Cheetah X15 Installation Guide
ST318451LW/LC and ST39251LC
SCSI interface disc drives
Publication Number: 83329485, Rev. B, September 2000
Handling precautions/Electrostatic discharge protection
• Disc drives are fragile. Do not drop or jar the drive and handle the drive
only by the edges or frame.
• Drive electronics are extremely sensitive to static electricity. Keep the
drive in its antistatic container until you are ready to install it. Wear a wrist
strap and cable connected to ground. Discharge static from all items near
or that will contact the drive. Never use an ohmmeter on any circuit
boards.
• Turn off the power to the host system during installation.
• Always use forced-air ventilation when operating the drive.
• Use caution when troubleshooting a unit that has voltages present.
• Do not disassemble the drive; doing so voids the warranty.
• Return the entire drive for depot service if any part is defective.
• Do not apply pressure or attach labels to circuit board or drive top.
Electromagnetic compliance
See Safety and Regulatory Agency Specifications, p/n 75789512.
Drive characteristics
ST318451
Formatted capacity .................................... 18.35 Gbytes
Max. data blocks ....................................... 35,843,670 (0222EE56h)
Cylinders and heads (user accessible) ...... 10,377 / 10 heads
Disc rotation ............................................... 15k rpm
Operating voltages
+5V
+12V
Typical operating current ......................... 0.8A
1.03A
ST39251
Formatted capacity .................................... 9.2 Gbytes
Max. data blocks ....................................... 17,921,835 (0111772Bh)
Cylinders and heads (user accessible) ...... 10,377 / 5 heads
Disc rotation ............................................... 15k rpm
Operating voltages
+5V
+12V
Typical operating current ......................... 0.79A
0.93A
What you need
• Phillips screwdriver and four 6-32 UNC drive mounting screws
• Forced-air ventilation to provide adequate drive cooling
• An unused drive power connector (not applicable to LC models)
To operate at LVD transfer rates, you may also need an LVD-capable SCSI
host adapter, LVD I/O cable and active negation external terminator
Multimode interface
This drive can operate in single-ended (SE) or low voltage differential (LVD)
mode. This multimode capability provides backwards compatibility so you
can use it with or without an LVD-capable host adapter. The primary bene-
fits of LVD technology include faster transfer rates, reduced power con-
sumption, increased allowable cable lengths, and improved device
connectivity.
You can configure the drive to switch between SE and LVD modes automat-
ically or force it to operate in SE mode only. To configure this option, see
Figure 2.
Note. To operate at the Ultra2 rates in LVD mode, all devices on the same
bus (cable) must be running in LVD mode. If you add any SE device
to the bus, all devices on that bus operate in SE mode.
Note. Some LVD host adapters provide an LVD connector and an SE con-
nector on the same host adapter to allow you to run SE and LVD
drives concurrently at their maximum capabilities. Check your SCSI
host adapter documentation. See Figure 3.
Caution. Do not mix LVD drives on the same bus with high voltage differen-
tial (HVD) devices–drive damage may occur.
Installation instructions
1.
Set the SCSI ID
Determine which SCSI IDs are already being used in the system and then
assign this disc drive a SCSI ID that isn’t already being used. Use the J6
connector located on the front of the drive to set the SCSI ID (see Figure 1).
• Most Cheetah X15 drives are factory set with the SCSI ID set at 0. If this
is the only SCSI drive in your system and there are no other SCSI
devices on the daisychain, you can leave this drive’s SCSI ID set to 0 and
proceed to the next step.
• The host system’s SCSI controller usually uses SCSI ID 7.
• If you have an LC model drive, the host normally sets the ID over the I/O
interface, so you don’t need to worry about this step.
• Some systems provide a cable designed to connect to the J5 jumper
block on the drive to remotely set the ID. You can connect this cable to J5
and use the host-provided remote switch to set the SCSI ID.
Figure 1.
Setting the SCSI ID
2.
Configure termination
If you are installing the drive in a system that has other SCSI devices
installed, terminate only the end devices on the SCSI bus (cable). This drive
does not have internal terminators or any other way of adding internal termi-
nation on the drive. You must provide external termination when termination
is required. This is normally done by adding an inline terminator on the end
of the cable. See Figure 3 for an illustration showing a system configuration
that uses a external terminator.
• Use active (ANSI SCSI-2 Alternative 2) single-ended terminators when
terminating a bus operating in single-ended mode.
• Use SPI-2-compliant active low voltage differential terminators when ter-
minating a SCSI Ultra2 bus operating in LVD mode.
• The host adapter is normally on the end of the bus and internally termi-
nated. You can configure your bus with another device on the end if you
remove termination from the host adapter.
3.
Configure terminator power
Terminators have to get power from some source. The default configuration
results in the drive not supplying termination power to the bus. You should
normally leave this drive set at this default unless your host system requires
the drive to supply termination power to the bus. To configure this drive to
supply termination power to the bus, place a jumper on J2 pins 1 and 2 as
shown in Figure 2.
• Host systems designed to use LC drives normally provide termination
power from the host adapter or other source. For this reason, LC model
drives cannot be configured to provide termination power to the bus.
SCSI ID = 0
(default)
Jumper Plug
(enlarged to
show detail)
J6
Drive
Front
Pin 1
Reserved
A
2
A
1
A
0
A
L
E
D
R
E
S
3
SCSI ID = 1
SCSI ID = 2
SCSI ID = 3
SCSI ID = 4
SCSI ID = 5
SCSI ID = 6
SCSI ID = 7
SCSI ID = 8
SCSI ID = 9
SCSI ID = 10
SCSI ID = 11
SCSI ID = 12
SCSI ID = 13
SCSI ID = 14
SCSI ID = 15
J1
DC Power
J1
68 Pin
SCSI I/O
Connector
Drive HDA
Rear
SCSI ID = 8
SCSI ID = 9
SCSI ID = 10
SCSI ID = 11
SCSI ID = 12
SCSI ID = 13
SCSI ID = 14
SCSI ID = 15
A
not used
3 A2 A1
SCSI ID = 0
SCSI ID = 1
SCSI ID = 2
SCSI ID = 3
SCSI ID = 4
SCSI ID = 5
SCSI ID = 6
SCSI ID = 7
A0
J5
Pin 1
4P
3P 2P
1P
PCBA
Pin 1
+5V
Ground
(default)
