Proware EP-2243D-F4S3, User Manual

Page: 17 / 138

Fibre to SAS/SATA II RAID Subsystem
User Manual 17
Arbitrated Loop
The arbitrated loop (FC-AL) topology provides a relatively simple method of
connecting and sharing resources. This topology allows up to 126 devices or nodes
in a single, continuous loop or ring. The loop is constructed by daisy-chaining the
transmit and receive cables from one device to the next or by using a hub or
switch to create a virtual loop. The loop can be self-contained or incorporated as an
element in a larger network. Increasing the number of devices on the loop can
reduce the overall performance of the loop because the amount of time each device
can use the loop is reduced. The ports in an arbitrated loop are referred as L-Ports.
Switched Fabric
A switched fabric a term is used in a Fibre channel to describe the generic switching or
routing structure that delivers a frame to a destination based on the destination
address in the frame header. It can be used to connect up to 16 million nodes, each of
which is identified by a unique, world-wide name (WWN). In a switched fabric, each
data frame is transferred over a virtual point-to-point connection. There can be any
number of full-bandwidth transfers occurring through the switch. Devices do not have
to arbitrate for control of the network; each device can use the full available
bandwidth.
A fabric topology contains one or more switches connecting the ports in the FC
network. The benefit of this topology is that many devices (approximately 2-24) can
be connected. A port on a Fabric switch is called an F-Port (Fabric Port). Fabric
switches can function as an alias server, multi-cast server, broadcast server, quality
of service facilitator and directory server as well.
1.3.3 Basic Elements
The following elements are the connectivity of storages and Server components using
the Fibre channel technology.
Cables and connectors
There are different types of cables of varies lengths for use in a Fibre Channel
configuration. Two types of cables are supported: Copper and Optical (fiber).
Copper cables are used for short distances and transfer data up to 30 meters per link.
Fiber cables come in two distinct types: Multi-Mode fiber (MMF) for short
distances (up to 2km), and Single-Mode Fiber (SMF) for longer distances (up to
10 kilometers). B y d e f a u l t , t h e R A I D s u b s y s t e m supports two short-wave
multi-mode fibre optic SFP connectors.
Fibre Channel Adapter
Fibre Channel Adapter is a device that is connected to a workstation, server, or host
system and control the protocol for communications.
Hubs
Fibre Channel hubs are used to connect up to 126 nodes into a logical loop. All
connected nodes share the bandwidth of this one logical loop. Each port on a hub