Compaq StorageWorks 4000 - RAID Array Technology Brief page 13

Compaq RAID Array 4000 Overview
Figure 7 shows that the Storage Hub 7 contains seven serially connected ports. The Storage
Hub 12, on the other hand, contains 12 serially connected ports. Internal signaling within the hubs
is electrical. The internal hub connections and logic create an FC-AL. The bandwidth of the loop
is shared by all ports on the loop. A single pair of ports on the loop communicates at any one
time, while the other ports on the loop act as repeaters. Each port is fitted with a port bypass
switch to maintain the continuity of the loop in the event a controller or device attached to that
port malfunctions or is powered off. This port bypass capability improves fault tolerance.
Figure 7. Compaq StorageWorks Fibre Channel Storage Hub 7
The shortwave laser technology used in the RA4000 supports transmission distances between
components of up to 500 meters on 50-micron, multi-mode fiber optic cable with no
electromagnetic interference. Consequently, the Fibre Channel Host Adapter can be located as
much as 500 meters from the Fibre Channel Storage Hub, which in turn can be located as much
as 500 meters from the RA4000s. GBIC-LW and single-mode fiber optic cables increase the
point-to-point connection distance to 10 kilometers.
Figure 8. Possible storage configurations
ECG0205699A
GBIC-LW
< 10 km
Server
GBIC-SW
< 500 m
GBIC-LW
< 10 km
Hub
GBIC-SW
< 500 m
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Array