In the ESXi environment, each storage device is identified by several names.

Device Identifiers

Depending on the type of storage, the ESXi host uses different algorithms and conventions to generate an identifier for each storage device.

Storage-provided identifiers
The ESXi host queries a target storage device for the device name. From the returned metadata, the host extracts or generates a unique identifier for the device. The identifier is based on specific storage standards, is unique and persistent across all hosts, and has one of the following formats:
  • naa.xxx
  • eui.xxx
  • t10.xxx
Path-based identifier
When the device does not provide an identifier, the host generates an mpx. path name, where path represents the first path to the device, for example, mpx.vmhba1:C0:T1:L3. This identifier can be used in the same way as the storage-provided identifies.

The mpx.path identifier is created for local devices on the assumption that their path names are unique. However, this identifier is not unique or persistent, and can change after every system restart.

Typically, the path to the device has the following format:

vmhbaAdapter:CChannel:TTarget:LLUN

  • vmhbaAdapter is the name of the storage adapter. The name refers to the physical adapter on the host, not to the SCSI controller used by the virtual machines.
  • CChannel is the storage channel number.

    Software iSCSI adapters and dependent hardware adapters use the channel number to show multiple paths to the same target.

  • TTarget is the target number. Target numbering is determined by the host and might change when the mappings of targets visible to the host change. Targets that are shared by different hosts might not have the same target number.
  • LLUN is the LUN number that shows the position of the LUN within the target. The LUN number is provided by the storage system. If a target has only one LUN, the LUN number is always zero (0).

For example, vmhba1:C0:T3:L1 represents LUN1 on target 3 accessed through the storage adapter vmhba1 and channel 0.

Legacy identifier
In addition to the device-provided identifiers or mpx. path identifiers, ESXi generates an alternative legacy name for each device. The identifier has the following format:

vml.number

The legacy identifier includes a series of digits that are unique to the device. The identifier can be derived in part from the metadata obtained through the SCSI INQUIRY command. For nonlocal devices that do not provide SCSI INQUIRY identifiers, the vml.number identifier is used as the only available unique identifier.

Displaying Device Names in the vSphere CLI

You can use the esxcli storage core device list command to display all device names in the vSphere CLI. The output is similar to the following example: 

# esxcli storage core device list
naa.XXX
	  Display Name: DGC Fibre Channel Disk(naa.XXX)
	  ... 
	  Other UIDs: vml.000XXX
mpx.vmhba1:C0:T0:L0
   Display Name: Local VMware Disk (mpx.vmhba1:C0:T0:L0)
   ...
   Other UIDs: vml.0000000000XYZ

NVMe Devices with NGUID Device Identifiers

For NVMe devices, ESXi generates device identifiers based on the information it retrieves from the devices. Generally, the NVMe devices support identifiers in EUI64 or NGUID formats, or use both formats. NGUID is a Namespace Globally Unique Identifier that uses the EUI64 16-byte designator format.

For the devices that support only NGUID format, the host creates two identifiers: eui.xxx (NGUID) as primary and t10.xxx_controller_serial_number as alternative primary.

ID Formats Supported by Device Device Identifier Generated by Host
EUI64 ID Format NGUID ID Format ESXi 8.0
yes yes t10.xxx_EUI64
yes no t10.xxx_EUI64
no yes eui.xxx (NGUID) as primary ID

t10.xxx_controller_serial_number as alternative primary ID

Verify Mapping Between Primary and Alternative Device Identifiers

Use the esxcli storage core device uidmap list command to verify the device identifiers. The output is similar to the following: 
 esxcli storage core device uidmap list
eui.0000xyz.....
   Primary UID: eui.0000xyz.....
   Alternative Primary UIDs: t10.0000abc....
   Legacy UID: vml.0000000000766d68....
   Alternative Legacy UIDs: vml.000000000080906....

Rename Storage Devices

The ESXi host assigns a display name to a storage device based on the storage type and manufacturer. You can change the display name of the device.

You cannot rename certain types of local devices.

Procedure

  1. In the vSphere Client, navigate to the ESXi host.
  2. Click the Configure tab.
  3. Under Storage, click Storage Devices.
  4. Select the device to rename and click Rename.
  5. Change the device name to a friendly name.