SCSI Reservation Issue with Fibre Channel HBAs

Products

• VMware vSphere ESXi

Issue/Introduction

When you deploy HBAs connected to low-end storage devices with SCSI reservation enabled in a cluster-node type configuration, you could encounter a situation whereby the Device Reset might not occur as expected. During the transition from one node to another node, the SCSI reservation needs to be cleared before a successful transition. Because most of the low-end storage devices support Target Reset and not LUN Reset, there are some parameters that need to be configured correctly in the ESX Server system.

Environment

VMware ESX Server 2.5.x
VMware ESX 4.1.x
VMware ESX Server 3.5.x
VMware ESX Server 2.1.x
VMware ESX 4.0.x
VMware ESX Server 2.0.x
VMware ESX Server 3.0.x

Resolution

If you encounter the situation above, you can modify a parameter in the ESX Server system to change Device Reset from the default LUN Reset to enable Target Reset.

To change the default parameter in the ESX Server system:

1. Log on to the ESX Server system's service console as root.
   
   
2. The default value for Device Reset is 1, which refers to LUN Reset. Change the value of UseLunReset to 0 to enable Target Reset instead. Type this command:
   
   # esxcfg-advcfg -s 0 /Disk/UseLunReset
   
   
3. View the file to make sure UseLunReset is set to 0:
   
   # esxcfg-advcfg -g /Disk/UseLunReset