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pvecm: language and format fixup

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- Fix wording, spelling, grammar
- Fix capitalisation in some titles
- Replace usage of e.g. and i.e.

Signed-off-by: Dylan Whyte <d.whyte@proxmox.com>
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Dylan Whyte 2021-09-15 15:36:13 +02:00 committed by Thomas Lamprecht
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@ -33,19 +33,19 @@ network performance. Currently (2021), there are reports of clusters (using
high-end enterprise hardware) with over 50 nodes in production. high-end enterprise hardware) with over 50 nodes in production.
`pvecm` can be used to create a new cluster, join nodes to a cluster, `pvecm` can be used to create a new cluster, join nodes to a cluster,
leave the cluster, get status information and do various other cluster-related leave the cluster, get status information, and do various other cluster-related
tasks. The **P**rox**m**o**x** **C**luster **F**ile **S**ystem (``pmxcfs'') tasks. The **P**rox**m**o**x** **C**luster **F**ile **S**ystem (``pmxcfs'')
is used to transparently distribute the cluster configuration to all cluster is used to transparently distribute the cluster configuration to all cluster
nodes. nodes.
Grouping nodes into a cluster has the following advantages: Grouping nodes into a cluster has the following advantages:
* Centralized, web based management * Centralized, web-based management
* Multi-master clusters: each node can do all management tasks * Multi-master clusters: each node can do all management tasks
* `pmxcfs`: database-driven file system for storing configuration files, * Use of `pmxcfs`, a database-driven file system, for storing configuration
replicated in real-time on all nodes using `corosync`. files, replicated in real-time on all nodes using `corosync`
* Easy migration of virtual machines and containers between physical * Easy migration of virtual machines and containers between physical
hosts hosts
@ -61,9 +61,9 @@ Requirements
* All nodes must be able to connect to each other via UDP ports 5404 and 5405 * All nodes must be able to connect to each other via UDP ports 5404 and 5405
for corosync to work. for corosync to work.
* Date and time have to be synchronized. * Date and time must be synchronized.
* SSH tunnel on TCP port 22 between nodes is used. * An SSH tunnel on TCP port 22 between nodes is required.
* If you are interested in High Availability, you need to have at * If you are interested in High Availability, you need to have at
least three nodes for reliable quorum. All nodes should have the least three nodes for reliable quorum. All nodes should have the
@ -72,14 +72,14 @@ Requirements
* We recommend a dedicated NIC for the cluster traffic, especially if * We recommend a dedicated NIC for the cluster traffic, especially if
you use shared storage. you use shared storage.
* Root password of a cluster node is required for adding nodes. * The root password of a cluster node is required for adding nodes.
NOTE: It is not possible to mix {pve} 3.x and earlier with {pve} 4.X cluster NOTE: It is not possible to mix {pve} 3.x and earlier with {pve} 4.X cluster
nodes. nodes.
NOTE: While it's possible to mix {pve} 4.4 and {pve} 5.0 nodes, doing so is NOTE: While it's possible to mix {pve} 4.4 and {pve} 5.0 nodes, doing so is
not supported as production configuration and should only used temporarily not supported as a production configuration and should only be done temporarily,
during upgrading the whole cluster from one to another major version. during an upgrade of the whole cluster from one major version to another.
NOTE: Running a cluster of {pve} 6.x with earlier versions is not possible. The NOTE: Running a cluster of {pve} 6.x with earlier versions is not possible. The
cluster protocol (corosync) between {pve} 6.x and earlier versions changed cluster protocol (corosync) between {pve} 6.x and earlier versions changed
@ -94,12 +94,12 @@ First, install {PVE} on all nodes. Make sure that each node is
installed with the final hostname and IP configuration. Changing the installed with the final hostname and IP configuration. Changing the
hostname and IP is not possible after cluster creation. hostname and IP is not possible after cluster creation.
While it's common to reference all nodenames and their IPs in `/etc/hosts` (or While it's common to reference all node names and their IPs in `/etc/hosts` (or
make their names resolvable through other means), this is not necessary for a make their names resolvable through other means), this is not necessary for a
cluster to work. It may be useful however, as you can then connect from one node cluster to work. It may be useful however, as you can then connect from one node
to the other with SSH via the easier to remember node name (see also to another via SSH, using the easier to remember node name (see also
xref:pvecm_corosync_addresses[Link Address Types]). Note that we always xref:pvecm_corosync_addresses[Link Address Types]). Note that we always
recommend to reference nodes by their IP addresses in the cluster configuration. recommend referencing nodes by their IP addresses in the cluster configuration.
[[pvecm_create_cluster]] [[pvecm_create_cluster]]
@ -107,7 +107,7 @@ Create a Cluster
---------------- ----------------
You can either create a cluster on the console (login via `ssh`), or through You can either create a cluster on the console (login via `ssh`), or through
the API using the {pve} Webinterface (__Datacenter -> Cluster__). the API using the {pve} web interface (__Datacenter -> Cluster__).
NOTE: Use a unique name for your cluster. This name cannot be changed later. NOTE: Use a unique name for your cluster. This name cannot be changed later.
The cluster name follows the same rules as node names. The cluster name follows the same rules as node names.
@ -119,23 +119,23 @@ Create via Web GUI
[thumbnail="screenshot/gui-cluster-create.png"] [thumbnail="screenshot/gui-cluster-create.png"]
Under __Datacenter -> Cluster__, click on *Create Cluster*. Enter the cluster Under __Datacenter -> Cluster__, click on *Create Cluster*. Enter the cluster
name and select a network connection from the dropdown to serve as the main name and select a network connection from the drop-down list to serve as the
cluster network (Link 0). It defaults to the IP resolved via the node's main cluster network (Link 0). It defaults to the IP resolved via the node's
hostname. hostname.
To add a second link as fallback, you can select the 'Advanced' checkbox and To add a second link as fallback, you can select the 'Advanced' checkbox and
choose an additional network interface (Link 1, see also choose an additional network interface (Link 1, see also
xref:pvecm_redundancy[Corosync Redundancy]). xref:pvecm_redundancy[Corosync Redundancy]).
NOTE: Ensure the network selected for the cluster communication is not used for NOTE: Ensure that the network selected for cluster communication is not used for
any high traffic loads like those of (network) storages or live-migration. any high traffic purposes, like network storage or live-migration.
