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Configuring I/O fencing in the Share Out mode

In Share Out mode, Volume Client systems use I/O fencing with coordinator volumes as described above. Volume Server systems, however, use I/O fencing with coordinator disks.

  Note   You cannot use coordinator volume and coordinator disks together for I/O fencing on the same system or in the same cluster.

See Setting up I/O fencing.

See About I/O fencing in a SFVS environment.

Creating coordinator volumes

The following steps are to be executed on a volume server system:

1. Create a SAN disk group.

   vxdg -o dgtype=san init sample_cvol_dg newdg01=Disk_1

   Where sample_cvol_dg is the disk group name; and the disk group is of a SAN type.

2. Create the coordinator volume in the coordinator disk group. Use the following command:

   vxassist -g sample_cvol_dg make sample_cvol 10m

   Where sample_cvol_dg is the disk group name; sample_cvol is the SAN volume, and 10m is the size of the volume.

3. Export the SAN volumes to all volume clients in the cluster with read-write permissions.
   vxadm -g sample_cvol_dg volume export sample_cvol vcssysA.veritas.com exportperms=RDWR
   

   Where vcssysA.veritas.com is a Volume Client system that the SAN volume sample_cvol is being exported to.

Once you have set up the coordinator volume, you need to initialize it using the /opt/VRTSvcs/vxfen/bin/vxfencvol utility. Attach the SAN volume, and then initialize it with the following commands:

 To attach the SAN volume and initialize the volume

1. Attach the coordinator volume on a Volume Client with read-write permissions.
   vxadm -g sample_cvol_dg volume attach sample_cvol sysA.example.com access_policy=RDWR io_access=ANY
   
2. Initialize the coordinator volume.
   /opt/VRTSvcs/vxfen/bin/vxfencvol -init -cvol /dev/vx/rdsk/vol_server/sample_cvol_dg/sample_cvol
   
3. After initialization, unattach the coordinator volume.
   vxadm -g sample_cvol_dg volume unattach sample_cvol sysA.example.com.
   

Editing the vxfenmode file

Before you start to modify the vxfenmode file, you must stop fencing. You then need to modify the vxfenmode file. The file is in /etc/vxfenmode.

 To edit the vxfenmode file

The following code is a sample configuration for SANVM in the vxfenmode file:

vxfen_mode=customized

vxfen_mechanism=sanvm

disk_group=example_cvol_dg

cvol_name=example_cvol

vs_host=vol_server.example.com

Where the:

• disk_group is the name of the SAN disk group that you want to use when configuring I/O fencing for a SANVM environment.
• cvol_name is the name of the coordinator SAN volume.
• vs_host is the name of the volume server.

 To edit the VCS configuration to add the UseFence attribute

1. Save the existing configuration:

   # haconf -dump -makero

2. Stop VCS on all nodes.

   # hastop -all

3. Make a backup copy of the main.cf file:

   # cd /etc/VRTSvcs/conf/config

   # cp main.cf main.orig

4. On one node, use vi or another text editor to edit the main.cf file. Modify the list of cluster attributes by adding the attribute, UseFence, and assign it a value of SCSI3. For example, with the attribute added this portion of the file resembles:

   cluster vcs_cluster2 (

   UserNames = { admin = "cDRpdxPmHpzS." }

   Administrators = { admin }

   CounterInterval = 5

   UseFence = SCSI3

   )

5. Save and close the file.
6. Verify the syntax of the file /etc/VRTSvcs/conf/config/main.cf:

   # hacf -verify .

7. Using rcp, or some other available utility, copy the VCS configuration file to the other nodes. For example, on each node:

   # rcp north:/etc/VRTSvcs/conf/config/main.cf

   /etc/VRTSvcs/conf/config

8. With the configuration file in place on each system, shut down and then restart each system.

   # reboot

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     Note   To ensure that I/O fencing is shut down properly, use the shutdown command instead of the reboot command.

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