About I/O fencing configuration files

Table: I/O fencing configuration files lists the I/O fencing configuration files.

Table: I/O fencing configuration files




This file stores the start and stop environment variables for I/O fencing:

  • VXFEN_START - Defines the startup behavior for the I/O fencing module after a system reboot. Valid values include:

    1 - Indicates that I/O fencing is enabled to start up.

    0 - Indicates that I/O fencing is disabled to start up.

  • VXFEN_STOP - Defines the shutdown behavior for the I/O fencing module during a system shutdown. Valid values include:

    1 - Indicates that I/O fencing is enabled to shut down.

    0 - Indicates that I/O fencing is disabled to shut down.

The installer sets the value of these variables to 1 at the end of VCS configuration.

If you manually configured VCS, you must make sure to set the values of these environment variables to 1.


This file includes the coordinator disk group information.

This file is not applicable for server-based fencing and majority-based fencing.


This file contains the following parameters:

  • vxfen_mode

    • scsi3 - For disk-based fencing.

    • customized - For server-based fencing.

    • disabled - To run the I/O fencing driver but not do any fencing operations.

    • majority - For fencing without the use of coordination points.

  • vxfen_mechanism

    This parameter is applicable only for server-based fencing. Set the value as cps.

  • scsi3_disk_policy

    • dmp - Configure the vxfen module to use DMP devices

      The disk policy is dmp by default. If you use iSCSI devices, you must set the disk policy as dmp.


    You must use the same SCSI-3 disk policy on all the nodes.

  • List of coordination points

    This list is required only for server-based fencing configuration.

    Coordination points in server-based fencing can include coordinator disks, CP servers, or both. If you use coordinator disks, you must create a coordinator disk group containing the individual coordinator disks.

    Refer to the sample file /etc/vxfen.d/vxfenmode_cps for more information on how to specify the coordination points and multiple IP addresses for each CP server.

  • single_cp

    This parameter is applicable for server-based fencing which uses a single highly available CP server as its coordination point. Also applicable for when you use a coordinator disk group with single disk.

  • autoseed_gab_timeout

    This parameter enables GAB automatic seeding of the cluster even when some cluster nodes are unavailable.

    This feature is applicable for I/O fencing in SCSI3 and customized mode.

    0 - Turns the GAB auto-seed feature on. Any value greater than 0 indicates the number of seconds that GAB must delay before it automatically seeds the cluster.

    -1 - Turns the GAB auto-seed feature off. This setting is the default.


When I/O fencing starts, the vxfen startup script creates this /etc/vxfentab file on each node. The startup script uses the contents of the /etc/vxfendg and /etc/vxfenmode files. Any time a system is rebooted, the fencing driver reinitializes the vxfentab file with the current list of all the coordinator points.


The /etc/vxfentab file is a generated file; do not modify this file.

For disk-based I/O fencing, the /etc/vxfentab file on each node contains a list of all paths to each coordinator disk along with its unique disk identifier. A space separates the path and the unique disk identifier. An example of the /etc/vxfentab file in a disk-based fencing configuration on one node resembles as follows:

  • DMP disk:

    /dev/vx/rdmp/sdx3 HITACHI%5F1724-100%20%20FAStT%5FDISKS%5F6
    /dev/vx/rdmp/sdy3 HITACHI%5F1724-100%20%20FAStT%5FDISKS%5F6
    /dev/vx/rdmp/sdz3 HITACHI%5F1724-100%20%20FAStT%5FDISKS%5F6

For server-based fencing, the /etc/vxfentab file also includes the security settings information.

For server-based fencing with single CP server, the /etc/vxfentab file also includes the single_cp settings information.

This file is not applicable for majority-based fencing.