May 30, 2015

vSphere Storage Terminologies - Identifiers

Identifiers

The following are definitions for some LUN identifiers and their conventions:
naa.<NAA>:<Partition>
eui.<EUI>:<Partition>

NAA or EUI

NAA stands for Network Addressing Authority identifier.
EUI stands for Extended Unique Identifier.

The number is guaranteed to be unique to that LUN. The NAA or EUI identifier is the preferred method of identifying LUNs and the number is generated by the storage device. Since the NAA or EUI is unique to the LUN, if the LUN is presented the same way across all ESXi hosts, the NAA or EUI identifier remains the same.

The <Partition> represents the partition number on the LUN or Disk. If the <Partition> is specified as 0, it identifies the entire disk instead of only one partition. This identifier is generally used for operations with utilities such as vmkfstools.

Example:
naa.6090a038f0cd4e5bdaa8248e6856d4fe:3 = Partition 3 of LUN naa.6090a038f0cd4e5bdaa8248e6856d4fe.

MPX

mpx.vmhba<Adapter>:C<Channel>:T<Target>:L<LUN> or mpx.vmhba<Adapter>:C<Channel>:T<Target>:L<LUN>:<Partition>

Some devices do not provide the NAA number described above. In these circumstances, an MPX Identifier is generated by ESXi to represent the LUN or disk. The identifier takes the form similar to that of the canonical name of previous versions of ESXi with the mpx. prefix. This identifier can be used in the exact same way as the NAA Identifier described above.

vml.<VML> or vml.<VML>:<Partition>

The VML Identifier can be used interchangeably with the NAA Identifier and the MPX Identifier. Appending :<Partition> works in the same way described above. This identifier is generally used for operations with utilities such as vmkfstools.
vmhba<Adapter>:C<Channel>:T<Target>:L<LUN>

This identifier is now used exclusively to identify a path to the LUN. When ESXi detects that paths associated to one LUN, each path is assigned this Path Identifier. The LUN also inherits the same name as the first path, but it is now used an a Runtime Name, and not used as readily as the above mentioned identifiers as it may be different depending on the host you are using. This identifier is generally used for operations with utilities such as vmkfstools.

Example: vmhba1:C0:T0:L0 = Adapter 1, Channel 0, Target 0, and LUN 0.

Note: Generally, multi-port fiber channel adapters are equipped with dedicated controllers for each connection, and therefore each controller is represented by different vmhba#. If the adapter supports multiple connections to the same controller, it is represented by a different channel number. This representation is directly dependent on the capability of the adapter.

<UUID>

The <UUID> is a unique number assigned to a VMFS volume upon the creation of the volume. It may be included in syntax where you need to specify the full path of specific files on a datastore.

"UUID - A unique number assigned to a VMFS volume upon the creation of the volume. The UUID is generated on the initial ESXi host that created the VMFS volume.”
       /commands/localcli_storage-vmfs-extent-list.txt from vmsupport


Volume Name
VMFS UUID Extent Number Device Name Partition
View Replica Disks 4eb2c729-33e3f6aa-4888-001b213752b8 0 naa.6000d3100033e6000000000000000013 1

"mpx.vmhba - Some devices do not provide NAA IDs. VMware assigns an MPX identifier to local devices to represent CD ROMs, disks, SW iSCSI disks, and USBs."

"vmhba - Identifies a path to a LUN. This is a runtime name assigned by vmkernel to the storage adapter path to the LUN."

Example:
vmhba1:C0:T0:L0 = Adapter 1, Channel 0, Target 0, and LUN 0
The above terms are unique identification numbers assigned to LUNs by operating systems, storage controllers, or storage devices.

Reference:

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