Introduction to High-Availability Clusters On Linux And Other Systems

What happens if the network connectivity between the active-node and passive node is down?
The active-node still works, the passive node will try to take over the resources, and we'll have two active nodes, corrupting the data on the disks.
To solve this, clusters use I/O fencing.
One common method of fencing, is using SCSI reservation. Another common method is STONITH.

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