DWZZH 16–Bit UltraSCSI Hub (Rack-Mountable)
2–4
EK–SMDZS–UG. B01
2.2
Configuration Note
According to the UltraSCSI Configuration Guidelines (included in your
purchase), the maximum allowable cable distance for an UltraSCSI Domain is 74
meters. Each element, including the DWZZH-09 has an associated relative cable
distance value associated. Cables count as their specified distance, (including the
0.5 meter jumper cable between the SBB Hubs); but each DWZZH SBB counts
as an 18.5 meter cable equivalent. This means that communications from a
server attached to the left-hand SBB to a server attached to the right-hand SBB,
already has a 37.5 meter cable equivalent distance cost to propagate the signal
through the DWZZH-09 Hub. Therefore, if the distance from server A to the Hub
is X, and the distance from server B to the Hub is Y, then the sum cable distance
of X and Y must be less than or equal to 36.5 meters (74 – 37.5). Please note that
any SCSI transaction from a host to the storage subsystem only propagates
through one of the SBBs. This means that you may still have a cable length of 25
meters between the storage subsystem and the DS-DWZZH-09. Refer to Figure
2–4.
Figure 2–4 Maximum Allowable Cable Distances
