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Adding an RDM LUN to the second node in the MSCS cluster fails with the error: Incompatible device backing specified for device ‘0’ (2054897)

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  • You cannot add an RDM LUN to the second node in a MSCS cluster.
  • Adding an RDM LUN to the second node in a MSCS cluster fails.
  • You see this error:

    Incompatible device backing specified for device ‘0’

  • In the vmware.log file (located in the virtual machine directory), you see entries similar to:

    vmx| TOOLS received request in VMX to set option 'synctime' -> '0'
    vmx| VMAutomation: Hot add device. type=20, backing=100
    vmx| Requesting hot-add of scsi1
    vmx| Hot-adding scsi1
    vmx| HotPlug: Queued scsi1 add.
    vmx| HotPlug: Hot-add of scsi1 failed.
    vmx| Msg_Post: Error
    vmx| [msg.devices.hotadd.failed] Hot-add of scsi1 failed.
    vmx| [msg.devices.hotplug.errMsg] Request aborted
    vmx| [msg.devices.hotplug.failed] The hot-plug operation failed.

  • In the /var/log/hostd.log file, you see entries similar to:

    T14:01:39.091Z [5C736B90 error 'VdisksvcPlugin' opID=E6E3E0B7-0000063D-2] ValidateRawDiskDevice: Couldn't find the device: vml.0200010000600508b40006df850000d001cbb40000485356323030
    2013-02-12T14:01:39.091Z [5C736B90 info 'vm:/vmfs/volumes/4d2bf018-c2b733f2-700a-3c4a926c58c4/Node2/Node2.vmx' opID=E6E3E0B7-0000063D-2] SetDiskProperties: 2TB+ rdm device is not supported: (vim.vm.device.VirtualDisk)

Note: The preceding log excerpts are only examples. Date, time, and environmental variables may vary depending on your environment.


This issue occurs if the RDM LUN ID is not consistent across all ESXi hosts in the cluster.


To resolve this issue, you must ensure that the LUNs are uniformly presented across all ESXi/ESX hosts when sharing MSCS RDM LUNs between the nodes. Specifically, the LUN ID for each LUN must be the same for all ESXi/ESX hosts.
If the LUN IDs are not the same across all ESXi/ESX hosts in the cluster, the mappings must be corrected to a consistent state.

To confirm the issue and correct the LUN mapping for consistency:

  1. Check and make note of the LUN ID that each ESXi/ESX host in the cluster is using to identify the RDM volume. For instructions, see Identifying disks when working with VMware ESX/ESXi (1014953).

  2. Modify the SAN to ESXi/ESX host LUN ID mappings. Contact your storage administrator or storage vendor to assist you in configuring the LUN presentation appropriately. They must present the data LUN(s) with exactly the same LUN ID(s) to all ESXi/ESX hosts.

    Note: It is a better practice to assign the LUN to a new, previously unused LUN ID and present that ID to the cluster, this helps to avoid potential conflicts.

  3. After the LUN ID presentation changes are applied, restart the affected ESXi/ESX hosts to detect the new configuration. You can do this by using a rolling reboot approach, migrating virtual machines off each host in turn using vMotion.

  4. After all ESXi/ESX hosts in the cluster are rebooted, you see a consistent LUN ID across all hosts.

Additional Information

By default, virtual machine log (vmware.log) files are stored in the same directory as the virtual machine configuration (.vmx) file. For more information, see Locating virtual machine log files on an ESXi/ESX host (1007805).

See Also

Update History

10/14/2015 - Added ESXi 6.0 to Products.

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