Document that virtio-scsi is the recommended controller for PVE >= 4.3

[pve-docs.git] / ha-manager.adoc

diff --git a/ha-manager.adoc b/ha-manager.adoc
index 78bbf10ecafd76ed405a77c48b92cc47bf9ea2db..5db5b052e44d3f1817298a284ca8b65efc8eadca 100644 (file)
--- a/ha-manager.adoc
+++ b/ha-manager.adoc
@@ -215,7 +215,7 @@ then executes this action *one time* and writes back the result, also
 identifiable by the same UID. This is needed so that the LRM does not
 executes an outdated command.
 With the exception of the 'stop' and the 'error' command,
-those two do not depend on the result produce and are executed
+those two do not depend on the result produced and are executed
 always in the case of the stopped state and once in the case of
 the error state.
 
@@ -346,9 +346,27 @@ Configure Hardware Watchdog
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 By default all watchdog modules are blocked for security reasons as they are
 like a loaded gun if not correctly initialized.
-If you have a hardware watchdog available remove its module from the blacklist
-and restart 'the watchdog-mux' service.
-
+If you have a hardware watchdog available remove its kernel module from the
+blacklist, load it with insmod and restart the 'watchdog-mux' service or reboot
+the node.
+
+Recover Fenced Services
+~~~~~~~~~~~~~~~~~~~~~~~
+
+After a node failed and its fencing was successful we start to recover services
+to other available nodes and restart them there so that they can provide service
+again.
+
+The selection of the node on which the services gets recovered is influenced
+by the users group settings, the currently active nodes and their respective
+active service count.
+First we build a set out of the intersection between user selected nodes and
+available nodes. Then the subset with the highest priority of those nodes
+gets chosen as possible nodes for recovery. We select the node with the
+currently lowest active service count as a new node for the service.
+That minimizes the possibility of an overload, which else could cause an
+unresponsive node and as a result a chain reaction of node failures in the
+cluster.
 
 Groups
 ------
@@ -360,7 +378,11 @@ Group Settings
 
 nodes::
 
-list of group node members
+List of group node members where a priority can be given to each node.
+A service bound to this group will run on the nodes with the highest priority
+available. If more nodes are in the highest priority class the services will
+get distributed to those node if not already there. The priorities have a
+relative meaning only.
 
 restricted::
 
@@ -374,10 +396,19 @@ the resource won't automatically fail back when a more preferred node
 (re)joins the cluster.
 
 
-Recovery Policy
----------------
+Start Failure Policy
+---------------------
+
+The start failure policy comes in effect if a service failed to start on a
+node once ore more times. It can be used to configure how often a restart
+should be triggered on the same node and how often a service should be
+relocated so that it gets a try to be started on another node.
+The aim of this policy is to circumvent temporary unavailability of shared
+resources on a specific node. For example, if a shared storage isn't available
+on a quorate node anymore, e.g. network problems, but still on other nodes,
+the relocate policy allows then that the service gets started nonetheless.
 
-There are two service recover policy settings which can be configured
+There are two service start recover policy settings which can be configured
 specific for each resource.
 
 max_restart::
@@ -450,7 +481,8 @@ Service States
 
 stopped::
 
-Service is stopped (confirmed by LRM)
+Service is stopped (confirmed by LRM), if detected running it will get stopped
+again.
 
 request_stop::
 
@@ -459,11 +491,14 @@ Service should be stopped. Waiting for confirmation from LRM.
 started::
 
 Service is active an LRM should start it ASAP if not already running.
+If the Service fails and is detected to be not running the LRM restarts it.
 
 fence::
 
 Wait for node fencing (service node is not inside quorate cluster
 partition).
+As soon as node gets fenced successfully the service will be recovered to
+another node, if possible.
 
 freeze::