About I/O fencing

I/O fencing protects the data on shared disks when nodes in a cluster detect a change in the cluster membership that indicates a split-brain condition.

The fencing operation determines the following:

This decision prevents possible data corruption. The installer installs the I/O fencing driver, VRTSvxfen RPM, when you install SFCFSHA. To protect data on shared disks, you must configure I/O fencing after you install and configure SFCFSHA.

I/O fencing technology uses coordination points for arbitration in the event of a network partition.

I/O fencing coordination points can be coordinator disks or coordination point servers (CP servers) or both. You can configure disk-based or server-based I/O fencing:

Disk-based I/O fencing

I/O fencing that uses coordinator disks is referred to as disk-based I/O fencing.

Disk-based I/O fencing ensures data integrity in a single cluster.

Server-based I/O fencing

I/O fencing that uses at least one CP server system is referred to as server-based I/O fencing. Server-based fencing can include only CP servers, or a mix of CP servers and coordinator disks.

Server-based I/O fencing ensures data integrity in clusters.

In virtualized environments that do not support SCSI-3 PR, SFCFSHA supports non-SCSI-3 server-based I/O fencing.

See About I/O fencing for SFCFSHA in virtual machines that do not support SCSI-3 PR.

See About preventing data corruption with I/O fencing.


Symantec recommends that you use I/O fencing to protect your cluster against split-brain situations.

See the Symantec Storage Foundation Cluster File System High Availability Installation Guide.