Identifying virtual machines with Raw Device Mappings (RDMs)

Products

• VMware vSphere ESXi

Issue/Introduction

This article provides steps to identify Raw Device Mappings (RDMs) attached to registered virtual machines.

Environment

VMware vSphere ESXi (All Versions)

Resolution

To identify RDMs using the vSphere Client:

1. Determine which RDM LUNs are part of a VM cluster. From the vSphere Client, select a virtual machine that has a mapping to the RDM devices.
2. Edit your virtual machine settings and navigate to your Mapped RAW LUNs. In this example, Hard disk 2:
   
   
3. The RDM physical path is identified from the vml ID via Physical LUN.
4. Take note of the vml ID, which is a globally unique identifier for your shared device.
5. Identify the naa.id for this vml through the command "esxcli storage core device list"

esxcli storage core device list

naa.6589cfc000000a17ac02aae02067e747
   Display Name: FreeNAS iSCSI Disk (naa.6589cfc000000a17ac02aae02067e747)
   Has Settable Display Name: true
   Size: 40960
   Device Type: Direct-Access
   Multipath Plugin: NMP
   Devfs Path: /vmfs/devices/disks/naa.6589cfc000000a17ac02aae02067e747
   Vendor: FreeNAS
   Model: iSCSI Disk
   Revision: 0123
   SCSI Level: 6
   Is Pseudo: false
   Status: degraded
   Is RDM Capable: true
   Is Local: false
   Is Removable: false
   Is SSD: false
   Is VVOL PE: false
   Is Offline: false
   Is Perennially Reserved: false
   Queue Full Sample Size: 0
   Queue Full Threshold: 0
   Thin Provisioning Status: unknown
   Attached Filters:
   VAAI Status: supported
   Other UIDs: vml.010001000030303530353630313031303830310000695343534920
   Is Shared Clusterwide: true
   Is SAS: false
   Is USB: false
   Is Boot Device: false
   Device Max Queue Depth: 128
   No of outstanding IOs with competing worlds: 32
   Drive Type: unknown
   RAID Level: unknown
   Number of Physical Drives: unknown
   Protection Enabled: false
   PI Activated: false
   PI Type: 0
   PI Protection Mask: NO PROTECTION
   Supported Guard Types: NO GUARD SUPPORT
   DIX Enabled: false
   DIX Guard Type: NO GUARD SUPPORT
   Emulated DIX/DIF Enabled: false
 

To identify RDMs using ESXi CLI:

1. Open a SSH session to the ESXi host. 
    
2. Run the below commands:
   
   #find /vmfs/volumes/ -type f -name '*.vmdk' -size -1024k -exec grep -l '^createType=.*RawDeviceMap' {} \; > /tmp/rdmsluns.txt
   
   #for i in `cat /tmp/rdmsluns.txt`; do vmkfstools -q $i; done
   
   Example output:
    
   • Virtual Mode RDM:
     
     Disk /vmfs/volumes/.../virtualrdm.vmdk is a Non-passthrough Raw Device Mapping
Maps to: vml.02000000006006048000019030091953303030313253594d4d4554
      
   • Physical Mode RDM:
     
     Disk /vmfs/volumes/.../physicalrdm.vmdk is a Passthrough Raw Device Mapping
Maps to: vml.02000000006006048000019030091953303030313253594d4d4554
   
   
   

To identify RDMs using PowerCLI

1. Open the vSphere PowerCLI command-line.
    
2. Run the command:
   
   Get-VM | Get-HardDisk -DiskType "RawPhysical","RawVirtual" | Select Parent,Name,DiskType,ScsiCanonicalName,DeviceName | fl
   
   This command produces a list of virtual machines with RDMs, along with the backing SCSI device for the RDMs.
   
   An output looks similar to:
    

   Parent	Virtual Machine Display Name
   Name	Hard Disk n
   DiskType	RawVirtual
   ScsiCanonicalName	naa.60123456789abcdef0123456789abcde
   DeviceName	vml.020000000060123456789abcdef0123456789abcde1234567890ab

   
   If you need to save the output to a file the command can be modified:
   
   Get-VM | Get-HardDisk -DiskType "RawPhysical","RawVirtual" | Select Parent,Name,DiskType,ScsiCanonicalName,DeviceName | fl | Out-File –FilePath RDM-list.txt
3. Identify the backing SCSI device from either the ScsiCanonicalName or DeviceName identifiers. 

Additional Information

For more information, see Identifying disks when working with VMware ESXi