This is an informational event which indicates that the host attempting to start or receive the virtual machine cannot access the device (LUN) backing the raw disk mapping.
For more information on raw device mappings, see the Raw Device Mapping section of the ESX/ESXi Server Configuration Guide for your version.
A raw device mapping file contains metadata, specifically SCSI vital product data (VPD) page 0x83, for uniquely identifying a device. A host attempting to access the physical LUN reads the mapping file metadata, and searches the devices known to the host for a LUN with the same VPD page 0x83 information.
The contents of SCSI VPD page 0x83 should match when requested by all hosts in a vSphere cluster, and the RDM should be accessible by all hosts in the cluster. However, discrepancies in device presentation between hosts in a cluster may lead to different hosts receiving different contents for VPD page 0x83 for the same device. In this case, hosts which did not create the RDM mapping file may be unable to locate the raw device mapping LUN when powering on or migrating a virtual machine.
Note: Cold migrations of powered off virtual machines do not require access to the raw device mapping. Symptoms may be noticed after cold migration, when the virtual machine is powered on.
The VPD page 0x83 information, when available, forms the basis of the unique VML identifier which the ESX/ESXi host assigns to each storage device. This VML identifier should be consistent for a given device across each host in a vSphere cluster.
Identify the device being used for a raw device mapping by its VML identifier, such as by reviewing the contents of /vmfs/devices/disks/
, on each host in a cluster. Compare the VML identifier obtained for the device on each host. For more information, see Identifying disks when working with VMware ESX (1014953).
The highlighted sections of the VML identifiers in this example do not match between the hosts, indicating a LUN with different presentation to each host:
vml.02000500006006048000019010406353303035344553594d4d4554 -> naa.60060480000190104063533030353445
vml.02004d00006006048000019010406353303035344553594d4d4554 -> naa.60060480000190104063533030353445
If one segment of a vSphere Cluster has correct presentation of the LUN being used for a raw device mapping, but other segments do not, the virtual machine operates correctly only within the segment with correct presentation. Correct the presentation in the nonworking segment(s):
If the LUN has been flagged as perennially reserved, this can prevent the removal from succeeding.
Run this command to remove the flag:
# esxcli storage core device setconfig -d NAA_ID --perennially-reserved=false
Now the command to remove the device should work.
# esxcli storage core device detached remove -d NAA_ID
There is no harm in setting the flag to false, even if it is not needed, so it might be simpler to always run both commands.
If a virtual machine cannot be started on any host in a vSphere Cluster, the presentation to each host may differ from the VPD Page 0x83 information stored within the raw device mapping file. Recreate the mapping file:
The vCenter Server maintains a cache of storage topology information for virtual machines. If this information has become out of sync with the presentation, power operations or migrations initiated from vCenter Server may fail. Remove the affected virtual machine from inventory and re-register it to clear the cached information: