6.7

Table Of Contents
Figure 25. Target and LUN Representations
Storage Array
Target
LUN LUN LUN
Storage Array
Target TargetTarget
LUN LUN LUN
In this illustration, three LUNs are available in each configuration. In one case, the host connects to one
target, but that target has three LUNs that can be used. Each LUN represents an individual storage
volume. In the other example, the host detects three different targets, each having one LUN.
Targets that are accessed through the network have unique names that are provided by the storage
systems. The iSCSI targets use iSCSI names. Fibre Channel targets use World Wide Names (WWNs).
Note ESXi does not support accessing the same LUN through different transport protocols, such as
iSCSI and Fibre Channel.
A device, or LUN, is identified by its UUID name. If a LUN is shared by multiple hosts, it must be
presented to all hosts with the same UUID.
How Virtual Machines Access Storage
When a virtual machine communicates with its virtual disk stored on a datastore, it issues SCSI
commands. Because datastores can exist on various types of physical storage, these commands are
encapsulated into other forms, depending on the protocol that the ESXi host uses to connect to a storage
device.
ESXi supports Fibre Channel (FC), Internet SCSI (iSCSI), Fibre Channel over Ethernet (FCoE), and NFS
protocols. Regardless of the type of storage device your host uses, the virtual disk always appears to the
virtual machine as a mounted SCSI device. The virtual disk hides a physical storage layer from the virtual
machine’s operating system. This allows you to run operating systems that are not certified for specific
storage equipment, such as SAN, inside the virtual machine.
The following graphic depicts five virtual machines using different types of storage to illustrate the
differences between each type.
vSphere Storage
VMware, Inc. 19