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All nodes in the cluster have an access to a shared storage via ceph Ceph (see Shared storage section). With it, the cluster is in N to N redundancy mode.

• Corosync will provides messaging and membership services.
• Pacemaker will manage the cluster (synchronize resources between each node).

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More details on pacemaker Pacemaker here and corosync here.Corosync here.

pacemaker-remote

pacemaker-remote is a component which can be installed inside a VM to allow Pacemaker to manage and monitor resources inside this VM.

For instance, with pacemaker-remote pacemaker can monitor services and containers directly inside a VM.

For more information about pacemaker-remote refer to https://clusterlabs.org/pacemaker/doc/2.1/Pacemaker_Remote/singlehtml/.

Management tool

The vm_manager project is an high-level interface of pacemaker and ceph Ceph to manage the VM like a resource. He is installed during the installation step and provides the vm-mgr command.

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• add_colocation: Adds a colocation constraints constraint between resources

• clone: Creates a copy of the VM

• create: Generates a new resource from a VM

• create_snapshot: Creates a snapshot of a resource

• disable: Stops and removes the resource on the cluster

• enable: Adds and starts the resource on the cluster

• get_metadata: Gets a metadata of a resource

• list: Lists all resources

• list_metadata: Lists all keys of a resource

• list_snapshots: Lists all created snapshots

• purge: Deletes all snapshots of a resource

• remove: Removes the resource

• remove_snapshot: Removes a snapshot of a resource

• rollback: Rollbacks to a snapshot for a resource

• set_metadata: Sets a metadata of a resource

• start: Start a resource

• status: Gets the status of a resource

• stop: Stops a resource

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