What is the requirement to configure I/O fencing on Virtual Machines.

  • Article ID:100004580
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Problem

Virtual Machines were added to an existing cluster with physical nodes. When vxfen was started it failed.

Error Message

vxfen log showed following errors.

Tue Jan 11 20:30:32 GMT+8 2011 output was VXFEN vxfenconfig ERROR V-11-2-1006 List of coordinator disks in running

 cluster is different than local node.

 Unable to configure vxfen

Log Buffer: 0xffffffff889b5f40

VXFEN vxfenconfig NOTICE Driver will use SCSI-3 compliant disks.

Tue Jan 11 20:30:32 GMT+8 2011 exiting with 1

Cause

Virtual machine and IO fencing should be configured in a particular way.

Solution

IO fencing and Virtual Machines should be configured as below;

SCSI-3 Persistent reservations are only supported with raw device mapping (RDM) in physical mode. I/O fencing is not supported with RDM logical mode or with VMDK-based virtual disks. I/O fencing utilizes HBA World Wide Numbers (WWNs) to create registrations on the storage; this has implications in a virtual environment where the HBA is shared between virtual servers on the same physical ESX host as the WWN used for I/O fencing ends up being the same for each virtual machine. CFS virtual machines (in the same CFS cluster) cannot share physical servers as the I/O fencing behavior will result in all nodes from that physical ESX host being fenced out if an event triggers the fencing functionality. In short, if I/O fencing is configured, the CFS nodes (in the same CFS cluster) has to be running on separate physical ESX hosts. NPIV is currently under evaluation for I/O fencing testing when using multiple Virtual Machines on the same physical ESX host.

 

 

 

Applies To

Suse 10

vcs 5.1

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