While the cluster network itself produces small amounts of data, it is very While the cluster network itself produces small amounts of data, it is very
sensitive to latency. Check out full sensitive to latency. Check out full
xref:pvecm_cluster_network_requirements[cluster network requirements]. xref:pvecm_cluster_network_requirements[cluster network requirements].
[[pvecm_cluster_create_via_cli]] [[pvecm_cluster_create_via_cli]]
Create via Command Line Create via the Command Line
~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~
Login via `ssh` to the first {pve} node and run the following command: Login via `ssh` to the first {pve} node and run the following command:
@ -149,13 +149,13 @@ To check the state of the new cluster use:
hp1# pvecm status hp1# pvecm status
---- ----
Multiple Clusters In Same Network Multiple Clusters in the Same Network
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
It is possible to create multiple clusters in the same physical or logical It is possible to create multiple clusters in the same physical or logical
network. Each such cluster must have a unique name to avoid possible clashes in network. In this case, each cluster must have a unique name to avoid possible
the cluster communication stack. This also helps avoid human confusion by making clashes in the cluster communication stack. Furthermore, this helps avoid human
clusters clearly distinguishable. confusion by making clusters clearly distinguishable.
While the bandwidth requirement of a corosync cluster is relatively low, the While the bandwidth requirement of a corosync cluster is relatively low, the
latency of packages and the package per second (PPS) rate is the limiting latency of packages and the package per second (PPS) rate is the limiting
@ -169,23 +169,23 @@ Adding Nodes to the Cluster
CAUTION: A node that is about to be added to the cluster cannot hold any guests. CAUTION: A node that is about to be added to the cluster cannot hold any guests.
All existing configuration in `/etc/pve` is overwritten when joining a cluster, All existing configuration in `/etc/pve` is overwritten when joining a cluster,
since guest IDs could be conflicting. As a workaround create a backup of the since guest IDs could otherwise conflict. As a workaround, you can create a
guest (`vzdump`) and restore it as a different ID after the node has been added backup of the guest (`vzdump`) and restore it under a different ID, after the
to the cluster. node has been added to the cluster.
Join Node to Cluster via GUI Join Node to Cluster via GUI
~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[thumbnail="screenshot/gui-cluster-join-information.png"] [thumbnail="screenshot/gui-cluster-join-information.png"]
Login to the web interface on an existing cluster node. Under __Datacenter -> Log in to the web interface on an existing cluster node. Under __Datacenter ->
Cluster__, click the button *Join Information* at the top. Then, click on the Cluster__, click the *Join Information* button at the top. Then, click on the
button *Copy Information*. Alternatively, copy the string from the 'Information' button *Copy Information*. Alternatively, copy the string from the 'Information'
field manually. field manually.
[thumbnail="screenshot/gui-cluster-join.png"] [thumbnail="screenshot/gui-cluster-join.png"]
Next, login to the web interface on the node you want to add. Next, log in to the web interface on the node you want to add.
Under __Datacenter -> Cluster__, click on *Join Cluster*. Fill in the Under __Datacenter -> Cluster__, click on *Join Cluster*. Fill in the
'Information' field with the 'Join Information' text you copied earlier. 'Information' field with the 'Join Information' text you copied earlier.
Most settings required for joining the cluster will be filled out Most settings required for joining the cluster will be filled out
@ -196,24 +196,24 @@ NOTE: To enter all required data manually, you can disable the 'Assisted Join'
checkbox. checkbox.
After clicking the *Join* button, the cluster join process will start After clicking the *Join* button, the cluster join process will start
immediately. After the node joined the cluster its current node certificate immediately. After the node has joined the cluster, its current node certificate
will be replaced by one signed from the cluster certificate authority (CA), will be replaced by one signed from the cluster certificate authority (CA).
that means the current session will stop to work after a few seconds. You might This means that the current session will stop working after a few seconds. You
then need to force-reload the webinterface and re-login with the cluster then might need to force-reload the web interface and log in again with the
credentials. cluster credentials.
Now your node should be visible under __Datacenter -> Cluster__. Now your node should be visible under __Datacenter -> Cluster__.
Join Node to Cluster via Command Line Join Node to Cluster via Command Line
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Login via `ssh` to the node you want to join into an existing cluster. Log in to the node you want to join into an existing cluster via `ssh`.
---- ----
hp2# pvecm add IP-ADDRESS-CLUSTER hp2# pvecm add IP-ADDRESS-CLUSTER
---- ----
For `IP-ADDRESS-CLUSTER` use the IP or hostname of an existing cluster node. For `IP-ADDRESS-CLUSTER`, use the IP or hostname of an existing cluster node.
An IP address is recommended (see xref:pvecm_corosync_addresses[Link Address Types]). An IP address is recommended (see xref:pvecm_corosync_addresses[Link Address Types]).
@ -252,7 +252,7 @@ Membership information
0x00000004 1 192.168.15.94 0x00000004 1 192.168.15.94
---- ----
If you only want the list of all nodes use: If you only want a list of all nodes, use:
---- ----
# pvecm nodes # pvecm nodes
@ -272,10 +272,10 @@ Membership information
---- ----
[[pvecm_adding_nodes_with_separated_cluster_network]] [[pvecm_adding_nodes_with_separated_cluster_network]]
Adding Nodes With Separated Cluster Network Adding Nodes with Separated Cluster Network
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When adding a node to a cluster with a separated cluster network you need to When adding a node to a cluster with a separated cluster network, you need to
use the 'link0' parameter to set the nodes address on that network: use the 'link0' parameter to set the nodes address on that network:
[source,bash] [source,bash]
@ -284,20 +284,20 @@ pvecm add IP-ADDRESS-CLUSTER -link0 LOCAL-IP-ADDRESS-LINK0
---- ----
If you want to use the built-in xref:pvecm_redundancy[redundancy] of the If you want to use the built-in xref:pvecm_redundancy[redundancy] of the
kronosnet transport layer, also use the 'link1' parameter. Kronosnet transport layer, also use the 'link1' parameter.
Using the GUI, you can select the correct interface from the corresponding 'Link 0' Using the GUI, you can select the correct interface from the corresponding
and 'Link 1' fields in the *Cluster Join* dialog. 'Link X' fields in the *Cluster Join* dialog.
