VMware RDM(Raw device mapping) disc accessibility issues

  • 7022974
  • 17-May-2018
  • 17-May-2018

Environment

SUSE Linux Enterprise Server 12
SUSE Linux Enterprise Server 12 for SAP
Open Enterprise Server 2018 (OES 2018) Linux

Situation

Issues acessing some RDM devices depending on standby path
Inability to read/write RDM discs although they are visible (failing dd if=/dev/sdx of=/tmp/some count=1)
Other similar issues

Resolution

Configure the virtual machine with RDM to ignore the SCSI INQUIRY cache by adding the following parameter:
scsix:y.ignoreDeviceInquiryCache = "true"

to the .vmx configuration file on your ESXi server.

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.

Additional Information

https://docs.vmware.com/en/VMware-vSphere/6.5/com.vmware.vsphere.troubleshooting.doc/GUID-2852DA1C-507B-4B85-B211-B5CD3C8DC6F2.html

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