general, a HA managed resource should not depend on other resources.
+Management Tasks
+----------------
+
+This section provides a short overview of common management tasks. The
+first step is to enable HA for a resource. This is done by adding the
+resource to the HA resource configuration. You can do this using the
+GUI, or simply use the command line tool, for example:
+
+----
+# ha-manager add vm:100
+----
+
+The HA stack now tries to start the resources and keeps it
+running. Please note that you can configure the ``requested''
+resources state. For example you may want that the HA stack stops the
+resource:
+
+----
+# ha-manager set vm:100 --state stopped
+----
+
+and start it again later:
+
+----
+# ha-manager set vm:100 --state started
+----
+
+You can also use the normal VM and container management commands. They
+automatically forward the commands to the HA stack, so
+
+----
+# qm start 100
+----
+
+simply sets the requested state to `started`. Same applied to `qm
+stop`, which sets the requested state to `stopped`.
+
+NOTE: The HA stack works fully asynchronous and needs to communicate
+with other cluster members. So it takes some seconds until you see
+the result of such actions.
+
+To view the current HA resource configuration use:
+
+----
+# ha-manager config
+vm:100
+ state stopped
+----
+
+And you can view the actual HA manager and resource state with:
+
+----
+# ha-manager status
+quorum OK
+master node1 (active, Wed Nov 23 11:07:23 2016)
+lrm elsa (active, Wed Nov 23 11:07:19 2016)
+service vm:100 (node1, started)
+----
+
+You can also initiate resource migration to other nodes:
+
+----
+# ha-manager migrate vm:100 node2
+----
+
+This uses online migration and tries to keep the VM running. Online
+migration needs to transfer all used memory over the network, so it is
+sometimes faster to stop VM, then restart it on the new node. This can be
+done using the `relocate` command:
+
+----
+# ha-manager relocate vm:100 node2
+----
+
+Finally, you can remove the resource from the HA configuration using
+the following command:
+
+----
+# ha-manager remove vm:100
+----
+
+NOTE: This does not start or stop the resource.
+
+But all HA related task can be done on the GUI, so there is no need to
+use the command line at all.
+
+
How It Works
------------
[NOTE]
Locks are provided by our distributed configuration file system (pmxcfs).
They are used to guarantee that each LRM is active once and working. As a
-LRM only executes actions when it holds its lock we can mark a failed node
+LRM only executes actions when it holds its lock, we can mark a failed node
as fenced if we can acquire its lock. This lets us then recover any failed
HA services securely without any interference from the now unknown failed node.
This all gets supervised by the CRM which holds currently the manager master
Service States
~~~~~~~~~~~~~~
-[thumbnail="gui-ha-manager-status.png"]
-
The CRM use a service state enumeration to record the current service
state. We display this state on the GUI and you can query it using
the `ha-manager` command line tool:
Service should be stopped. The CRM waits for confirmation from the
LRM.
+stopping::
+
+Pending stop request. But the CRM did not get the request so far.
+
started::
Service is active an LRM should start it ASAP if not already running.
restarts it
(see xref:ha_manager_start_failure_policy[Start Failure Policy]).
+starting::
+
+Pending start request. But the CRM has not got any confirmation from the
+LRM that the service is running.
+
fence::
Wait for node fencing (service node is not inside quorate cluster
node, or when we restart the LRM daemon
(see xref:ha_manager_package_updates[Package Updates]).
+ignored::
+
+Act as if the service were not managed by HA at all.
+Useful, when full control over the service is desired temporarily,
+without removing it from the HA configuration.
+
+
migrate::
Migrate service (live) to other node.
Service is disabled because of LRM errors. Needs manual intervention
(see xref:ha_manager_error_recovery[Error Recovery]).
+queued::
+
+Service is newly added, and the CRM has not seen it so far.
+
+disabled::
+
+Service is stopped and marked as `disabled`
+
Local Resource Manager
~~~~~~~~~~~~~~~~~~~~~~
Resources
~~~~~~~~~
-[thumbnail="gui-ha-manager-resources-view.png"]
+[thumbnail="gui-ha-manager-status.png"]
+
The resource configuration file `/etc/pve/ha/resources.cfg` stores
the list of resources managed by `ha-manager`. A resource configuration
include::ha-resources-opts.adoc[]
Here is a real world example with one VM and one container. As you see,
-the syntax of those files is really simple, so it is even posiible to
+the syntax of those files is really simple, so it is even possible to
read or edit those files using your favorite editor:
.Configuration Example (`/etc/pve/ha/resources.cfg`)
[thumbnail="gui-ha-manager-add-group.png"]
-A commom requirement is that a resource should run on a specific
+A common requirement is that a resource should run on a specific
node. Usually the resource is able to run on other nodes, so you can define
an unrestricted group with a single member:
For bigger clusters, it makes sense to define a more detailed failover
behavior. For example, you may want to run a set of services on
`node1` if possible. If `node1` is not available, you want to run them
-equally splitted on `node2` and `node3`. If those nodes also fail the
+equally split on `node2` and `node3`. If those nodes also fail the
services should run on `node4`. To achieve this you could set the node
list to:
The `nofailback` options is mostly useful to avoid unwanted resource
-movements during administartion tasks. For example, if you need to
+movements during administration tasks. For example, if you need to
migrate a service to a node which hasn't the highest priority in the
group, you need to tell the HA manager to not move this service
instantly back by setting the `nofailback` option.
the LRM makes a request to the CRM to freeze all its services. This prevents
that they get touched by the Cluster during the short time the LRM is restarting.
After that the LRM may safely close the watchdog during a restart.
-Such a restart happens on a update and as already stated a active master
-CRM is needed to acknowledge the requests from the LRM, if this is not the case
-the update process can be too long which, in the worst case, may result in
-a watchdog reset.
+Such a restart happens normally during a package update and, as already stated,
+an active master CRM is needed to acknowledge the requests from the LRM. If
+this is not the case the update process can take too long which, in the worst
+case, may result in a reset triggered by the watchdog.
Node Maintenance
The LRM tells the CRM that it wants to restart, and waits until the
CRM puts all resources into the `freeze` state (same mechanism is used
-for xref:ha_manager_package_updates[Pakage Updates]). This prevents
+for xref:ha_manager_package_updates[Package Updates]). This prevents
that those resources are moved to other nodes. Instead, the CRM start
the resources after the reboot on the same node.
in a node reboot.
-[[ha_manager_service_operations]]
-Service Operations
-------------------
-
-This are how the basic user-initiated service operations (via
-`ha-manager`) work.
-
-set state::
-
-Request the service state.
-See xref:ha_manager_resource_config[Resource Configuration] for possible
-request states.
-+
-----
-# ha-manager set SID -state REQUEST_STATE
-----
-
-disable::
-
-The service will be placed in the stopped state, even if it was in the error
-state. The service will not be recovered on a node failure and will stay
-stopped while it is in this state.
-
-migrate/relocate::
-
-The service will be relocated (live) to another node.
-
-remove::
-
-The service will be removed from the HA managed resource list. Its
-current state will not be touched.
-
-start/stop::
-
-`start` and `stop` commands can be issued to the resource specific tools
-(like `qm` or `pct`), they will forward the request to the
-`ha-manager` which then will execute the action and set the resulting
-service state (enabled, disabled).
-
-
ifdef::manvolnum[]
include::pve-copyright.adoc[]
endif::manvolnum[]
projects / pve-docs.git / blobdiff