Hot plug/unplug support
The drives do support Hot Plug/Unplug
-refer to Ultrastar 9LP & 18XP
Hardware/ Functional Specification for
more details. Hot plugging the SCSI
bus may cause glitches on the bus. To
minimise the chance of glitching, it is
recommended to plug in the SCSI bus
before the power is applied.
During hot plugging, the supplies must
not go over the upper voltage limits.
This means that proper ESD protection
must be used during the plugging
event. Care must be taken not to
exceed
shock
limits
whilst hotpluging or
unplugging.
50 Pin SCSI Signal Connector
50 pin models use an AMP PN 84412-1
connector. The connector is compatible
with the ANSI SCSI ‘A’ connector
specifications. It is limited to 8 bit data
transfers only.
Notes:
“SEF” stands for Single Ended Fast
“SEFW” stands for Single Ended Fast
Wide
“DFW” stands for Differential Fast Wide
50 pin SCSI connector models offer an
8 bit SCSI bus using the SCSI “A”
connector.
68 pin SCSI connector model offers an
8/16 bit SCSI bus using the SCSI “P”
connector which supports Wide data
transfers.
80 pin SCSI connector models offer an
8/16 bit SCSI bus using the SCA
connector.
All models support Fast SCSI data
transfers and the U, X and Y models
also support SCSI-3 FAST 20 data
transfer.
68 Pin SCSI Signal Connector
68 pin models use an MOLEX
connector (PN 87360-0001) that is
compatible with the ANSI SCSI “P”
connector specifications. It can transfer
data in both 8 bit (narrow) and 16 bit
(wide) modes. Both single-ended and
differential versions are supported. The
differential 68 pin models are
electrically compatible with differential
50 pin models and other 50 pin
differential SCSI products and therefore
can coexist on the same bus. In order
to do so, the differences in connector
types would need to be accounted for in
the cable. Connecting 68 and 50 pin
single-ended models to the same bus
can also coexist. Differential and
single-ended models do not work
connected to the same bus.
80 Pin (Single Connector
Attachment)
80 pin SCA-2 models use an AMP
connector (PN 5-917593-9) that is
compatible with the specification of:
‘Single Connector Attachment for Small
SCSI Disk Drives’ SFF 8046. It can
transfer data in both 8 bit (Narrow) and
16 bit (wide) modes.
Note: The “SCA-2” connector is not
mechanically compatible with the
50 pin “A” connector or the 68 pin
“P” connector as defined in the
ANSI SCSI standard. This
connector is intended for direct
backplane attachment and is not
intended to be cable attached to
the bus.
SCSI Bus Cable
Single-ended models permit cable
lengths of up to 6 metres (19.68 feet). It
should be noted however that users
who plan to use ‘Fast’ data transfers
with single-ended models should follow
all of the ANSI SCSI guidelines for
single-ended ‘Fast’ operations. This
may
include a cable length of less than
6 metres.
SCSI 3 Fast 20 models can be cable
connected to a 3 metre (9.8 feet) cable
when a maximum of 4 devices are
attached, and a 1.5 metre (4.9 feet)
cable with up to 8 devices attached.
SCA-2 connector models are not
designed for direct
cable attachment
due to the combination of power and
SCSI bus signals. ‘Fast & Fast 20’ data
transfers with SCA models should
follow all of the ANSI SCSI guidelines.
Differential models permit cable lengths
of up to 25 metres (82.02 feet). Cables
must meet the requirements for
differential cables as set forth in the
ANSI SCSI standard under ‘Cable
Requirements -Differential Cable’.
The ANSI SCSI standard states that
any stub from main cable must not
exceed 0.1 metres for
single-ended
cables and 0.2 metres for differential
cables. Ultrastar 9LP & 18XP has a
maximum internal stub length of 0.05
metres on all ‘single-ended’ SCSI
signals, and 0.1 metres on all
‘differential’ SCSI signals. To remain
compliant with the standard the SCSI
bus cable must not add more than 0.05
metres additional stub length to any of
the single-ended SCSI signals or 0.10
metres to any differential SCSI signals.
Models
DGHS
Capacity GB
SCSI Pins/
SCSI Electrical
Model No.
(at 512 Byte)
Connector Type
Signal Type
09Z
9.11
50
SEF
09U
9.11
68
SEFW
09X
9.11
68
DFW
09Y
9.11
80 SCA-2
SEFW
18Z
18.22
50
SEF
18U
18.22
68
SEFW
18X
18.22
68
DFW
18Y
18.22
80 SCA-2
SEFW
