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1.3. Cluster Infrastructure
- Cluster management
- Lock management
- Cluster configuration management
1.3.1. Cluster Management
Figure 1.2. CMAN/DLM Overview
1.3.2. Lock Management
fenced, when notified of the failure, fences the failed node. Other cluster-infrastructure components determine what actions to take — that is, they perform any recovery that needs to done. For example, DLM and GFS, when notified of a node failure, suspend activity until they detect that
fencedhas completed fencing the failed node. Upon confirmation that the failed node is fenced, DLM and GFS perform recovery. DLM releases locks of the failed node; GFS recovers the journal of the failed node.
- Power fencing — A fencing method that uses a power controller to power off an inoperable node. Two types of power fencing are available: external and integrated. External power fencing powers off a node via a power controller (for example an API or a WTI power controller) that is external to the node. Integrated power fencing powers off a node via a power controller (for example,IBM Bladecenters, PAP, DRAC/MC, HP ILO, IPMI, or IBM RSAII) that is integrated with the node.
- SCSI3 Persistent Reservation Fencing — A fencing method that uses SCSI3 persistent reservations to disallow access to shared storage. When fencing a node with this fencing method, the node's access to storage is revoked by removing its registrations from the shared storage.
- Fibre Channel switch fencing — A fencing method that disables the Fibre Channel port that connects storage to an inoperable node.
- GNBD fencing — A fencing method that disables an inoperable node's access to a GNBD server.
Figure 1.3. Power Fencing Example
Figure 1.4. Fibre Channel Switch Fencing Example
Figure 1.5. Fencing a Node with Dual Power Supplies
Figure 1.6. Fencing a Node with Dual Fibre Channel Connections
1.3.4. Cluster Configuration System
Figure 1.7. CCS Overview
Figure 1.8. Accessing Configuration Information
/etc/cluster/cluster.conf) is an XML file that describes the following cluster characteristics:
- Cluster name — Displays the cluster name, cluster configuration file revision level, and basic fence timing properties used when a node joins a cluster or is fenced from the cluster.
- Cluster — Displays each node of the cluster, specifying node name, node ID, number of quorum votes, and fencing method for that node.
- Fence Device — Displays fence devices in the cluster. Parameters vary according to the type of fence device. For example for a power controller used as a fence device, the cluster configuration defines the name of the power controller, its IP address, login, and password.
- Managed Resources — Displays resources required to create cluster services. Managed resources includes the definition of failover domains, resources (for example an IP address), and services. Together the managed resources define cluster services and failover behavior of the cluster services.