HP StorageWorks Ultrium Full-Height SCSI Tape Drives User Guide (EH853-90905, August 2007)

With external devices
The cable provid
ed with all HP StorageWorks Ultrium external tape drives will attach to a computer with
a wide, very high densit y (VHD), LVDS SCSI connector.
If your server or host bus adapter is equipped with a high density (HD) wide SCSI connector, you will need
to order a 68-pin VHD-to-HD converter or 68-pin VHD-to-HD cable. See h
ttp://www.hp.com/go/connect.
With removable devices
For HP StorageWorks Ultrium removable tape drives, appropriate cables and terminators are provided
with the tape array.
Note on SE an d LVD interfaces
SE and LVD define how the signals are transmitted along the cable.
• With single-
ended (SE) SCSI, each signal travels over a single wire and each signal’s value is
determined by comparing the signal to a paired ground wire. Signal quality tends to decrease
over longer cab le lengths or at increased signal speed.
• With low volt
age differential (LVD) signaling, signals travel along two wires and the difference in
voltage bet
ween the wire p airs determines the signal value. This enables faster data rates and
longer cabling with less susceptibility to noise than SE signaling and reduced power consumption.
If you use LVD SCSI devices on the same bus as single-ended devices this will switch the LVD SCSI host
adapter into single-ended mode and restrict cable length.
If you connect only LVD SCSI devices, the bus will operate in low voltage differential mode and Ultra160
and higher speeds will be enabled. If you use a combination of Ultra160 and Ultra2 devices, each
device wil
l o perate at its optimum speed.
Ultrium full-height SCSI Tape D rives
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