=====CRM manual Putting cluster in maintenance mode for a maintenance activity on the SAP servers.
Many times there will be a need to do some kind of maintenance of a SAP server like OS patching, kernel upgrade, SID stacking etc.
In cases like these you might need to restart the servers but if the servers/nodes are in the cluster then the pacemaker will start migrating the services which can create a setback for the administrators. To avoid such scenarios we can simply put the cluster or a particular node in maintenance mode to avoid unwanted resource migrations.
There are three ways to achieve this depending on the situation.
Put the cluster in maintenance mode
crm configure property maintenance-mode="true"
Put the node in maintenance mode
crm node maintenance <node>
Put the node in standby mode
crm node standby <node>
==Once the activity is completed move the cluster or node out of maintenance using below commands.
Move the cluster out of maintenance
crm configure property maintenance-mode="false"
Move the node out of maintenance
crm node ready <node>
Move the node out of standby
crm node online <node>
====Most Important Commands for managing a pacemaker cluster
CRM monitoring commands-
-> crm status : Check the status of the cluster and its services.
-> crm_mon : Live nonitoring of the cluster
CRM Node Commands
-> crm node show : list the nodes in the cluster.
-> crm node standby <node name> : put a node on standby
-> crm node fence <node name> : fence a particular node. (Restart)
-> crm node online <node name> : bring a node online after standby.
-> crm node clearstate <node> : clear a nodes state. (if in error)
-> crm node maintenance <node> : put the node in maintenance mode. Will not affect the cluster services or resources
-> crm node ready <node> : put the node out of maintenance
CRM Cluster Commands
-> crm cluster health : Check the health of the cluster.
-> crm cluster start : Start cluster services on the node.
-> crm cluster stop : Stop cluster services on the node.
-> crm cluster restart : Restart cluster services on the node.
-> crm cluster status : Show cluster services on this node.
CRM Resource Commands
-> crm resource status <name> : Check status of the resource
-> crm resource start <name> : Start the resource.
-> crm resource stop <name> : Stop the resource.
-> crm resource cleanup <name> : Cleanup the resource.(if in error)
-> crm resource migrate <name> <node> : Migrate the resource from this node to another.
==special thank you
https://www.linkedin.com/pulse/everything-you-need-know-sap-pacemaker-cluster-testing-robin-singh/
