavily by other |
a37d539f | 516 | members; ideally corosync runs on its own network. Do not use a shared network |
a9e7c3aa SR |
517 | for corosync and storage (except as a potential low-priority fallback in a |
518 | xref:pvecm_redundancy[redundant] configuration). | |
e4ec4154 | 519 | |
a9e7c3aa | 520 | Before setting up a cluster, it is good practice to check if the network is fit |
a37d539f | 521 | for that purpose. To ensure that the nodes can connect to each other on the |
a9e7c3aa SR |
522 | cluster network, you can test the connectivity between them with the `ping` |
523 | tool. | |
e4ec4154 | 524 | |
a9e7c3aa SR |
525 | If the {pve} firewall is enabled, ACCEPT rules for corosync will automatically |
526 | be generated - no manual action is required. | |
e4ec4154 | 527 | |
a9e7c3aa SR |
528 | NOTE: Corosync used Multicast before version 3.0 (introduced in {pve} 6.0). |
529 | Modern versions rely on https://kronosnet.org/[Kronosnet] for cluster | |
530 | communication, which, for now, only supports regular UDP unicast. | |
e4ec4154 | 531 | |
a9e7c3aa SR |
532 | CAUTION: You can still enable Multicast or legacy unicast by setting your |
533 | transport to `udp` or `udpu` in your xref:pvecm_edit_corosync_conf[corosync.conf], | |
534 | but keep in mind that this will disable all cryptography and redundancy support. | |
535 | This is therefore not recommended. | |
e4ec4154 TL |
536 | |
537 | Separate Cluster Network | |
538 | ~~~~~~~~~~~~~~~~~~~~~~~~ | |
539 | ||
a37d539f DW |
540 | When creating a cluster without any parameters, the corosync cluster network is |
541 | generally shared with the web interface and the VMs' network. Depending on | |
542 | your setup, even storage traffic may get sent over the same network. It's | |
543 | recommended to change that, as corosync is a time-critical, real-time | |
a9e7c3aa | 544 | application. |
e4ec4154 | 545 | |
a37d539f | 546 | Setting Up a New Network |
e4ec4154 TL |
547 | ^^^^^^^^^^^^^^^^^^^^^^^^ |
548 | ||
9ffebff5 | 549 | First, you have to set up a new network interface. It should be on a physically |
e4ec4154 | 550 | separate network. Ensure that your network fulfills the |
3254bfdd | 551 | xref:pvecm_cluster_network_requirements[cluster network requirements]. |
e4ec4154 TL |
552 | |
553 | Separate On Cluster Creation | |
554 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | |
555 | ||
a9e7c3aa | 556 | This is possible via the 'linkX' parameters of the 'pvecm create' |
a37d539f | 557 | command, used for creating a new cluster. |
e4ec4154 | 558 | |
a9e7c3aa SR |
559 | If you have set up an additional NIC with a static address on 10.10.10.1/25, |
560 | and want to send and receive all cluster communication over this interface, | |
e4ec4154 TL |
561 | you would execute: |
562 | ||
563 | [source,bash] | |
4d19cb00 | 564 | ---- |
a9e7c3aa | 565 | pvecm create test --link0 10.10.10.1 |
4d19cb00 | 566 | ---- |
e4ec4154 | 567 | |
a37d539f | 568 | To check if everything is working properly, execute: |
e4ec4154 | 569 | [source,bash] |
4d19cb00 | 570 | ---- |
e4ec4154 | 571 | systemctl status corosync |
4d19cb00 | 572 | ---- |
e4ec4154 | 573 | |
a9e7c3aa | 574 | Afterwards, proceed as described above to |
3254bfdd | 575 | xref:pvecm_adding_nodes_with_separated_cluster_network[add nodes with a separated cluster network]. |
82d52451 | 576 | |
3254bfdd | 577 | [[pvecm_separate_cluster_net_after_creation]] |
e4ec4154 TL |
578 | Separate After Cluster Creation |
579 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | |
580 | ||
a9e7c3aa | 581 | You can do this if you have already created a cluster and want to switch |
e4ec4154 | 582 | its communication to another network, without rebuilding the whole cluster. |
a37d539f | 583 | This change may lead to short periods of quorum loss in the cluster, as nodes |
e4ec4154 TL |
584 | have to restart corosync and come up one after the other on the new network. |
585 | ||
3254bfdd | 586 | Check how to xref:pvecm_edit_corosync_conf[edit the corosync.conf file] first. |
a9e7c3aa | 587 | Then, open it and you should see a file similar to: |
e4ec4154 TL |
588 | |
589 | ---- | |
590 | logging { | |
591 | debug: off | |
592 | to_syslog: yes | |
593 | } | |
594 | ||
595 | nodelist { | |
596 | ||
597 | node { | |
598 | name: due | |
599 | nodeid: 2 | |
600 | quorum_votes: 1 | |
601 | ring0_addr: due | |
602 | } | |
603 | ||
604 | node { | |
605 | name: tre | |
606 | nodeid: 3 | |
607 | quorum_votes: 1 | |
608 | ring0_addr: tre | |
609 | } | |
610 | ||
611 | node { | |
612 | name: uno | |
613 | nodeid: 1 | |
614 | quorum_votes: 1 | |
615 | ring0_addr: uno | |
616 | } | |
617 | ||
618 | } | |
619 | ||
620 | quorum { | |
621 | provider: corosync_votequorum | |
622 | } | |
623 | ||
624 | totem { | |
a9e7c3aa | 625 | cluster_name: testcluster |
e4ec4154 | 626 | config_version: 3 |
a9e7c3aa | 627 | ip_version: ipv4-6 |