Remove a Cluster Node Remove a Cluster Node
--------------------- ---------------------
CAUTION: Read carefully the procedure before proceeding, as it could CAUTION: Read the procedure carefully before proceeding, as it may
not be what you want or need. not be what you want or need.
Move all virtual machines from the node. Make sure you have no local Move all virtual machines from the node. Make sure you have made copies of any
data or backups you want to keep, or save them accordingly. local data or backups that you want to keep. In the following example, we will
In the following example we will remove the node hp4 from the cluster. remove the node hp4 from the cluster.
Log in to a *different* cluster node (not hp4), and issue a `pvecm nodes` Log in to a *different* cluster node (not hp4), and issue a `pvecm nodes`
command to identify the node ID to remove: command to identify the node ID to remove:
@ -315,15 +315,14 @@ Membership information
---- ----
At this point you must power off hp4 and At this point, you must power off hp4 and ensure that it will not power on
make sure that it will not power on again (in the network) as it again (in the network) with its current configuration.
is.
IMPORTANT: As said above, it is critical to power off the node IMPORTANT: As mentioned above, it is critical to power off the node
*before* removal, and make sure that it will *never* power on again *before* removal, and make sure that it will *not* power on again
(in the existing cluster network) as it is. (in the existing cluster network) with its current configuration.
If you power on the node as it is, your cluster will be screwed up and If you power on the node as it is, the cluster could end up broken,
it could be difficult to restore a clean cluster state. and it could be difficult to restore it to a functioning state.
After powering off the node hp4, we can safely remove it from the cluster. After powering off the node hp4, we can safely remove it from the cluster.
@ -364,9 +363,9 @@ Membership information
---- ----
If, for whatever reason, you want this server to join the same cluster again, If, for whatever reason, you want this server to join the same cluster again,
you have to you have to:
* reinstall {pve} on it from scratch * do a fresh install of {pve} on it,
* then join it, as explained in the previous section. * then join it, as explained in the previous section.
@ -376,37 +375,37 @@ a node with the same IP or hostname, run `pvecm updatecerts` once on the
re-added node to update its fingerprint cluster wide. re-added node to update its fingerprint cluster wide.
[[pvecm_separate_node_without_reinstall]] [[pvecm_separate_node_without_reinstall]]
Separate A Node Without Reinstalling Separate a Node Without Reinstalling
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CAUTION: This is *not* the recommended method, proceed with caution. Use the CAUTION: This is *not* the recommended method, proceed with caution. Use the
above mentioned method if you're unsure. previous method if you're unsure.
You can also separate a node from a cluster without reinstalling it from You can also separate a node from a cluster without reinstalling it from
scratch. But after removing the node from the cluster it will still have scratch. But after removing the node from the cluster, it will still have
access to the shared storages! This must be resolved before you start removing access to any shared storage. This must be resolved before you start removing
the node from the cluster. A {pve} cluster cannot share the exact same the node from the cluster. A {pve} cluster cannot share the exact same
storage with another cluster, as storage locking doesn't work over the cluster storage with another cluster, as storage locking doesn't work over the cluster
boundary. Further, it may also lead to VMID conflicts. boundary. Furthermore, it may also lead to VMID conflicts.
Its suggested that you create a new storage where only the node which you want It's suggested that you create a new storage, where only the node which you want
to separate has access. This can be a new export on your NFS or a new Ceph to separate has access. This can be a new export on your NFS or a new Ceph
pool, to name a few examples. Its just important that the exact same storage pool, to name a few examples. It's just important that the exact same storage
does not gets accessed by multiple clusters. After setting this storage up move does not get accessed by multiple clusters. After setting up this storage, move
all data from the node and its VMs to it. Then you are ready to separate the all data and VMs from the node to it. Then you are ready to separate the
node from the cluster. node from the cluster.
WARNING: Ensure all shared resources are cleanly separated! Otherwise you will WARNING: Ensure that all shared resources are cleanly separated! Otherwise you
run into conflicts and problems. will run into conflicts and problems.
First, stop the corosync and the pve-cluster services on the node: First, stop the corosync and pve-cluster services on the node:
[source,bash] [source,bash]
---- ----
systemctl stop pve-cluster systemctl stop pve-cluster
systemctl stop corosync systemctl stop corosync
---- ----
Start the cluster filesystem again in local mode: Start the cluster file system again in local mode:
[source,bash] [source,bash]
---- ----
pmxcfs -l pmxcfs -l
@ -419,22 +418,22 @@ rm /etc/pve/corosync.conf
rm -r /etc/corosync/* rm -r /etc/corosync/*
---- ----
You can now start the filesystem again as normal service: You can now start the file system again as a normal service:
[source,bash] [source,bash]
---- ----
killall pmxcfs killall pmxcfs
systemctl start pve-cluster systemctl start pve-cluster
---- ----
The node is now separated from the cluster. You can deleted it from a remaining The node is now separated from the cluster. You can deleted it from any
node of the cluster with: remaining node of the cluster with:
[source,bash] [source,bash]
---- ----
pvecm delnode oldnode pvecm delnode oldnode
---- ----
If the command failed, because the remaining node in the cluster lost quorum If the command fails due to a loss of quorum in the remaining node, you can set
when the now separate node exited, you may set the expected votes to 1 as a workaround: the expected votes to 1 as a workaround:
[source,bash] [source,bash]
---- ----
pvecm expected 1 pvecm expected 1
@ -442,9 +441,9 @@ pvecm expected 1
And then repeat the 'pvecm delnode' command. And then repeat the 'pvecm delnode' command.
Now switch back to the separated node, here delete all remaining files left Now switch back to the separated node and delete all the remaining cluster
from the old cluster. This ensures that the node can be added to another files on it. This ensures that the node can be added to another cluster again
cluster again without problems. without problems.
[source,bash] [source,bash]
---- ----
@ -452,13 +451,13 @@ rm /var/lib/corosync/*
---- ----
As the configuration files from the other nodes are still in the cluster As the configuration files from the other nodes are still in the cluster
filesystem you may want to clean those up too. Remove simply the whole file system, you may want to clean those up too. After making absolutely sure
directory recursive from '/etc/pve/nodes/NODENAME', but check three times that that you have the correct node name, you can simply remove the entire
you used the correct one before deleting it. directory recursively from '/etc/pve/nodes/NODENAME'.
