6.5

Table Of Contents
Typically, the path to the device has the following format.
vmhba<adapter>:C<channel>:T<target>:L<LUN>
n
vmbh<adapter> is the name of the storage adapter. The name refers to the physical adapter on the
host, not the SCSI controller used by the virtual machines.
n
C<channel> 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
T<target> is the target number. Target numbering is determined by the host and might change if
the mappings of targets that are visible to the host change. Targets that are shared by dierent
hosts might not have the same target number.
n
L<LUN> is the LUN number that shows the position of the LUN within the target. The number is
provided by the storage system. If a target has only one LUN, the LUN number is always zero (0).
Legacy Identifiers
In addition to the SCSI INQUIRY or mpx identiers, ESXi generates an alternative legacy name, called VML
name, for each device. Use the device UID instead.
Examining LUNs
A LUN (Logical Unit Number) is an identier for a disk volume in a storage array target.
Target and Device Representation
In the ESXi context, the term target identies a single storage unit that a host can access. The terms device
and LUN describe a logical volume that represents storage space on a target.
The terms device and LUN mean a SCSI volume presented to the host from a storage target.
Dierent storage vendors present their storage systems to ESXi hosts in dierent ways. Some vendors
present a single target with multiple LUNs on it. Other vendors, especially iSCSI vendors, present multiple
targets with one LUN each.
Figure 43. Target and LUN Representations
storage array
target
LUN LUN LUN
storage array
target targettarget
LUN LUN LUN
In Figure 4-3, three LUNs are available in each conguration. On the left, the host sees one target, but that
target has three LUNs that can be used. Each LUN represents an individual storage volume. On the right,
the host sees three dierent targets, each having one LUN.
Chapter 4 Managing Storage
VMware, Inc. 45