e4ec4154 TL |
628 | secauth: on |
629 | version: 2 | |
630 | interface { | |
a9e7c3aa | 631 | linknumber: 0 |
e4ec4154 TL |
632 | } |
633 | ||
634 | } | |
635 | ---- | |
636 | ||
a37d539f | 637 | NOTE: `ringX_addr` actually specifies a corosync *link address*. The name "ring" |
a9e7c3aa SR |
638 | is a remnant of older corosync versions that is kept for backwards |
639 | compatibility. | |
640 | ||
a37d539f | 641 | The first thing you want to do is add the 'name' properties in the node entries, |
a9e7c3aa | 642 | if you do not see them already. Those *must* match the node name. |
e4ec4154 | 643 | |
a9e7c3aa SR |
644 | Then replace all addresses from the 'ring0_addr' properties of all nodes with |
645 | the new addresses. You may use plain IP addresses or hostnames here. If you use | |
a37d539f DW |
646 | hostnames, ensure that they are resolvable from all nodes (see also |
647 | xref:pvecm_corosync_addresses[Link Address Types]). | |
e4ec4154 | 648 | |
a37d539f DW |
649 | In this example, we want to switch cluster communication to the |
650 | 10.10.10.1/25 network, so we change the 'ring0_addr' of each node respectively. | |
e4ec4154 | 651 | |
a9e7c3aa | 652 | NOTE: The exact same procedure can be used to change other 'ringX_addr' values |
a37d539f DW |
653 | as well. However, we recommend only changing one link address at a time, so |
654 | that it's easier to recover if something goes wrong. | |
a9e7c3aa SR |
655 | |
656 | After we increase the 'config_version' property, the new configuration file | |
e4ec4154 TL |
657 | should look like: |
658 | ||
659 | ---- | |
e4ec4154 TL |
660 | logging { |
661 | debug: off | |
662 | to_syslog: yes | |
663 | } | |
664 | ||
665 | nodelist { | |
666 | ||
667 | node { | |
668 | name: due | |
669 | nodeid: 2 | |
670 | quorum_votes: 1 | |
671 | ring0_addr: 10.10.10.2 | |
672 | } | |
673 | ||
674 | node { | |
675 | name: tre | |
676 | nodeid: 3 | |
677 | quorum_votes: 1 | |
678 | ring0_addr: 10.10.10.3 | |
679 | } | |
680 | ||
681 | node { | |
682 | name: uno | |
683 | nodeid: 1 | |
684 | quorum_votes: 1 | |
685 | ring0_addr: 10.10.10.1 | |
686 | } | |
687 | ||
688 | } | |
689 | ||
690 | quorum { | |
691 | provider: corosync_votequorum | |
692 | } | |
693 | ||
694 | totem { | |
a9e7c3aa | 695 | cluster_name: testcluster |
e4ec4154 | 696 | config_version: 4 |
a9e7c3aa | 697 | ip_version: ipv4-6 |
e4ec4154 TL |
698 | secauth: on |
699 | version: 2 | |
700 | interface { | |
a9e7c3aa | 701 | linknumber: 0 |
e4ec4154 TL |
702 | } |
703 | ||
704 | } | |
705 | ---- | |
706 | ||
a37d539f DW |
707 | Then, after a final check to see that all changed information is correct, we |
708 | save it and once again follow the | |
709 | xref:pvecm_edit_corosync_conf[edit corosync.conf file] section to bring it into | |
710 | effect. | |
e4ec4154 | 711 | |
a9e7c3aa SR |
712 | The changes will be applied live, so restarting corosync is not strictly |
713 | necessary. If you changed other settings as well, or notice corosync | |
714 | complaining, you can optionally trigger a restart. | |
e4ec4154 TL |
715 | |
716 | On a single node execute: | |
a9e7c3aa | 717 | |
e4ec4154 | 718 | [source,bash] |
4d19cb00 | 719 | ---- |
e4ec4154 | 720 | systemctl restart corosync |
4d19cb00 | 721 | ---- |
e4ec4154 | 722 | |
a37d539f | 723 | Now check if everything is okay: |
e4ec4154 TL |
724 | |
725 | [source,bash] | |
4d19cb00 | 726 | ---- |
e4ec4154 | 727 | systemctl status corosync |
4d19cb00 | 728 | ---- |
e4ec4154 | 729 | |
a37d539f | 730 | If corosync begins to work again, restart it on all other nodes too. |
e4ec4154 TL |
731 | They will then join the cluster membership one by one on the new network. |
732 | ||
3254bfdd | 733 | [[pvecm_corosync_addresses]] |
a37d539f | 734 | Corosync Addresses |
270757a1 SR |
735 | ~~~~~~~~~~~~~~~~~~ |
736 | ||
a9e7c3aa SR |
737 | A corosync link address (for backwards compatibility denoted by 'ringX_addr' in |
738 | `corosync.conf`) can be specified in two ways: | |
270757a1 | 739 | |
a37d539f | 740 | * **IPv4/v6 addresses** can be used directly. They are recommended, since they |
270757a1 SR |
741 | are static and usually not changed carelessly. |
742 | ||
a37d539f | 743 | * **Hostnames** will be resolved using `getaddrinfo`, which means that by |
270757a1 SR |
744 | default, IPv6 addresses will be used first, if available (see also |
745 | `man gai.conf`). Keep this in mind, especially when upgrading an existing | |
746 | cluster to IPv6. | |
747 | ||
a37d539f | 748 | CAUTION: Hostnames should be used with care, since the addresses they |
270757a1 SR |
749 | resolve to can be changed without touching corosync or the node it runs on - |
750 | which may lead to a situation where an address is changed without thinking | |
751 | about implications for corosync. | |
752 | ||
5f318cc0 | 753 | A separate, static hostname specifically for corosync is recommended, if |