CAUTION: The nodes SSH keys are still in the 'authorized_key' file, this means CAUTION: The node's SSH keys will remain in the 'authorized_key' file. This
the nodes can still connect to each other with public key authentication. This means that the nodes can still connect to each other with public key
should be fixed by removing the respective keys from the authentication. You should fix this by removing the respective keys from the
'/etc/pve/priv/authorized_keys' file. '/etc/pve/priv/authorized_keys' file.
@ -487,21 +486,21 @@ Cluster Network
The cluster network is the core of a cluster. All messages sent over it have to The cluster network is the core of a cluster. All messages sent over it have to
be delivered reliably to all nodes in their respective order. In {pve} this be delivered reliably to all nodes in their respective order. In {pve} this
part is done by corosync, an implementation of a high performance, low overhead part is done by corosync, an implementation of a high performance, low overhead,
high availability development toolkit. It serves our decentralized high availability development toolkit. It serves our decentralized configuration
configuration file system (`pmxcfs`). file system (`pmxcfs`).
[[pvecm_cluster_network_requirements]] [[pvecm_cluster_network_requirements]]
Network Requirements Network Requirements
~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~
This needs a reliable network with latencies under 2 milliseconds (LAN This needs a reliable network with latencies under 2 milliseconds (LAN
performance) to work properly. The network should not be used heavily by other performance) to work properly. The network should not be used heavily by other
members, ideally corosync runs on its own network. Do not use a shared network members; ideally corosync runs on its own network. Do not use a shared network
for corosync and storage (except as a potential low-priority fallback in a for corosync and storage (except as a potential low-priority fallback in a
xref:pvecm_redundancy[redundant] configuration). xref:pvecm_redundancy[redundant] configuration).
Before setting up a cluster, it is good practice to check if the network is fit Before setting up a cluster, it is good practice to check if the network is fit
for that purpose. To make sure the nodes can connect to each other on the for that purpose. To ensure that the nodes can connect to each other on the
cluster network, you can test the connectivity between them with the `ping` cluster network, you can test the connectivity between them with the `ping`
tool. tool.
@ -520,13 +519,13 @@ This is therefore not recommended.
Separate Cluster Network Separate Cluster Network
~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~
When creating a cluster without any parameters the corosync cluster network is When creating a cluster without any parameters, the corosync cluster network is
generally shared with the Web UI and the VMs and their traffic. Depending on generally shared with the web interface and the VMs' network. Depending on
your setup, even storage traffic may get sent over the same network. Its your setup, even storage traffic may get sent over the same network. It's
recommended to change that, as corosync is a time critical real time recommended to change that, as corosync is a time-critical, real-time
application. application.
Setting Up A New Network Setting Up a New Network
^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^
First, you have to set up a new network interface. It should be on a physically First, you have to set up a new network interface. It should be on a physically
@ -537,7 +536,7 @@ Separate On Cluster Creation
^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This is possible via the 'linkX' parameters of the 'pvecm create' This is possible via the 'linkX' parameters of the 'pvecm create'
command used for creating a new cluster. command, used for creating a new cluster.
If you have set up an additional NIC with a static address on 10.10.10.1/25, If you have set up an additional NIC with a static address on 10.10.10.1/25,
and want to send and receive all cluster communication over this interface, and want to send and receive all cluster communication over this interface,
@ -548,7 +547,7 @@ you would execute:
pvecm create test --link0 10.10.10.1 pvecm create test --link0 10.10.10.1
---- ----
To check if everything is working properly execute: To check if everything is working properly, execute:
[source,bash] [source,bash]
---- ----
systemctl status corosync systemctl status corosync
@ -563,7 +562,7 @@ Separate After Cluster Creation
You can do this if you have already created a cluster and want to switch You can do this if you have already created a cluster and want to switch
its communication to another network, without rebuilding the whole cluster. its communication to another network, without rebuilding the whole cluster.
This change may lead to short durations of quorum loss in the cluster, as nodes This change may lead to short periods of quorum loss in the cluster, as nodes
have to restart corosync and come up one after the other on the new network. have to restart corosync and come up one after the other on the new network.
Check how to xref:pvecm_edit_corosync_conf[edit the corosync.conf file] first. Check how to xref:pvecm_edit_corosync_conf[edit the corosync.conf file] first.
@ -617,24 +616,24 @@ totem {
} }
---- ----
NOTE: `ringX_addr` actually specifies a corosync *link address*, the name "ring" NOTE: `ringX_addr` actually specifies a corosync *link address*. The name "ring"
is a remnant of older corosync versions that is kept for backwards is a remnant of older corosync versions that is kept for backwards
compatibility. compatibility.
The first thing you want to do is add the 'name' properties in the node entries The first thing you want to do is add the 'name' properties in the node entries,
if you do not see them already. Those *must* match the node name. if you do not see them already. Those *must* match the node name.
Then replace all addresses from the 'ring0_addr' properties of all nodes with Then replace all addresses from the 'ring0_addr' properties of all nodes with
the new addresses. You may use plain IP addresses or hostnames here. If you use the new addresses. You may use plain IP addresses or hostnames here. If you use
hostnames ensure that they are resolvable from all nodes. (see also hostnames, ensure that they are resolvable from all nodes (see also
xref:pvecm_corosync_addresses[Link Address Types]) xref:pvecm_corosync_addresses[Link Address Types]).
In this example, we want to switch the cluster communication to the In this example, we want to switch cluster communication to the
10.10.10.1/25 network. So we replace all 'ring0_addr' respectively. 10.10.10.1/25 network, so we change the 'ring0_addr' of each node respectively.
NOTE: The exact same procedure can be used to change other 'ringX_addr' values NOTE: The exact same procedure can be used to change other 'ringX_addr' values
as well, although we recommend to not change multiple addresses at once, to make as well. However, we recommend only changing one link address at a time, so
it easier to recover if something goes wrong. that it's easier to recover if something goes wrong.
After we increase the 'config_version' property, the new configuration file After we increase the 'config_version' property, the new configuration file
should look like: should look like:
@ -687,9 +686,10 @@ totem {
} }
---- ----
Then, after a final check if all changed information is correct, we save it and Then, after a final check to see that all changed information is correct, we
once again follow the xref:pvecm_edit_corosync_conf[edit corosync.conf file] save it and once again follow the
section to bring it into effect. xref:pvecm_edit_corosync_conf[edit corosync.conf file] section to bring it into
effect.
