
Chapter 2. Netfinity solutions 33
Unlike the ServeRAID or SSA adapters, this Fibre Channel adapter does not
control how the data is stored on the disks and how the disks are managed. The
adapter merely acts as a conduit. It is the RAID controller that controls all disk
operations, as described in 2.3.5, “Netfinity Fibre Channel RAID Controller Unit”
on page 36.
The maximum number of host adapters supported in Netfinity systems is limited
only by the number of available PCI slots.
2.3.2 Netfinity Fibre Channel Hub
The Netfinity Fibre Channel Hub (part 35231RU or SFCH1xx in EMEA where xx
is the country code) is a seven-port device. Much like in a traditional network, the
hub relays data signals from one port to another. Although not needed for simple
configurations, it is required for cluster and redundancy configurations and for
those requiring cable lengths greater than 500 meters. If necessary, two hubs can
be cascaded together for more complex configurations.
Figure 16. Netfinity Fibre Channel Hub
The hub supports both long-wave and short-wave fiber optic cabling. Short-wave
connections are used for connectivity to the host adapter and to the RAID
controller unit and can be up to 500 meters long. Long-wave cables are used for
connections between hubs and can be up to 10 km long.
Since each hub has seven ports, to build large configurations, the hubs can be
connected together as shown in Figure 17, so that up to a total of 37 ports can be
made available for attachment to host adapters or RAID controller units. However,
for optimum performance, it is recommended that no more than two RAID
controller units be attached to a single hub.
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