270757a1 SR |
754 | hostnames are preferred. Also, make sure that every node in the cluster can |
755 | resolve all hostnames correctly. | |
756 | ||
757 | Since {pve} 5.1, while supported, hostnames will be resolved at the time of | |
a37d539f | 758 | entry. Only the resolved IP is saved to the configuration. |
270757a1 SR |
759 | |
760 | Nodes that joined the cluster on earlier versions likely still use their | |
761 | unresolved hostname in `corosync.conf`. It might be a good idea to replace | |
5f318cc0 | 762 | them with IPs or a separate hostname, as mentioned above. |
270757a1 | 763 | |
e4ec4154 | 764 | |
a9e7c3aa SR |
765 | [[pvecm_redundancy]] |
766 | Corosync Redundancy | |
767 | ------------------- | |
e4ec4154 | 768 | |
a37d539f | 769 | Corosync supports redundant networking via its integrated Kronosnet layer by |
a9e7c3aa SR |
770 | default (it is not supported on the legacy udp/udpu transports). It can be |
771 | enabled by specifying more than one link address, either via the '--linkX' | |
3e380ce0 SR |
772 | parameters of `pvecm`, in the GUI as **Link 1** (while creating a cluster or |
773 | adding a new node) or by specifying more than one 'ringX_addr' in | |
774 | `corosync.conf`. | |
e4ec4154 | 775 | |
a9e7c3aa SR |
776 | NOTE: To provide useful failover, every link should be on its own |
777 | physical network connection. | |
e4ec4154 | 778 | |
a9e7c3aa SR |
779 | Links are used according to a priority setting. You can configure this priority |
780 | by setting 'knet_link_priority' in the corresponding interface section in | |
5f318cc0 | 781 | `corosync.conf`, or, preferably, using the 'priority' parameter when creating |
a9e7c3aa | 782 | your cluster with `pvecm`: |
e4ec4154 | 783 | |
4d19cb00 | 784 | ---- |
fcf0226e | 785 | # pvecm create CLUSTERNAME --link0 10.10.10.1,priority=15 --link1 10.20.20.1,priority=20 |
4d19cb00 | 786 | ---- |
e4ec4154 | 787 | |
fcf0226e | 788 | This would cause 'link1' to be used first, since it has the higher priority. |
a9e7c3aa SR |
789 | |
790 | If no priorities are configured manually (or two links have the same priority), | |
791 | links will be used in order of their number, with the lower number having higher | |
792 | priority. | |
793 | ||
794 | Even if all links are working, only the one with the highest priority will see | |
a37d539f DW |
795 | corosync traffic. Link priorities cannot be mixed, meaning that links with |
796 | different priorities will not be able to communicate with each other. | |
e4ec4154 | 797 | |
a9e7c3aa | 798 | Since lower priority links will not see traffic unless all higher priorities |
a37d539f DW |
799 | have failed, it becomes a useful strategy to specify networks used for |
800 | other tasks (VMs, storage, etc.) as low-priority links. If worst comes to | |
801 | worst, a higher latency or more congested connection might be better than no | |
a9e7c3aa | 802 | connection at all. |
e4ec4154 | 803 | |
a9e7c3aa SR |
804 | Adding Redundant Links To An Existing Cluster |
805 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
e4ec4154 | 806 | |
a9e7c3aa SR |
807 | To add a new link to a running configuration, first check how to |
808 | xref:pvecm_edit_corosync_conf[edit the corosync.conf file]. | |
e4ec4154 | 809 | |
a9e7c3aa SR |
810 | Then, add a new 'ringX_addr' to every node in the `nodelist` section. Make |
811 | sure that your 'X' is the same for every node you add it to, and that it is | |
812 | unique for each node. | |
813 | ||
814 | Lastly, add a new 'interface', as shown below, to your `totem` | |
a37d539f | 815 | section, replacing 'X' with the link number chosen above. |
a9e7c3aa SR |
816 | |
817 | Assuming you added a link with number 1, the new configuration file could look | |
818 | like this: | |
e4ec4154 TL |
819 | |
820 | ---- | |
a9e7c3aa SR |
821 | logging { |
822 | debug: off | |
823 | to_syslog: yes | |
e4ec4154 TL |
824 | } |
825 | ||
826 | nodelist { | |
a9e7c3aa | 827 | |
e4ec4154 | 828 | node { |
a9e7c3aa SR |
829 | name: due |
830 | nodeid: 2 | |
e4ec4154 | 831 | quorum_votes: 1 |
a9e7c3aa SR |
832 | ring0_addr: 10.10.10.2 |
833 | ring1_addr: 10.20.20.2 | |
e4ec4154 TL |
834 | } |
835 | ||
a9e7c3aa SR |
836 | node { |
837 | name: tre | |
838 | nodeid: 3 | |
e4ec4154 | 839 | quorum_votes: 1 |
a9e7c3aa SR |
840 | ring0_addr: 10.10.10.3 |
841 | ring1_addr: 10.20.20.3 | |
e4ec4154 TL |
842 | } |
843 | ||
a9e7c3aa SR |
844 | node { |
845 | name: uno | |
846 | nodeid: 1 | |
847 | quorum_votes: 1 | |
848 | ring0_addr: 10.10.10.1 | |
849 | ring1_addr: 10.20.20.1 | |
850 | } | |
851 | ||
852 | } | |
853 | ||
854 | quorum { | |
855 | provider: corosync_votequorum | |
856 | } | |
857 | ||
858 | totem { | |
859 | cluster_name: testcluster | |
860 | config_version: 4 | |
861 | ip_version: ipv4-6 | |
862 | secauth: on | |
863 | version: 2 | |
864 | interface { | |