The changes will be applied live, so restarting corosync is not strictly The changes will be applied live, so restarting corosync is not strictly
necessary. If you changed other settings as well, or notice corosync necessary. If you changed other settings as well, or notice corosync
@ -702,32 +702,32 @@ On a single node execute:
systemctl restart corosync systemctl restart corosync
---- ----
Now check if everything is fine: Now check if everything is okay:
[source,bash] [source,bash]
---- ----
systemctl status corosync systemctl status corosync
---- ----
If corosync runs again correct restart corosync also on all other nodes. If corosync begins to work again, restart it on all other nodes too.
They will then join the cluster membership one by one on the new network. They will then join the cluster membership one by one on the new network.
[[pvecm_corosync_addresses]] [[pvecm_corosync_addresses]]
Corosync addresses Corosync Addresses
~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~
A corosync link address (for backwards compatibility denoted by 'ringX_addr' in A corosync link address (for backwards compatibility denoted by 'ringX_addr' in
`corosync.conf`) can be specified in two ways: `corosync.conf`) can be specified in two ways:
* **IPv4/v6 addresses** will be used directly. They are recommended, since they * **IPv4/v6 addresses** can be used directly. They are recommended, since they
are static and usually not changed carelessly. are static and usually not changed carelessly.
* **Hostnames** will be resolved using `getaddrinfo`, which means that per * **Hostnames** will be resolved using `getaddrinfo`, which means that by
default, IPv6 addresses will be used first, if available (see also default, IPv6 addresses will be used first, if available (see also
`man gai.conf`). Keep this in mind, especially when upgrading an existing `man gai.conf`). Keep this in mind, especially when upgrading an existing
cluster to IPv6. cluster to IPv6.
CAUTION: Hostnames should be used with care, since the address they CAUTION: Hostnames should be used with care, since the addresses they
resolve to can be changed without touching corosync or the node it runs on - resolve to can be changed without touching corosync or the node it runs on -
which may lead to a situation where an address is changed without thinking which may lead to a situation where an address is changed without thinking
about implications for corosync. about implications for corosync.
@ -737,7 +737,7 @@ hostnames are preferred. Also, make sure that every node in the cluster can
resolve all hostnames correctly. resolve all hostnames correctly.
Since {pve} 5.1, while supported, hostnames will be resolved at the time of Since {pve} 5.1, while supported, hostnames will be resolved at the time of
entry. Only the resolved IP is then saved to the configuration. entry. Only the resolved IP is saved to the configuration.
Nodes that joined the cluster on earlier versions likely still use their Nodes that joined the cluster on earlier versions likely still use their
unresolved hostname in `corosync.conf`. It might be a good idea to replace unresolved hostname in `corosync.conf`. It might be a good idea to replace
@ -748,7 +748,7 @@ them with IPs or a separate hostname, as mentioned above.
Corosync Redundancy Corosync Redundancy
------------------- -------------------
Corosync supports redundant networking via its integrated kronosnet layer by Corosync supports redundant networking via its integrated Kronosnet layer by
default (it is not supported on the legacy udp/udpu transports). It can be default (it is not supported on the legacy udp/udpu transports). It can be
enabled by specifying more than one link address, either via the '--linkX' enabled by specifying more than one link address, either via the '--linkX'
parameters of `pvecm`, in the GUI as **Link 1** (while creating a cluster or parameters of `pvecm`, in the GUI as **Link 1** (while creating a cluster or
@ -774,13 +774,13 @@ links will be used in order of their number, with the lower number having higher
priority. priority.
Even if all links are working, only the one with the highest priority will see Even if all links are working, only the one with the highest priority will see
corosync traffic. Link priorities cannot be mixed, i.e. links with different corosync traffic. Link priorities cannot be mixed, meaning that links with
priorities will not be able to communicate with each other. different priorities will not be able to communicate with each other.
Since lower priority links will not see traffic unless all higher priorities Since lower priority links will not see traffic unless all higher priorities
have failed, it becomes a useful strategy to specify even networks used for have failed, it becomes a useful strategy to specify networks used for
other tasks (VMs, storage, etc...) as low-priority links. If worst comes to other tasks (VMs, storage, etc.) as low-priority links. If worst comes to
worst, a higher-latency or more congested connection might be better than no worst, a higher latency or more congested connection might be better than no
connection at all. connection at all.
Adding Redundant Links To An Existing Cluster Adding Redundant Links To An Existing Cluster
@ -794,7 +794,7 @@ sure that your 'X' is the same for every node you add it to, and that it is
unique for each node. unique for each node.
Lastly, add a new 'interface', as shown below, to your `totem` Lastly, add a new 'interface', as shown below, to your `totem`
section, replacing 'X' with your link number chosen above. section, replacing 'X' with the link number chosen above.
Assuming you added a link with number 1, the new configuration file could look Assuming you added a link with number 1, the new configuration file could look
like this: like this:
@ -884,7 +884,7 @@ B via a non-interactive SSH tunnel.
* VM and CT memory and local-storage migration in 'secure' mode. * VM and CT memory and local-storage migration in 'secure' mode.
+ +
During the migration one or more SSH tunnel(s) are established between the During the migration, one or more SSH tunnel(s) are established between the
source and target nodes, in order to exchange migration information and source and target nodes, in order to exchange migration information and
transfer memory and disk contents. transfer memory and disk contents.
@ -896,8 +896,8 @@ transfer memory and disk contents.
In case you have a custom `.bashrc`, or similar files that get executed on In case you have a custom `.bashrc`, or similar files that get executed on
login by the configured shell, `ssh` will automatically run it once the session login by the configured shell, `ssh` will automatically run it once the session
is established successfully. This can cause some unexpected behavior, as those is established successfully. This can cause some unexpected behavior, as those
commands may be executed with root permissions on any above described commands may be executed with root permissions on any of the operations
operation. That can cause possible problematic side-effects! described above. This can cause possible problematic side-effects!
