1、RHEL 6 集群配置官方管理手册
2、官方讲解Fencing设备原理
-- 部分摘要
Fencing is the disconnection of a node from the cluster's shared storage. Fencing cuts off I/O from shared storage, thus ensuring data integrity. The cluster infrastructure performs fencing through the fence daemon, fenced.
When CMAN determines that a node has failed, it communicates to other cluster-infrastructure components that the node has failed. 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 be done.
For example, DLM and GFS2, when notified of a node failure, suspend activity until they detect that fenced has completed fencing the failed node.
Upon confirmation that the failed node is fenced, DLM and GFS2 perform recovery. DLM releases locks of the failed node; GFS2 recovers the journal of the failed node.
The fencing program determines from the cluster configuration file which fencing method to use. Two key elements in the cluster configuration file define a fencing method: fencing agent and fencing device.
The fencing program makes a call to a fencing agent specified in the cluster configuration file. The fencing agent, in turn, fences the node via a fencing device. When fencing is complete, the fencing program notifies the cluster manager.
The High Availability Add-On provides a variety of fencing methods:
Power fencing — A fencing method that uses a power controller to power off an inoperable node.
storage fencing — A fencing method that disables the Fibre Channel port that connects storage to an inoperable node.
Other fencing — Several other fencing methods that disable I/O or power of an inoperable node, including IBM Bladecenters, PAP, DRAC/MC, HP ILO, IPMI, IBM RSA II, and others.
2015-03-07