865 | linknumber: 0 | |
866 | } | |
867 | interface { | |
868 | linknumber: 1 | |
869 | } | |
e4ec4154 | 870 | } |
a9e7c3aa | 871 | ---- |
e4ec4154 | 872 | |
a9e7c3aa SR |
873 | The new link will be enabled as soon as you follow the last steps to |
874 | xref:pvecm_edit_corosync_conf[edit the corosync.conf file]. A restart should not | |
875 | be necessary. You can check that corosync loaded the new link using: | |
e4ec4154 | 876 | |
a9e7c3aa SR |
877 | ---- |
878 | journalctl -b -u corosync | |
e4ec4154 TL |
879 | ---- |
880 | ||
a9e7c3aa SR |
881 | It might be a good idea to test the new link by temporarily disconnecting the |
882 | old link on one node and making sure that its status remains online while | |
883 | disconnected: | |
e4ec4154 | 884 | |
a9e7c3aa SR |
885 | ---- |
886 | pvecm status | |
887 | ---- | |
888 | ||
889 | If you see a healthy cluster state, it means that your new link is being used. | |
e4ec4154 | 890 | |
e4ec4154 | 891 | |
65a0aa49 | 892 | Role of SSH in {pve} Clusters |
9d999d1b | 893 | ----------------------------- |
39aa8892 | 894 | |
65a0aa49 | 895 | {pve} utilizes SSH tunnels for various features. |
39aa8892 | 896 | |
4e8fe2a9 | 897 | * Proxying console/shell sessions (node and guests) |
9d999d1b | 898 | + |
4e8fe2a9 FG |
899 | When using the shell for node B while being connected to node A, connects to a |
900 | terminal proxy on node A, which is in turn connected to the login shell on node | |
901 | B via a non-interactive SSH tunnel. | |
39aa8892 | 902 | |
4e8fe2a9 FG |
903 | * VM and CT memory and local-storage migration in 'secure' mode. |
904 | + | |
a37d539f | 905 | During the migration, one or more SSH tunnel(s) are established between the |
4e8fe2a9 FG |
906 | source and target nodes, in order to exchange migration information and |
907 | transfer memory and disk contents. | |
9d999d1b TL |
908 | |
909 | * Storage replication | |
39aa8892 | 910 | |
9d999d1b TL |
911 | .Pitfalls due to automatic execution of `.bashrc` and siblings |
912 | [IMPORTANT] | |
913 | ==== | |
914 | In case you have a custom `.bashrc`, or similar files that get executed on | |
915 | login by the configured shell, `ssh` will automatically run it once the session | |
916 | is established successfully. This can cause some unexpected behavior, as those | |
a37d539f DW |
917 | commands may be executed with root permissions on any of the operations |
918 | described above. This can cause possible problematic side-effects! | |
39aa8892 OB |
919 | |
920 | In order to avoid such complications, it's recommended to add a check in | |
921 | `/root/.bashrc` to make sure the session is interactive, and only then run | |
922 | `.bashrc` commands. | |
923 | ||
924 | You can add this snippet at the beginning of your `.bashrc` file: | |
925 | ||
926 | ---- | |
9d999d1b | 927 | # Early exit if not running interactively to avoid side-effects! |
39aa8892 OB |
928 | case $- in |
929 | *i*) ;; | |
930 | *) return;; | |
931 | esac | |
932 | ---- | |
9d999d1b | 933 | ==== |
39aa8892 OB |
934 | |
935 | ||
c21d2cbe OB |
936 | Corosync External Vote Support |
937 | ------------------------------ | |
938 | ||
939 | This section describes a way to deploy an external voter in a {pve} cluster. | |
940 | When configured, the cluster can sustain more node failures without | |
941 | violating safety properties of the cluster communication. | |
942 | ||
a37d539f | 943 | For this to work, there are two services involved: |
c21d2cbe | 944 | |
a37d539f | 945 | * A QDevice daemon which runs on each {pve} node |
c21d2cbe | 946 | |
a37d539f | 947 | * An external vote daemon which runs on an independent server |
c21d2cbe | 948 | |
a37d539f | 949 | As a result, you can achieve higher availability, even in smaller setups (for |
c21d2cbe OB |
950 | example 2+1 nodes). |
951 | ||
952 | QDevice Technical Overview | |
953 | ~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
954 | ||
5f318cc0 | 955 | The Corosync Quorum Device (QDevice) is a daemon which runs on each cluster |
a37d539f DW |
956 | node. It provides a configured number of votes to the cluster's quorum |
957 | subsystem, based on an externally running third-party arbitrator's decision. | |
c21d2cbe OB |
958 | Its primary use is to allow a cluster to sustain more node failures than |
959 | standard quorum rules allow. This can be done safely as the external device | |
960 | can see all nodes and thus choose only one set of nodes to give its vote. | |
a37d539f | 961 | This will only be done if said set of nodes can have quorum (again) after |
c21d2cbe OB |
962 | receiving the third-party vote. |
963 | ||
a37d539f DW |
964 | Currently, only 'QDevice Net' is supported as a third-party arbitrator. This is |
965 | a daemon which provides a vote to a cluster partition, if it can reach the | |
966 | partition members over the network. It will only give votes to one partition | |