In order to avoid such complications, it's recommended to add a check in In order to avoid such complications, it's recommended to add a check in
`/root/.bashrc` to make sure the session is interactive, and only then run `/root/.bashrc` to make sure the session is interactive, and only then run
@ -922,42 +922,42 @@ This section describes a way to deploy an external voter in a {pve} cluster.
When configured, the cluster can sustain more node failures without When configured, the cluster can sustain more node failures without
violating safety properties of the cluster communication. violating safety properties of the cluster communication.
For this to work there are two services involved: For this to work, there are two services involved:
* a so called qdevice daemon which runs on each {pve} node * A QDevice daemon which runs on each {pve} node
* an external vote daemon which runs on an independent server. * An external vote daemon which runs on an independent server
As a result you can achieve higher availability even in smaller setups (for As a result, you can achieve higher availability, even in smaller setups (for
example 2+1 nodes). example 2+1 nodes).
QDevice Technical Overview QDevice Technical Overview
~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~
The Corosync Quorum Device (QDevice) is a daemon which runs on each cluster The Corosync Quorum Device (QDevice) is a daemon which runs on each cluster
node. It provides a configured number of votes to the clusters quorum node. It provides a configured number of votes to the cluster's quorum
subsystem based on an external running third-party arbitrator's decision. subsystem, based on an externally running third-party arbitrator's decision.
Its primary use is to allow a cluster to sustain more node failures than Its primary use is to allow a cluster to sustain more node failures than
standard quorum rules allow. This can be done safely as the external device standard quorum rules allow. This can be done safely as the external device
can see all nodes and thus choose only one set of nodes to give its vote. can see all nodes and thus choose only one set of nodes to give its vote.
This will only be done if said set of nodes can have quorum (again) when This will only be done if said set of nodes can have quorum (again) after
receiving the third-party vote. receiving the third-party vote.
Currently only 'QDevice Net' is supported as a third-party arbitrator. It is Currently, only 'QDevice Net' is supported as a third-party arbitrator. This is
a daemon which provides a vote to a cluster partition if it can reach the a daemon which provides a vote to a cluster partition, if it can reach the
partition members over the network. It will give only votes to one partition partition members over the network. It will only give votes to one partition
of a cluster at any time. of a cluster at any time.
It's designed to support multiple clusters and is almost configuration and It's designed to support multiple clusters and is almost configuration and
state free. New clusters are handled dynamically and no configuration file state free. New clusters are handled dynamically and no configuration file
is needed on the host running a QDevice. is needed on the host running a QDevice.
The external host has the only requirement that it needs network access to the The only requirements for the external host are that it needs network access to
cluster and a corosync-qnetd package available. We provide such a package the cluster and to have a corosync-qnetd package available. We provide a package
for Debian based hosts, other Linux distributions should also have a package for Debian based hosts, and other Linux distributions should also have a package
available through their respective package manager. available through their respective package manager.
NOTE: In contrast to corosync itself, a QDevice connects to the cluster over NOTE: In contrast to corosync itself, a QDevice connects to the cluster over
TCP/IP. The daemon may even run outside of the clusters LAN and can have longer TCP/IP. The daemon may even run outside of the cluster's LAN and can have longer
latencies than 2 ms. latencies than 2 ms.
Supported Setups Supported Setups
@ -965,43 +965,41 @@ Supported Setups
We support QDevices for clusters with an even number of nodes and recommend We support QDevices for clusters with an even number of nodes and recommend
it for 2 node clusters, if they should provide higher availability. it for 2 node clusters, if they should provide higher availability.
For clusters with an odd node count we discourage the use of QDevices For clusters with an odd node count, we currently discourage the use of
currently. The reason for this, is the difference of the votes the QDevice QDevices. The reason for this is the difference in the votes which the QDevice
provides for each cluster type. Even numbered clusters get single additional provides for each cluster type. Even numbered clusters get a single additional
vote, with this we can only increase availability, i.e. if the QDevice vote, which only increases availability, because if the QDevice
itself fails we are in the same situation as with no QDevice at all. itself fails, you are in the same position as with no QDevice at all.
Now, with an odd numbered cluster size the QDevice provides '(N-1)' votes -- On the other hand, with an odd numbered cluster size, the QDevice provides
where 'N' corresponds to the cluster node count. This difference makes '(N-1)' votes -- where 'N' corresponds to the cluster node count. This
sense, if we had only one additional vote the cluster can get into a split alternative behavior makes sense; if it had only one additional vote, the
brain situation. cluster could get into a split-brain situation. This algorithm allows for all
This algorithm would allow that all nodes but one (and naturally the nodes but one (and naturally the QDevice itself) to fail. However, there are two
QDevice itself) could fail. drawbacks to this:
There are two drawbacks with this:
* If the QNet daemon itself fails, no other node may fail or the cluster * If the QNet daemon itself fails, no other node may fail or the cluster
immediately loses quorum. For example, in a cluster with 15 nodes 7 immediately loses quorum. For example, in a cluster with 15 nodes, 7
could fail before the cluster becomes inquorate. But, if a QDevice is could fail before the cluster becomes inquorate. But, if a QDevice is
configured here and said QDevice fails itself **no single node** of configured here and it itself fails, **no single node** of the 15 may fail.
the 15 may fail. The QDevice acts almost as a single point of failure in The QDevice acts almost as a single point of failure in this case.
this case.
* The fact that all but one node plus QDevice may fail sound promising at * The fact that all but one node plus QDevice may fail sounds promising at
first, but this may result in a mass recovery of HA services that would first, but this may result in a mass recovery of HA services, which could
overload the single node left. Also ceph server will stop to provide overload the single remaining node. Furthermore, a Ceph server will stop
services after only '((N-1)/2)' nodes are online. providing services if only '((N-1)/2)' nodes or less remain online.
If you understand the drawbacks and implications you can decide yourself if If you understand the drawbacks and implications, you can decide yourself if
you should use this technology in an odd numbered cluster setup. you want to use this technology in an odd numbered cluster setup.
QDevice-Net Setup QDevice-Net Setup
~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~
We recommend to run any daemon which provides votes to corosync-qdevice as an We recommend running any daemon which provides votes to corosync-qdevice as an
unprivileged user. {pve} and Debian provide a package which is already unprivileged user. {pve} and Debian provide a package which is already
configured to do so. configured to do so.
