Computer Drive User Manual

12 Barracuda 50 Installation Guide, Rev. A
Data bus widths
These drives have a wide (16-bit) SCSI data bus. You can use
these drives on a non-wide (8-bit) data bus if you provide proper
termination to the upper eight data lines. This is often referred to
as providing “high-9 termination” (the other bit is for parity).
The following table lists the maximum cable lengths and number
of devices using single-ended and LVD I/O circuits.
Providing adequate cooling
The enclosure design must ensure adequate cooling for the
drive. The maximum ambient temperature allowed is 50°C.
The drive’s product manual (83329471) describes how to evalu-
ate the air-flow design. The evaluation consists of ensuring that
the case temperature of certain critical components remains
within acceptable limits during drive operation.
Figure 2 shows two design approaches with one or more fans
used to generate air flow. The air-flow patterns can be created
Table 1. SE and LVD bus configurations
SCSI
driver
type
I/O transfer rate
(Mbytes/s)
Maximum
number of
devices on
bus
Maximum cable
length allowed
SE 20 16 6 meters (19.7 ft.)
SE 40 4 3 meters (9.8 ft.)
SE 40 8 1.5 meters (4.9 ft.)
LVD 80 16 12 meters (39.4 ft.)