6.0.1

Ports in Fibre Channel SAN
In the context of this document, a port is the connection from a device into the SAN. Each node in the SAN,
such as a host, a storage device, or a fabric component has one or more ports that connect it to the SAN.
Ports are identied in a number of ways.
WWPN (World Wide Port
Name)
A globally unique identier for a port that allows certain applications to
access the port. The FC switches discover the WWPN of a device or host and
assign a port address to the device.
Port_ID (or port
address)
Within a SAN, each port has a unique port ID that serves as the FC address
for the port. This unique ID enables routing of data through the SAN to that
port. The FC switches assign the port ID when the device logs in to the fabric.
The port ID is valid only while the device is logged on.
When N-Port ID Virtualization (NPIV) is used, a single FC HBA port (N-port) can register with the fabric by
using several WWPNs. This method allows an N-port to claim multiple fabric addresses, each of which
appears as a unique entity. When ESXi hosts use a SAN, these multiple, unique identiers allow the
assignment of WWNs to individual virtual machines as part of their conguration.
Fibre Channel Storage Array Types
ESXi supports dierent storage systems and arrays.
The types of storage that your host supports include active-active, active-passive, and ALUA-compliant.
Active-active storage
system
Allows access to the LUNs simultaneously through all the storage ports that
are available without signicant performance degradation. All the paths are
active at all times, unless a path fails.
Active-passive storage
system
A system in which one storage processor is actively providing access to a
given LUN. The other processors act as backup for the LUN and can be
actively providing access to other LUN I/O. I/O can be successfully sent only
to an active port for a given LUN. If access through the active storage port
fails, one of the passive storage processors can be activated by the servers
accessing it.
Asymmetrical storage
system
Supports Asymmetric Logical Unit Access (ALUA). ALUA-complaint
storage systems provide dierent levels of access per port. ALUA allows
hosts to determine the states of target ports and prioritize paths. The host
uses some of the active paths as primary while others as secondary.
Using Zoning with Fibre Channel SANs
Zoning provides access control in the SAN topology. Zoning denes which HBAs can connect to which
targets. When you congure a SAN by using zoning, the devices outside a zone are not visible to the devices
inside the zone.
Zoning has the following eects:
n
Reduces the number of targets and LUNs presented to a host.
n
Controls and isolates paths in a fabric.
n
Can prevent non-ESXi systems from accessing a particular storage system, and from possibly
destroying VMFS data.
n
Can be used to separate dierent environments, for example, a test from a production environment.
vSphere Storage
36 VMware, Inc.