The traffic between the daemon and the cluster must be encrypted to ensure a The traffic between the daemon and the cluster must be encrypted to ensure a
safe and secure QDevice integration in {pve}. safe and secure integration of the QDevice in {pve}.
First, install the 'corosync-qnetd' package on your external server First, install the 'corosync-qnetd' package on your external server
@ -1015,9 +1013,9 @@ and the 'corosync-qdevice' package on all cluster nodes
pve# apt install corosync-qdevice pve# apt install corosync-qdevice
---- ----
After that, ensure that all your nodes on the cluster are online. After doing this, ensure that all the nodes in the cluster are online.
You can now easily set up your QDevice by running the following command on one You can now set up your QDevice by running the following command on one
of the {pve} nodes: of the {pve} nodes:
---- ----
@ -1029,8 +1027,8 @@ The SSH key from the cluster will be automatically copied to the QDevice.
NOTE: Make sure that the SSH configuration on your external server allows root NOTE: Make sure that the SSH configuration on your external server allows root
login via password, if you are asked for a password during this step. login via password, if you are asked for a password during this step.
After you enter the password and all the steps are successfully completed, you After you enter the password and all the steps have successfully completed, you
will see "Done". You can check the status now: will see "Done". You can verify that the QDevice has been set up with:
---- ----
pve# pvecm status pve# pvecm status
@ -1054,7 +1052,6 @@ Membership information
---- ----
which means the QDevice is set up.
Frequently Asked Questions Frequently Asked Questions
~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~
@ -1063,15 +1060,15 @@ Tie Breaking
^^^^^^^^^^^^ ^^^^^^^^^^^^
In case of a tie, where two same-sized cluster partitions cannot see each other In case of a tie, where two same-sized cluster partitions cannot see each other
but the QDevice, the QDevice chooses randomly one of those partitions and but can see the QDevice, the QDevice chooses one of those partitions randomly
provides a vote to it. and provides a vote to it.
Possible Negative Implications Possible Negative Implications
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
For clusters with an even node count there are no negative implications when For clusters with an even node count, there are no negative implications when
setting up a QDevice. If it fails to work, you are as good as without QDevice at using a QDevice. If it fails to work, it is the same as not having a QDevice
all. at all.
Adding/Deleting Nodes After QDevice Setup Adding/Deleting Nodes After QDevice Setup
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -1079,13 +1076,13 @@ Adding/Deleting Nodes After QDevice Setup
If you want to add a new node or remove an existing one from a cluster with a If you want to add a new node or remove an existing one from a cluster with a
QDevice setup, you need to remove the QDevice first. After that, you can add or QDevice setup, you need to remove the QDevice first. After that, you can add or
remove nodes normally. Once you have a cluster with an even node count again, remove nodes normally. Once you have a cluster with an even node count again,
you can set up the QDevice again as described above. you can set up the QDevice again as described previously.
Removing the QDevice Removing the QDevice
^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^
If you used the official `pvecm` tool to add the QDevice, you can remove it If you used the official `pvecm` tool to add the QDevice, you can remove it
trivially by running: by running:
---- ----
pve# pvecm qdevice remove pve# pvecm qdevice remove
@ -1107,7 +1104,7 @@ For further information about it, check the corosync.conf man page:
man corosync.conf man corosync.conf
---- ----
For node membership you should always use the `pvecm` tool provided by {pve}. For node membership, you should always use the `pvecm` tool provided by {pve}.
You may have to edit the configuration file manually for other changes. You may have to edit the configuration file manually for other changes.
Here are a few best practice tips for doing this. Here are a few best practice tips for doing this.
@ -1120,52 +1117,53 @@ two on each cluster node, one in `/etc/pve/corosync.conf` and the other in
`/etc/corosync/corosync.conf`. Editing the one in our cluster file system will `/etc/corosync/corosync.conf`. Editing the one in our cluster file system will
propagate the changes to the local one, but not vice versa. propagate the changes to the local one, but not vice versa.
The configuration will get updated automatically as soon as the file changes. The configuration will get updated automatically, as soon as the file changes.
This means changes which can be integrated in a running corosync will take This means that changes which can be integrated in a running corosync will take
effect immediately. So you should always make a copy and edit that instead, to effect immediately. Thus, you should always make a copy and edit that instead,
avoid triggering some unwanted changes by an in-between safe. to avoid triggering unintended changes when saving the file while editing.
[source,bash] [source,bash]
---- ----
cp /etc/pve/corosync.conf /etc/pve/corosync.conf.new cp /etc/pve/corosync.conf /etc/pve/corosync.conf.new
---- ----
Then open the config file with your favorite editor, `nano` and `vim.tiny` are Then, open the config file with your favorite editor, such as `nano` or
preinstalled on any {pve} node for example. `vim.tiny`, which come pre-installed on every {pve} node.
NOTE: Always increment the 'config_version' number on configuration changes, NOTE: Always increment the 'config_version' number after configuration changes;
omitting this can lead to problems. omitting this can lead to problems.
After making the necessary changes create another copy of the current working After making the necessary changes, create another copy of the current working
configuration file. This serves as a backup if the new configuration fails to configuration file. This serves as a backup if the new configuration fails to
apply or makes problems in other ways. apply or causes other issues.
[source,bash] [source,bash]
---- ----
cp /etc/pve/corosync.conf /etc/pve/corosync.conf.bak cp /etc/pve/corosync.conf /etc/pve/corosync.conf.bak
---- ----
Then move the new configuration file over the old one: Then replace the old configuration file with the new one:
[source,bash] [source,bash]
---- ----
mv /etc/pve/corosync.conf.new /etc/pve/corosync.conf mv /etc/pve/corosync.conf.new /etc/pve/corosync.conf
---- ----
You may check with the commands You can check if the changes could be applied automatically, using the following
commands:
[source,bash] [source,bash]
---- ----
systemctl status corosync systemctl status corosync
journalctl -b -u corosync journalctl -b -u corosync
---- ----
If the change could be applied automatically. If not you may have to restart the If the changes could not be applied automatically, you may have to restart the
corosync service via: corosync service via:
[source,bash] [source,bash]
---- ----
systemctl restart corosync systemctl restart corosync
---- ----
On errors check the troubleshooting section below. On errors, check the troubleshooting section below.
Troubleshooting Troubleshooting
~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~
@ -1183,27 +1181,27 @@ corosync[1647]: [SERV ] Service engine 'corosync_quorum' failed to load for re
[...] [...]
