From Video and Media Servers: Technology and Applications, Second Edition


Not long after SCSI-1 was first introduced, its drawbacks became evident. Soon the need for a more advanced interface became obvious and the industry began what would be a long cycle of drive interface advances. The second step in our SCSI overview takes a brief retrospect of SCSI-1 versus SCSI-2 differences, then moves directly into the development and technology of SCSI-3 the next generation in connectivity and addressability.

Bandwidth, data transfer performance, and the number of large blocks of data being transported are all considerations for improving SCSI performance. While desktop, multimedia and video applications continue to grow, the need for implementation of enhanced bus performance becomes crucial. As SCSI transfer rate performance has increased, more applications are brought to market and the success of media servers for multimedia, non-linear editing, and video applications has soared.

Industry tests conducted in 1995 were already showing substantial improvements by using the newer and faster SCSI system protocols, especially as the block or file size transfer rates increased. The expectation of a future SCSI-3, under construction as early as 1993, changed the general perception that SCSI, as a command set protocol, may continue for quite some time.

The Next Step in SCSI

The final acceptance of SCSI-2 came in 1994, when ANSI approved the X3.131-1994 standard. We recall that a major improvement from SCSI-1 to SCSI-2 was the inclusion of the Common Command Set (CCS). The final standard included some otherwise optional sections of SCSI-1, but now made them mandatory in SCSI-2.


Products & Services
SCSI Converters
SCSI converters translate between the various SCSI interfaces such as single-ended to high-voltage differential (HVD), or HVD to low-voltage differential (LVD), etc.
SCSI Cables
SCSI cables are used for high-speed bus connections between small computers and intelligent peripherals such as hard disks, printers, and optical disks.
SCSI Adapters and SCSI Controllers
SCSI adapters and SCSI controllers (SCSI cards) are computer interface cards that are installed in an expansion slot. They are used to connect the SCSI system to several devices and peripherals using a daisy chain method.
Bus Extenders
Bus extenders are used to increase cable lengths for distance-limited bus protocols.
SCSI Switches
SCSI switches connect test points or devices to instruments for the testing, measuring, or monitoring industrial systems. Small computer system interface (SCSI) is an intelligent peripheral bus with a standard, device-independent protocol that allows many peripheral devices to be connected to the SCSI port.

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