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These enclosures do not support the following storage devices:
Tape drives
CD-ROMs
Solid state drives
The enclosure has guides that ensure the drives, EMU, I/O module, and power supplies
(the enclosure elements) align and properly mate with the backplane connectors. A
blower guide post on the blower ensures that the blower properly mates with the power
supply. The elements and the metal enclosure provide electromagnetic interference
(EMI) suppression and control air flow within the enclosure.
SCSI Buses
The enclosure supports only Wide-Ultra2 SCSI, wide (16-bit), internal LVD buses.
Depending on the host interface, the external SCSI bus, the bus from the I/O module to the
host can be either Wide-Ultra or Wide-Ultra2, LVD or SE. The SCSI bus type determines
the length of this bus, and therefore, the maximum cable length. The standard Compaq
cable length of 12 ft (3.7 m) ensures satisfactory operation. As for all SCSI buses, the
shorter the cable, the more efficient the bus operation.
NOTE: The maximum bus length is the inverse of the transmission speed. The faster the
transmission rate, the shorter the bus length. For more information about the supported SCSI
bus lengths, see Chapter 3.
Each enclosure has two internal SCSI buses, with half of the devices on each bus. The
single-bus I/O module places all the devices on a single-bus of either 10 or 14 devices. The
dual-bus I/O module maintains two internal buses with either 5 or 7 devices on each bus.
High Availability
The high availability features of the enclosure are a function of the blowers and the power
supplies.
Variable Speed Blowers
All enclosures have two variable speed blowers. In all configurations, the failure of one
blower automatically causes the other blower to operate at a high speed. This ensures that
the failure of a single blower does not disable the enclosure.
Introducing the Enclosure
1–3
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