---- ----
It means that the hostname you set for corosync 'ringX_addr' in the It means that the hostname you set for a corosync 'ringX_addr' in the
configuration could not be resolved. configuration could not be resolved.
Write Configuration When Not Quorate Write Configuration When Not Quorate
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
If you need to change '/etc/pve/corosync.conf' on an node with no quorum, and you If you need to change '/etc/pve/corosync.conf' on a node with no quorum, and you
know what you do, use: understand what you are doing, use:
[source,bash] [source,bash]
---- ----
pvecm expected 1 pvecm expected 1
---- ----
This sets the expected vote count to 1 and makes the cluster quorate. You can This sets the expected vote count to 1 and makes the cluster quorate. You can
now fix your configuration, or revert it back to the last working backup. then fix your configuration, or revert it back to the last working backup.
This is not enough if corosync cannot start anymore. Here it is best to edit the This is not enough if corosync cannot start anymore. In that case, it is best to
local copy of the corosync configuration in '/etc/corosync/corosync.conf' so edit the local copy of the corosync configuration in
that corosync can start again. Ensure that on all nodes this configuration has '/etc/corosync/corosync.conf', so that corosync can start again. Ensure that on
the same content to avoid split brains. If you are not sure what went wrong all nodes, this configuration has the same content to avoid split-brain
it's best to ask the Proxmox Community to help you. situations.
[[pvecm_corosync_conf_glossary]] [[pvecm_corosync_conf_glossary]]
@ -1211,7 +1209,7 @@ Corosync Configuration Glossary
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ringX_addr:: ringX_addr::
This names the different link addresses for the kronosnet connections between This names the different link addresses for the Kronosnet connections between
nodes. nodes.
@ -1230,7 +1228,7 @@ quorum. Once quorate, it starts all guests which have the `onboot`
flag set. flag set.
When you turn on nodes, or when power comes back after power failure, When you turn on nodes, or when power comes back after power failure,
it is likely that some nodes boots faster than others. Please keep in it is likely that some nodes will boot faster than others. Please keep in
mind that guest startup is delayed until you reach quorum. mind that guest startup is delayed until you reach quorum.
@ -1243,13 +1241,13 @@ migrations. This can be done via the configuration file
`datacenter.cfg` or for a specific migration via API or command line `datacenter.cfg` or for a specific migration via API or command line
parameters. parameters.
It makes a difference if a Guest is online or offline, or if it has It makes a difference if a guest is online or offline, or if it has
local resources (like a local disk). local resources (like a local disk).
For Details about Virtual Machine Migration see the For details about virtual machine migration, see the
xref:qm_migration[QEMU/KVM Migration Chapter]. xref:qm_migration[QEMU/KVM Migration Chapter].
For Details about Container Migration see the For details about container migration, see the
xref:pct_migration[Container Migration Chapter]. xref:pct_migration[Container Migration Chapter].
Migration Type Migration Type
@ -1258,9 +1256,9 @@ Migration Type
The migration type defines if the migration data should be sent over an The migration type defines if the migration data should be sent over an
encrypted (`secure`) channel or an unencrypted (`insecure`) one. encrypted (`secure`) channel or an unencrypted (`insecure`) one.
Setting the migration type to insecure means that the RAM content of a Setting the migration type to insecure means that the RAM content of a
virtual guest gets also transferred unencrypted, which can lead to virtual guest is also transferred unencrypted, which can lead to
information disclosure of critical data from inside the guest (for information disclosure of critical data from inside the guest (for
example passwords or encryption keys). example, passwords or encryption keys).
Therefore, we strongly recommend using the secure channel if you do Therefore, we strongly recommend using the secure channel if you do
not have full control over the network and can not guarantee that no not have full control over the network and can not guarantee that no
@ -1273,33 +1271,33 @@ Encryption requires a lot of computing power, so this setting is often
changed to "unsafe" to achieve better performance. The impact on changed to "unsafe" to achieve better performance. The impact on
modern systems is lower because they implement AES encryption in modern systems is lower because they implement AES encryption in
hardware. The performance impact is particularly evident in fast hardware. The performance impact is particularly evident in fast
networks where you can transfer 10 Gbps or more. networks, where you can transfer 10 Gbps or more.
Migration Network Migration Network
~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~
By default, {pve} uses the network in which cluster communication By default, {pve} uses the network in which cluster communication
takes place to send the migration traffic. This is not optimal because takes place to send the migration traffic. This is not optimal both because
sensitive cluster traffic can be disrupted and this network may not sensitive cluster traffic can be disrupted and this network may not
have the best bandwidth available on the node. have the best bandwidth available on the node.
Setting the migration network parameter allows the use of a dedicated Setting the migration network parameter allows the use of a dedicated
network for the entire migration traffic. In addition to the memory, network for all migration traffic. In addition to the memory,
this also affects the storage traffic for offline migrations. this also affects the storage traffic for offline migrations.
The migration network is set as a network in the CIDR notation. This The migration network is set as a network using CIDR notation. This
has the advantage that you do not have to set individual IP addresses has the advantage that you don't have to set individual IP addresses
for each node. {pve} can determine the real address on the for each node. {pve} can determine the real address on the
destination node from the network specified in the CIDR form. To destination node from the network specified in the CIDR form. To
enable this, the network must be specified so that each node has one, enable this, the network must be specified so that each node has exactly one
but only one IP in the respective network. IP in the respective network.
Example Example
^^^^^^^ ^^^^^^^
We assume that we have a three-node setup with three separate We assume that we have a three-node setup, with three separate
networks. One for public communication with the Internet, one for networks. One for public communication with the Internet, one for
cluster communication and a very fast one, which we want to use as a cluster communication, and a very fast one, which we want to use as a
dedicated network for migration. dedicated network for migration.
A network configuration for such a setup might look as follows: A network configuration for such a setup might look as follows:
@ -1348,7 +1346,7 @@ migration: secure,network=10.1.2.0/24
---- ----
NOTE: The migration type must always be set when the migration network NOTE: The migration type must always be set when the migration network
gets set in `/etc/pve/datacenter.cfg`. is set in `/etc/pve/datacenter.cfg`.
ifdef::manvolnum[] ifdef::manvolnum[]