Virtual Machines with RDMs Need to Ignore SCSI INQUIRY Cache

Storage vendors might require that virtual machines with RDMs ignore SCSI INQUIRY data cached by ESXi.

Problem

Certain guest operating systems or applications run in virtual machines with RDMs display unpredictable behavior.

Cause

This behavior might be caused by cached SCSI INQUIRY data that interferes with specific guest operating systems and applications.

When the ESXi host first connects to a target storage device on a SAN, it issues the SCSI INQUIRY command to obtain basic identification data from the device. By default, ESXi caches the received SCSI INQUIRY data (Standard, page 80, and page 83) and the data remains unchanged afterwards.

Solution

• ♦ Configure the virtual machine with RDM to ignore the SCSI INQUIRY cache by adding the following parameter to the .vmx file.

  scsix:y.ignoreDeviceInquiryCache = "true"

  where x is the SCSI controller number and y is the SCSI target number of the RDM.

  Enable this parameter only when your storage vendor recommends that you do so. This parameter is required for just a limited number of storage arrays and only for specific guest operating systems.