In a traditional I/O fencing implementation, where the coordination points are coordination point servers (CP servers) or coordinator disks, Clustered Volume Manager (CVM) and Veritas I/O fencing modules provide SCSI-3 persistent reservation (SCSI-3 PR) based protection on the data disks. This SCSI-3 PR protection ensures that the I/O operations from the losing node cannot reach a disk that the surviving sub-cluster has already taken over.

In virtualized environments that do not support SCSI-3 PR, SFCFSHA attempts to provide reasonable safety for the data disks. SFCFSHA requires you to configure non-SCSI-3 I/O fencing in such environments. Non-SCSI-3 fencing either uses server-based I/O fencing with only CP servers as coordination points or majority-based I/O fencing, which does not use coordination points, along with some additional configuration changes to support such environments.