c21d2cbe OB |
967 | of a cluster at any time. |
968 | It's designed to support multiple clusters and is almost configuration and | |
969 | state free. New clusters are handled dynamically and no configuration file | |
970 | is needed on the host running a QDevice. | |
971 | ||
a37d539f DW |
972 | The only requirements for the external host are that it needs network access to |
973 | the cluster and to have a corosync-qnetd package available. We provide a package | |
974 | for Debian based hosts, and other Linux distributions should also have a package | |
c21d2cbe OB |
975 | available through their respective package manager. |
976 | ||
977 | NOTE: In contrast to corosync itself, a QDevice connects to the cluster over | |
a37d539f | 978 | TCP/IP. The daemon may even run outside of the cluster's LAN and can have longer |
a9e7c3aa | 979 | latencies than 2 ms. |
c21d2cbe OB |
980 | |
981 | Supported Setups | |
982 | ~~~~~~~~~~~~~~~~ | |
983 | ||
984 | We support QDevices for clusters with an even number of nodes and recommend | |
985 | it for 2 node clusters, if they should provide higher availability. | |
a37d539f DW |
986 | For clusters with an odd node count, we currently discourage the use of |
987 | QDevices. The reason for this is the difference in the votes which the QDevice | |
988 | provides for each cluster type. Even numbered clusters get a single additional | |
989 | vote, which only increases availability, because if the QDevice | |
990 | itself fails, you are in the same position as with no QDevice at all. | |
991 | ||
992 | On the other hand, with an odd numbered cluster size, the QDevice provides | |
993 | '(N-1)' votes -- where 'N' corresponds to the cluster node count. This | |
994 | alternative behavior makes sense; if it had only one additional vote, the | |
995 | cluster could get into a split-brain situation. This algorithm allows for all | |
996 | nodes but one (and naturally the QDevice itself) to fail. However, there are two | |
997 | drawbacks to this: | |
c21d2cbe OB |
998 | |
999 | * If the QNet daemon itself fails, no other node may fail or the cluster | |
a37d539f | 1000 | immediately loses quorum. For example, in a cluster with 15 nodes, 7 |
c21d2cbe | 1001 | could fail before the cluster becomes inquorate. But, if a QDevice is |
a37d539f DW |
1002 | configured here and it itself fails, **no single node** of the 15 may fail. |
1003 | The QDevice acts almost as a single point of failure in this case. | |
c21d2cbe | 1004 | |
a37d539f DW |
1005 | * The fact that all but one node plus QDevice may fail sounds promising at |
1006 | first, but this may result in a mass recovery of HA services, which could | |
1007 | overload the single remaining node. Furthermore, a Ceph server will stop | |
1008 | providing services if only '((N-1)/2)' nodes or less remain online. | |
c21d2cbe | 1009 | |
a37d539f DW |
1010 | If you understand the drawbacks and implications, you can decide yourself if |
1011 | you want to use this technology in an odd numbered cluster setup. | |
c21d2cbe | 1012 | |
c21d2cbe OB |
1013 | QDevice-Net Setup |
1014 | ~~~~~~~~~~~~~~~~~ | |
1015 | ||
a37d539f | 1016 | We recommend running any daemon which provides votes to corosync-qdevice as an |
7c039095 | 1017 | unprivileged user. {pve} and Debian provide a package which is already |
e34c3e91 | 1018 | configured to do so. |
c21d2cbe | 1019 | The traffic between the daemon and the cluster must be encrypted to ensure a |
a37d539f | 1020 | safe and secure integration of the QDevice in {pve}. |
c21d2cbe | 1021 | |
41a37193 DJ |
1022 | First, install the 'corosync-qnetd' package on your external server |
1023 | ||
1024 | ---- | |
1025 | external# apt install corosync-qnetd | |
1026 | ---- | |
1027 | ||
1028 | and the 'corosync-qdevice' package on all cluster nodes | |
1029 | ||
1030 | ---- | |
1031 | pve# apt install corosync-qdevice | |
1032 | ---- | |
c21d2cbe | 1033 | |
a37d539f | 1034 | After doing this, ensure that all the nodes in the cluster are online. |
c21d2cbe | 1035 | |
a37d539f | 1036 | You can now set up your QDevice by running the following command on one |
c21d2cbe OB |
1037 | of the {pve} nodes: |
1038 | ||
1039 | ---- | |
1040 | pve# pvecm qdevice setup <QDEVICE-IP> | |
1041 | ---- | |
1042 | ||
1b80fbaa DJ |
1043 | The SSH key from the cluster will be automatically copied to the QDevice. |
1044 | ||
1045 | NOTE: Make sure that the SSH configuration on your external server allows root | |
1046 | login via password, if you are asked for a password during this step. | |
c21d2cbe | 1047 | |
a37d539f DW |
1048 | After you enter the password and all the steps have successfully completed, you |
1049 | will see "Done". You can verify that the QDevice has been set up with: | |
c21d2cbe OB |
1050 | |
1051 | ---- | |
1052 | pve# pvecm status | |
1053 | ||
1054 | ... | |
1055 | ||
