What makes up the pacemaker cluster?
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Website: http://clusterlabs.org
Pacemaker is a cluster manager.
These are the top-level components that make up the pacemaker stack.
These are the internal components
You can see from the internal components there are various components that provide the messaging, cluster membership and quorum. Different linux OS's may use one of these.
The top diagram show the stack with Distributed Lock Manager (DLM) can interface with various types of filesystem technology.
Cluster Information Base (CIB)
Uses XML to manage the cluster configurationCluster Resource Management daemon (CRMd)
Many times the meaning is in the name. There is alway one master CRMd running, on the Designated Controller (DC)Local Resource Management daemon (LRMd)
The difference between CRMd and this is resource management to a node, gets picked up my CRMd first and then passed to LRMd.Policy Engine (PEngine or PE)
Determines the ideal state of the cluster, with reference to the CIB.Fencing daemon (STONITHd)
If something bad happens to a cluster node, to protect the data integrity, this service takes manage taking node offline (powering off) automatically.Pacemaker clusters can run in a number of different configurations: Active/Active, Active/Passive, N+1, N+M, N-to-1 and N-to-N. In an Active/Active every node can be potentially used for failover. For example 4 nodes cluster running four different websites, on failure of a node, the website (resources) can be switched to any other remaining node. This configuration makes use of all machines.
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