X-Git-Url: https://git.proxmox.com/?p=pve-docs.git;a=blobdiff_plain;f=ha-manager.adoc;h=8e50524d7b97a3165f08a54856fbba4a44618fad;hp=321fa3d43cdf50935db7a65f018bb783d8c9b64c;hb=b5266e9f29b55f075bd0c7dbc4be6e7d014474c3;hpb=22653ac84b2ffc3613ebac10b4b8a2b44d197e5f diff --git a/ha-manager.adoc b/ha-manager.adoc index 321fa3d..8e50524 100644 --- a/ha-manager.adoc +++ b/ha-manager.adoc @@ -7,7 +7,7 @@ include::attributes.txt[] NAME ---- -ha-manager - Proxmox VE HA manager command line interface +ha-manager - Proxmox VE HA Manager SYNOPSYS -------- @@ -24,26 +24,180 @@ High Availability include::attributes.txt[] endif::manvolnum[] + +Our modern society depends heavily on information provided by +computers over the network. Mobile devices amplified that dependency, +because people can access the network any time from anywhere. If you +provide such services, it is very important that they are available +most of the time. + +We can mathematically define the availability as the ratio of (A) the +total time a service is capable of being used during a given interval +to (B) the length of the interval. It is normally expressed as a +percentage of uptime in a given year. + +.Availability - Downtime per Year +[width="60%",cols="/lrm_status'. There the CRM may collect +it and let its state machine - respective the commands output - act on it. + +The actions on each service between CRM and LRM are normally always synced. +This means that the CRM requests a state uniquely marked by an UID, the LRM +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 This is needed so that the LRM does not +executes an outdated command.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 +always in the case of the stopped state and once in the case of +the error state. + +.Read the Logs +[NOTE] +The HA Stack logs every action it makes. This helps to understand what +and also why something happens in the cluster. Here its important to see +what both daemons, the LRM and the CRM, did. You may use +`journalctl -u pve-ha-lrm` on the node(s) where the service is and +the same command for the pve-ha-crm on the node which is the current master. + +Cluster Resource Manager +~~~~~~~~~~~~~~~~~~~~~~~~ The cluster resource manager ('pve-ha-crm') starts on each node and waits there for the manager lock, which can only be held by one node at a time. The node which successfully acquires the manager lock gets -promoted to the CRM, it handles cluster wide actions like migrations -and failures. +promoted to the CRM master. + +It can be in three states: TODO + +* *wait for agent lock*: the LRM waits for our exclusive lock. This is + also used as idle sate if no service is configured +* *active*: the LRM holds its exclusive lock and has services configured +* *lost agent lock*: the LRM lost its lock, this means a failure happened + and quorum was lost. + +It main task is to manage the services which are configured to be highly +available and try to get always bring them in the wanted state, e.g.: a +enabled service will be started if its not running, if it crashes it will +be started again. Thus it dictates the LRM the wanted actions. When an node leaves the cluster quorum, its state changes to unknown. If the current CRM then can secure the failed nodes lock, the services @@ -54,7 +208,7 @@ quorum, the LRM waits for a new quorum to form. As long as there is no quorum the node cannot reset the watchdog. This will trigger a reboot after 60 seconds. -CONFIGURATION +Configuration ------------- The HA stack is well integrated int the Proxmox VE API2. So, for @@ -66,18 +220,44 @@ The resource configuration file can be located at '/etc/pve/ha/groups.cfg'. Use the provided tools to make changes, there shouldn't be any need to edit them manually. -RESOURCES/SERVICES AGENTS +Node Power Status +----------------- + +If a node needs maintenance you should migrate and or relocate all +services which are required to run always on another node first. +After that you can stop the LRM and CRM services. But note that the +watchdog triggers if you stop it with active services. + +Fencing +------- + +What Is Fencing +~~~~~~~~~~~~~~~ + +Fencing secures that on a node failure the dangerous node gets will be rendered +unable to do any damage and that no resource runs twice when it gets recovered +from the failed node. + +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. + + +Resource/Service Agents ------------------------- A resource or also called service can be managed by the ha-manager. Currently we support virtual machines and container. -GROUPS +Groups ------ A group is a collection of cluster nodes which a service may be bound to. -GROUP SETTINGS +Group Settings ~~~~~~~~~~~~~~ nodes:: @@ -96,7 +276,7 @@ the resource won't automatically fail back when a more preferred node (re)joins the cluster. -RECOVERY POLICY +Recovery Policy --------------- There are two service recover policy settings which can be configured @@ -118,7 +298,7 @@ service had at least one successful start. That means if a service is re-enabled without fixing the error only the restart policy gets repeated. -ERROR RECOVERY +Error Recovery -------------- If after all tries the service state could not be recovered it gets @@ -136,7 +316,7 @@ killing its process) * *after* you fixed all errors you may enable the service again -SERVICE OPERATIONS +Service Operations ------------------ This are how the basic user-initiated service operations (via @@ -167,7 +347,7 @@ start and stop commands can be issued to the resource specific tools service state (enabled, disabled). -SERVICE STATES +Service States -------------- stopped::