1056 | Votequorum information | |
1057 | ~~~~~~~~~~~~~~~~~~~~~ | |
1058 | Expected votes: 3 | |
1059 | Highest expected: 3 | |
1060 | Total votes: 3 | |
1061 | Quorum: 2 | |
1062 | Flags: Quorate Qdevice | |
1063 | ||
1064 | Membership information | |
1065 | ~~~~~~~~~~~~~~~~~~~~~~ | |
1066 | Nodeid Votes Qdevice Name | |
1067 | 0x00000001 1 A,V,NMW 192.168.22.180 (local) | |
1068 | 0x00000002 1 A,V,NMW 192.168.22.181 | |
1069 | 0x00000000 1 Qdevice | |
1070 | ||
1071 | ---- | |
1072 | ||
c21d2cbe | 1073 | |
c21d2cbe OB |
1074 | Frequently Asked Questions |
1075 | ~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
1076 | ||
1077 | Tie Breaking | |
1078 | ^^^^^^^^^^^^ | |
1079 | ||
00821894 | 1080 | In case of a tie, where two same-sized cluster partitions cannot see each other |
a37d539f DW |
1081 | but can see the QDevice, the QDevice chooses one of those partitions randomly |
1082 | and provides a vote to it. | |
c21d2cbe | 1083 | |
d31de328 TL |
1084 | Possible Negative Implications |
1085 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | |
1086 | ||
a37d539f DW |
1087 | For clusters with an even node count, there are no negative implications when |
1088 | using a QDevice. If it fails to work, it is the same as not having a QDevice | |
1089 | at all. | |
d31de328 | 1090 | |
870c2817 OB |
1091 | Adding/Deleting Nodes After QDevice Setup |
1092 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | |
d31de328 TL |
1093 | |
1094 | If you want to add a new node or remove an existing one from a cluster with a | |
00821894 TL |
1095 | QDevice setup, you need to remove the QDevice first. After that, you can add or |
1096 | remove nodes normally. Once you have a cluster with an even node count again, | |
a37d539f | 1097 | you can set up the QDevice again as described previously. |
870c2817 OB |
1098 | |
1099 | Removing the QDevice | |
1100 | ^^^^^^^^^^^^^^^^^^^^ | |
1101 | ||
00821894 | 1102 | If you used the official `pvecm` tool to add the QDevice, you can remove it |
a37d539f | 1103 | by running: |
870c2817 OB |
1104 | |
1105 | ---- | |
1106 | pve# pvecm qdevice remove | |
1107 | ---- | |
d31de328 | 1108 | |
51730d56 TL |
1109 | //Still TODO |
1110 | //^^^^^^^^^^ | |
a9e7c3aa | 1111 | //There is still stuff to add here |
c21d2cbe OB |
1112 | |
1113 | ||
e4ec4154 TL |
1114 | Corosync Configuration |
1115 | ---------------------- | |
1116 | ||
a9e7c3aa SR |
1117 | The `/etc/pve/corosync.conf` file plays a central role in a {pve} cluster. It |
1118 | controls the cluster membership and its network. | |
1119 | For further information about it, check the corosync.conf man page: | |
e4ec4154 | 1120 | [source,bash] |
4d19cb00 | 1121 | ---- |
e4ec4154 | 1122 | man corosync.conf |
4d19cb00 | 1123 | ---- |
e4ec4154 | 1124 | |
a37d539f | 1125 | For node membership, you should always use the `pvecm` tool provided by {pve}. |
e4ec4154 TL |
1126 | You may have to edit the configuration file manually for other changes. |
1127 | Here are a few best practice tips for doing this. | |
1128 | ||
3254bfdd | 1129 | [[pvecm_edit_corosync_conf]] |
e4ec4154 TL |
1130 | Edit corosync.conf |
1131 | ~~~~~~~~~~~~~~~~~~ | |
1132 | ||
a9e7c3aa SR |
1133 | Editing the corosync.conf file is not always very straightforward. There are |
1134 | two on each cluster node, one in `/etc/pve/corosync.conf` and the other in | |
e4ec4154 TL |
1135 | `/etc/corosync/corosync.conf`. Editing the one in our cluster file system will |
1136 | propagate the changes to the local one, but not vice versa. | |
1137 | ||
a37d539f DW |
1138 | The configuration will get updated automatically, as soon as the file changes. |
1139 | This means that changes which can be integrated in a running corosync will take | |
1140 | effect immediately. Thus, you should always make a copy and edit that instead, | |
1141 | to avoid triggering unintended changes when saving the file while editing. | |
e4ec4154 TL |
1142 | |
1143 | [source,bash] | |
4d19cb00 | 1144 | ---- |
e4ec4154 | 1145 | cp /etc/pve/corosync.conf /etc/pve/corosync.conf.new |
4d19cb00 | 1146 | ---- |
e4ec4154 | 1147 | |
a37d539f DW |
1148 | Then, open the config file with your favorite editor, such as `nano` or |
1149 | `vim.tiny`, which come pre-installed on every {pve} node. | |
e4ec4154 | 1150 | |
a37d539f | 1151 | NOTE: Always increment the 'config_version' number after configuration changes; |
e4ec4154 TL |
1152 | omitting this can lead to problems. |
1153 | ||
a37d539f | 1154 | After making the necessary changes, create another copy of the current working |
e4ec4154 | 1155 | configuration file. This serves as a backup if the new configuration fails to |
a37d539f | 1156 | apply or causes other issues. |
e4ec4154 TL |
1157 | |
1158 | [source,bash] | |
4d19cb00 | 1159 | ---- |
e4ec4154 | 1160 | cp /etc/pve/corosync.conf /etc/pve/corosync.conf.bak |
4d19cb00 | 1161 | ---- |
e4ec4154 | 1162 | |
