Newsgroup: it.comp.hardware.scsi
Titolo: Chi mispega : SCSI-1,2,3 / FAST/ ULTRA / WIDE ...

Come da titilo : qualcuno č cosě gentile da spegarmi la differenza o
da indicarmi qualche fonte di informazioni ?
Grazie.

Grazie.
Allora, 
(da Implementing ServeRAID SCSI and SSA RAID Disk
 Subsystems)
SCSI-I
   SCSI is a standard defined by the American National Standards
Institute 
   (ANSI).  The original SCSI standard is defined in ANSI standard 
   X3.131-1986.  It defines an 8-bit interface with a burst-transfer
rate of 
   5 MBps with a 5 MHz clock (1 byte transferred per clock cycle). 
   It is sometimes referred to as SCSI-I to differentiate it from the
generic 
   term SCSI.  SCSI-I was the first of all SCSI technologies to come
about 
   and was the fastest controller interface at the time. 
SCSI-II
   The SCSI-II specification gained final approval from ANSI in 1994
as 
   standard X3T9.2/375R Revision 10K.  SCSI-II allowed for better
performance 
   than SCSI-I.  It defines extensions to SCSI that allow for 16- and
32-bit 
   devices, a 10 MBps synchronous transfer rate for 8-bit transfers
and 20 
   MBps for 16-bit transfers, and other enhancements discussed below. 
   SCSI-II comes in many varieties: SCSI-II,  SCSI-II Fast, SCSI-II
Fast Wide 
   and Ultra SCSI (Fast-20 Wide). 
   The interface for SCSI-II also defined additional control signals
as well 
   as additional data signals.  This meant that the maximum number of
devices 
   supported by one SCSI channel was increased from 8 to 16. 
SCSI-III
   ANSI continues to develop the SCSI-II specification, to address
issues of 
   cable definition, termination, confusing SCSI-II commands and
electrical 
   and signal timing definitions.  The SCSI-III architecture
encompasses 
   protocols, commands and interconnects: 
   °   The SCSI-III command set consists of five command sets that are
       derived from SCSI-II command sets and a new SCSI-III command
set for 
       RAID controllers. 
   °   The interconnect technologies for SCSI-III specifications are: 
       -   Fiber Channel Physical and Signaling Interface 
       -   IEEE 1394 High Performance Serial Bus ("FireWire") 
       -   SCSI-III Parallel Interface 
       -   Serial Storage Architecture Bus 
   °   The SCSI-III protocol standards are: 
       -   SCSI-III Interlock Protocol 
       -   SCSI-III Serial Storage Protocol 
       -   SCSI-III Serial Bus Protocol 
       -   Fiber Channel Protocol for SCSI 
   Currently SCSI-III has a transfer rate of 40 MBps and includes
Fast-20 
   Narrow and Fast-20 Wide. 
   SCSI-III will be a great step forward in the development of disk 
   subsystems.  SCSI-III will further enhance the SCSI-II interface in
the 
   following ways: 
   °   SCSI-III provides three new physical interface layers, SSA, FC
and 
       FireWire. These new layers provide better performance, higher 
       availability and more expandability to SCSI. 
   °   SCSI-III is broken down into more than 15 standards, each
dealing with 
       a separate part. Because SCSI had become a very large standard,
the 
       separation makes the SCSI standard easier to maintain and
better to 
       work with. It also allows parts of SCSI-III to be formalized
much 
       sooner. 
 The term Ultra SCSI is also another name for Fast-20 Wide.  Ultra
SCSI is 
   not equivalent to SCSI-III but rather a subset of the SCSI-III
Parallel 
   Interface (SPI). 
Per ulteriori info 
www.redbooks.ibm.com
 (inserire scsi come parola di
ricerca)