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Data Express Repeater Board Benefits
SCSI LVD Applications
StorCase Data Express removable SCSI drive enclosures are purchased and installed
into a variety of SCSI environments. Typically, these implementations
contain one or more unknown components that often vary from system to
system, such as the internal or external SCSI cable lengths, manufacturers
and/or connector types; the specific terminator types and/or spacing; the
SCSI device spacing; and/or the type of controller(s).
Specifically in LVD/single-ended implementations, these unknown system components and their combinations
may produce impedance mismatches, excessive capacitance loading and/or noise interference within the system, potentially introducing intermittent
incompatibility issues.
To minimize these unpredictable
effects caused by varying system specifications, StorCase strongly
recommends the installation of the Data Express Repeater/Isolator
Board on ALL Data Express Ultra2 and Ultra160 receiving frames
(Ultra320 models are currently only available with this Repeater/Isolator
Board pre-integrated onto their receiving frame; for Ultra320,
it is not offered as a separate option). The Repeater/Isolator
Board provides a signal repeater function that allows the Data
Express drive enclosure to contribute to improved signal quality
to and from the drive.
The following test results are provided to demonstrate the improvement in drive signal quality that results when a
Data Express with an installed Repeater/Isolator Board is introduced into a SCSI Ultra160 implementation in which all system components may
not
all necessarily conform completely to the Ultra160 specification.
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SCSI Ultra160 Configuration Using Controller A:
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All Components Conform to
Ultra160 Specification;
NO Data Express Installed.
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All Components Do NOT Conform to Ultra160 Specification;
NO Data Express Installed.
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All Components Do NOT Necessarily Conform to Ultra160 Specification;
Data Express DE100 w/Repeater Installed.
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| SCSI Ultra160 Configuration Using Controller B:
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All Components Conform to
Ultra160 Specification;
NO Data Express Installed.
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All Components Do NOT Necessarily Conform to Ultra160 Specification;
NO Data Express Installed.
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All Components Do NOT Necessarily Conform to Ultra160 Specification;
Data Express DE100 w/Repeater Installed.
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As shown, these results
support the StorCase recommendation to install the Repeater/Isolator
Board on all Data Express Ultra2 and Ultra160 receiving frames.
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