a37d539f | 1163 | Then replace the old configuration file with the new one: |
e4ec4154 | 1164 | [source,bash] |
4d19cb00 | 1165 | ---- |
e4ec4154 | 1166 | mv /etc/pve/corosync.conf.new /etc/pve/corosync.conf |
4d19cb00 | 1167 | ---- |
e4ec4154 | 1168 | |
a37d539f DW |
1169 | You can check if the changes could be applied automatically, using the following |
1170 | commands: | |
e4ec4154 | 1171 | [source,bash] |
4d19cb00 | 1172 | ---- |
e4ec4154 TL |
1173 | systemctl status corosync |
1174 | journalctl -b -u corosync | |
4d19cb00 | 1175 | ---- |
e4ec4154 | 1176 | |
a37d539f | 1177 | If the changes could not be applied automatically, you may have to restart the |
e4ec4154 TL |
1178 | corosync service via: |
1179 | [source,bash] | |
4d19cb00 | 1180 | ---- |
e4ec4154 | 1181 | systemctl restart corosync |
4d19cb00 | 1182 | ---- |
e4ec4154 | 1183 | |
a37d539f | 1184 | On errors, check the troubleshooting section below. |
e4ec4154 TL |
1185 | |
1186 | Troubleshooting | |
1187 | ~~~~~~~~~~~~~~~ | |
1188 | ||
1189 | Issue: 'quorum.expected_votes must be configured' | |
1190 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | |
1191 | ||
1192 | When corosync starts to fail and you get the following message in the system log: | |
1193 | ||
1194 | ---- | |
1195 | [...] | |
1196 | corosync[1647]: [QUORUM] Quorum provider: corosync_votequorum failed to initialize. | |
1197 | corosync[1647]: [SERV ] Service engine 'corosync_quorum' failed to load for reason | |
1198 | 'configuration error: nodelist or quorum.expected_votes must be configured!' | |
1199 | [...] | |
1200 | ---- | |
1201 | ||
a37d539f | 1202 | It means that the hostname you set for a corosync 'ringX_addr' in the |
e4ec4154 TL |
1203 | configuration could not be resolved. |
1204 | ||
e4ec4154 TL |
1205 | Write Configuration When Not Quorate |
1206 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | |
1207 | ||
a37d539f DW |
1208 | If you need to change '/etc/pve/corosync.conf' on a node with no quorum, and you |
1209 | understand what you are doing, use: | |
e4ec4154 | 1210 | [source,bash] |
4d19cb00 | 1211 | ---- |
e4ec4154 | 1212 | pvecm expected 1 |
4d19cb00 | 1213 | ---- |
e4ec4154 TL |
1214 | |
1215 | This sets the expected vote count to 1 and makes the cluster quorate. You can | |
a37d539f | 1216 | then fix your configuration, or revert it back to the last working backup. |
e4ec4154 | 1217 | |
a37d539f DW |
1218 | This is not enough if corosync cannot start anymore. In that case, it is best to |
1219 | edit the local copy of the corosync configuration in | |
1220 | '/etc/corosync/corosync.conf', so that corosync can start again. Ensure that on | |
1221 | all nodes, this configuration has the same content to avoid split-brain | |
1222 | situations. | |
e4ec4154 TL |
1223 | |
1224 | ||
3254bfdd | 1225 | [[pvecm_corosync_conf_glossary]] |
e4ec4154 TL |
1226 | Corosync Configuration Glossary |
1227 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
1228 | ||
1229 | ringX_addr:: | |
a37d539f | 1230 | This names the different link addresses for the Kronosnet connections between |
a9e7c3aa | 1231 | nodes. |
e4ec4154 | 1232 | |
806ef12d DM |
1233 | |
1234 | Cluster Cold Start | |
1235 | ------------------ | |
1236 | ||
1237 | It is obvious that a cluster is not quorate when all nodes are | |
1238 | offline. This is a common case after a power failure. | |
1239 | ||
1240 | NOTE: It is always a good idea to use an uninterruptible power supply | |
8c1189b6 | 1241 | (``UPS'', also called ``battery backup'') to avoid this state, especially if |
806ef12d DM |
1242 | you want HA. |
1243 | ||
204231df | 1244 | On node startup, the `pve-guests` service is started and waits for |
8c1189b6 | 1245 | quorum. Once quorate, it starts all guests which have the `onboot` |
612417fd DM |
1246 | flag set. |
1247 | ||
1248 | When you turn on nodes, or when power comes back after power failure, | |
a37d539f | 1249 | it is likely that some nodes will boot faster than others. Please keep in |
612417fd | 1250 | mind that guest startup is delayed until you reach quorum. |
806ef12d | 1251 | |
054a7e7d | 1252 | |
082ea7d9 TL |
1253 | Guest Migration |
1254 | --------------- | |
1255 | ||
054a7e7d DM |
1256 | Migrating virtual guests to other nodes is a useful feature in a |
1257 | cluster. There are settings to control the behavior of such | |
1258 | migrations. This can be done via the configuration file | |
1259 | `datacenter.cfg` or for a specific migration via API or command line | |
1260 | parameters. | |
1261 | ||
a37d539f | 1262 | It makes a difference if a guest is online or offline, or if it has |
da6c7dee DC |
1263 | local resources (like a local disk). |
1264 | ||
a37d539f | 1265 | For details about virtual machine migration, see the |
a9e7c3aa | 1266 | xref:qm_migration[QEMU/KVM Migration Chapter]. |
da6c7dee | 1267 | |
