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SSA and Fibre Channel Myths and Realities

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SSA and Fibre Channel Myths and Realities (PDF)
A White Paper prepared by Greg Schulz of MTI, for the SCSI Trade Association

This paper reviews some myths about IBM® Serial Storage Architecture (SSA), Fibre Channel
(FC) and traditional Small Computer System Interface (SCSI) technologies. Some will argue that
parallel SCSI is at or near the end of its life cycle while SSA is a newly established architecture
with Fibre Channel still evolving. SSA and Fibre Channel, including Fibre Channel-Arbitrated
Loop (FC-AL), share many common characteristics:

  • Both are serial architectures sending a stream of bits over a communication path
  • Both use fiber optics to digitally transmit high-speed serial bit streams
  • Both support more devices over longer distances than parallel SCSI
  • Both are open standards although SSA is perceived as an IBM proprietary protocol
  • Both provide improved bandwidth compared to traditional parallel SCSI with FC being
  • faster

The following are some myths and realities involving SSA, Fibre Channel and parallel SCSI.
Similar to parallel SCSI, which evolved from SCSI-1 to SCSI-2 and now SCSI-3, Fibre Channel
is deliverable today while still evolving. SSA has also evolved into a stable product with limited
support from the industry.