vsphere-esxi-vcenter-server-55-storage-guide

vSphere StoragePorts in Fibre Channel SANIn 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 identified in a number of ways.WWPN (World Wide PortName)Port_ID (or portaddress)A globally unique identifier for a port that allows certain applications toaccess the port. The FC switches discover the WWPN of a device or host andassign a port address to the device.Within a SAN, each port has a unique port ID that serves as the FC addressfor the port. This unique ID enables routing of data through the SAN to thatport. 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 byusing several WWPNs. This method allows an N-port to claim multiple fabric addresses, each of whichappears as a unique entity. When ESXi hosts use a SAN, these multiple, unique identifiers allow theassignment of WWNs to individual virtual machines as part of their configuration.Fibre Channel Storage Array TypesESXi supports different storage systems and arrays.The types of storage that your host supports include active-active, active-passive, and ALUA-compliant.Active-active storagesystemActive-passive storagesystemAsymmetrical storagesystemAllows access to the LUNs simultaneously through all the storage ports thatare available without significant performance degradation. All the paths areactive at all times, unless a path fails.A system in which one storage processor is actively providing access to agiven LUN. The other processors act as backup for the LUN and can beactively providing access to other LUN I/O. I/O can be successfully sent onlyto an active port for a given LUN. If access through the active storage portfails, one of the passive storage processors can be activated by the serversaccessing it.Supports Asymmetric Logical Unit Access (ALUA). ALUA-complaintstorage systems provide different levels of access per port. ALUA allowshosts to determine the states of target ports and prioritize paths. The hostuses some of the active paths as primary while others as secondary.Using Zoning with Fibre Channel SANsZoning provides access control in the SAN topology. Zoning defines which HBAs can connect to whichtargets. When you configure a SAN by using zoning, the devices outside a zone are not visible to the devicesinside the zone.Zoning has the following effects:• Reduces the number of targets and LUNs presented to a host.• Controls and isolates paths in a fabric.• Can prevent non-ESXi systems from accessing a particular storage system, and from possiblydestroying VMFS data.• Can be used to separate different environments, for example, a test from a production environment.36 VMware, Inc.