a37d539f | 1268 | For details about container migration, see the |
a9e7c3aa | 1269 | xref:pct_migration[Container Migration Chapter]. |
082ea7d9 TL |
1270 | |
1271 | Migration Type | |
1272 | ~~~~~~~~~~~~~~ | |
1273 | ||
44f38275 | 1274 | The migration type defines if the migration data should be sent over an |
d63be10b | 1275 | encrypted (`secure`) channel or an unencrypted (`insecure`) one. |
082ea7d9 | 1276 | Setting the migration type to insecure means that the RAM content of a |
a37d539f | 1277 | virtual guest is also transferred unencrypted, which can lead to |
b1743473 | 1278 | information disclosure of critical data from inside the guest (for |
a37d539f | 1279 | example, passwords or encryption keys). |
054a7e7d DM |
1280 | |
1281 | Therefore, we strongly recommend using the secure channel if you do | |
1282 | not have full control over the network and can not guarantee that no | |
6d3c0b34 | 1283 | one is eavesdropping on it. |
082ea7d9 | 1284 | |
054a7e7d DM |
1285 | NOTE: Storage migration does not follow this setting. Currently, it |
1286 | always sends the storage content over a secure channel. | |
1287 | ||
1288 | Encryption requires a lot of computing power, so this setting is often | |
1289 | changed to "unsafe" to achieve better performance. The impact on | |
1290 | modern systems is lower because they implement AES encryption in | |
b1743473 | 1291 | hardware. The performance impact is particularly evident in fast |
a37d539f | 1292 | networks, where you can transfer 10 Gbps or more. |
082ea7d9 | 1293 | |
082ea7d9 TL |
1294 | Migration Network |
1295 | ~~~~~~~~~~~~~~~~~ | |
1296 | ||
a9baa444 | 1297 | By default, {pve} uses the network in which cluster communication |
a37d539f | 1298 | takes place to send the migration traffic. This is not optimal both because |
a9baa444 TL |
1299 | sensitive cluster traffic can be disrupted and this network may not |
1300 | have the best bandwidth available on the node. | |
1301 | ||
1302 | Setting the migration network parameter allows the use of a dedicated | |
a37d539f | 1303 | network for all migration traffic. In addition to the memory, |
a9baa444 TL |
1304 | this also affects the storage traffic for offline migrations. |
1305 | ||
a37d539f DW |
1306 | The migration network is set as a network using CIDR notation. This |
1307 | has the advantage that you don't have to set individual IP addresses | |
1308 | for each node. {pve} can determine the real address on the | |
1309 | destination node from the network specified in the CIDR form. To | |
1310 | enable this, the network must be specified so that each node has exactly one | |
1311 | IP in the respective network. | |
a9baa444 | 1312 | |
082ea7d9 TL |
1313 | Example |
1314 | ^^^^^^^ | |
1315 | ||
a37d539f | 1316 | We assume that we have a three-node setup, with three separate |
a9baa444 | 1317 | networks. One for public communication with the Internet, one for |
a37d539f | 1318 | cluster communication, and a very fast one, which we want to use as a |
a9baa444 TL |
1319 | dedicated network for migration. |
1320 | ||
1321 | A network configuration for such a setup might look as follows: | |
082ea7d9 TL |
1322 | |
1323 | ---- | |
7a0d4784 | 1324 | iface eno1 inet manual |
082ea7d9 TL |
1325 | |
1326 | # public network | |
1327 | auto vmbr0 | |
1328 | iface vmbr0 inet static | |
8673c878 | 1329 | address 192.X.Y.57/24 |
082ea7d9 | 1330 | gateway 192.X.Y.1 |
7a39aabd AL |
1331 | bridge-ports eno1 |
1332 | bridge-stp off | |
1333 | bridge-fd 0 | |
082ea7d9 TL |
1334 | |
1335 | # cluster network | |
7a0d4784 WL |
1336 | auto eno2 |
1337 | iface eno2 inet static | |
8673c878 | 1338 | address 10.1.1.1/24 |
082ea7d9 TL |
1339 | |
1340 | # fast network | |
7a0d4784 WL |
1341 | auto eno3 |
1342 | iface eno3 inet static | |
8673c878 | 1343 | address 10.1.2.1/24 |
082ea7d9 TL |
1344 | ---- |
1345 | ||
a9baa444 TL |
1346 | Here, we will use the network 10.1.2.0/24 as a migration network. For |
1347 | a single migration, you can do this using the `migration_network` | |
1348 | parameter of the command line tool: | |
1349 | ||
082ea7d9 | 1350 | ---- |
b1743473 | 1351 | # qm migrate 106 tre --online --migration_network 10.1.2.0/24 |
082ea7d9 TL |
1352 | ---- |
1353 | ||
a9baa444 TL |
1354 | To configure this as the default network for all migrations in the |
1355 | cluster, set the `migration` property of the `/etc/pve/datacenter.cfg` | |
1356 | file: | |
1357 | ||
082ea7d9 | 1358 | ---- |
a9baa444 | 1359 | # use dedicated migration network |
b1743473 | 1360 | migration: secure,network=10.1.2.0/24 |
082ea7d9 TL |
1361 | ---- |
1362 | ||
a9baa444 | 1363 | NOTE: The migration type must always be set when the migration network |
a37d539f | 1364 | is set in `/etc/pve/datacenter.cfg`. |
a9baa444 | 1365 | |
806ef12d | 1366 | |
d8742b0c DM |
1367 | ifdef::manvolnum[] |
1368 | include::pve-copyright.adoc[] | |
1369 | endif::manvolnum[] |