6.7

Device Identifiers
Depending on the type of storage, the ESXi host uses different algorithms and conventions to generate
an identifier for each storage device.
SCSI INQUIRY
identifiers.
The host uses the SCSI INQUIRY command to query a storage device. The
host uses the resulting data, in particular the Page 83 information, to
generate a unique identifier. Device identifiers that are based on Page 83
are unique across all hosts, persistent, and have one of the following
formats:
n
naa.number
n
t10.number
n
eui.number
These formats follow the T10 committee standards. See the SCSI-3
documentation on the T10 committee website.
Path-based identifier. When the device does not provide the Page 83 information, 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 SCSI INQUIRY identifies.
The mpx. 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
n
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.
n
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.
n
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.
vSphere Storage
VMware, Inc. 130