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SCSI Standards:

Switch Configuration:

Built to Order?

Communication Mode:

Data Transfer Rate:

Product Form Factor:

Control:

Redundant Power Supplies?

Extends SCSI Distance?

CE / FCC Certified?

Help with SCSI Switches specifications:

SCSI Standards
   SCSI Standards      See tables at the end of this help file for definitions of several features of SCSI standards.
   Your choices are...         
   SCSI-1       SCSI-1, the original SCSI, was standardized by ANSI in 1986.  It allows asynchronous data transfer rates of 1.5 MB/sec and synchronous transfer rates to a maximum of 5 MB/sec. It has an 8-bit SCSI port that uses Single-ended open-collector drivers. Uses a 50-pin connector. SCSI-1 is an obsolete standard after the development of SCSI-2. 
   Wide SCSI       This term is generally applied to Wide (16-bit) SCSI with a fast data transfer rate of up to 10 MBps. 
   Fast SCSI       Standard defined in SCSI-2.  Increases the maximum data rate from 5 MBps for Narrow (8-bit) SCSI to 10 MBps. 
   Wide Fast SCSI       This term is generally applied to Wide (16-bit) SCSI with a fast data transfer rate of up to 20 MBps. 
   Ultra SCSI       This is also known as Fast-20. It doubles the FAST SCSI data rate to up to 20 MBps for the 8-bit bus 
   Wide Ultra SCSI       Wide Ultra SCSI defines a maximum transfer data rate up to 40 MBps for the Wide (16-bit) SCSI. 
   SCSI-2       SCSI-2 has significant improvements over SCSI-1 including faster data transfer rates, better connectors, wider bus path, better reliability via synchronous negotiation and parity checking. SCSI-2 has a data transfer rate from 5 MB/sec to 10 MB/sec. This speed change is called Fast SCSI-2. Also, SCSI-2 provides the option to double the bus from 8 bits to 16 bits. This change is known as Wide SCSI. By combining the Fast SCSI-2 with the Wide SCSI bus a maximum data rate of 20 MB/sec can be achieved. 
   Ultra2 SCSI       This is also known as Fast-40.  It doubles the Ultra SCSI data rate to up to 40 MBps for the 8-bit bus. 
   Wide Ultra2 SCSI       Wide Ultra2 SCSI defines a maximum data rate of 80 MBps for the Wide (16-bit) SCSI.   
   SCSI-3       The SCSI-3 specification allows for faster transfer rate, more devices on a single chain (a maximum of 32), and also it incorporates serial connections in addition to the traditional parallel interconnect of SCSI-2. The serial interconnect of SCSI-3 incorporates three technologies: Serial Storage Architecture (SSA), Fibre Channel, and IEEE P1394. The serial transfer mode allows faster data rates, more devices per bus, simple connectors, and longer cables. 
   Ultra3 SCSI (Ultra160)       This is also known as Fast-80 or Ultra-160. It doubles the Ultra2 SCSI data rate to up to 160 MBps for the 16-bit bus. 
   Ultra320 SCSI       Defines a maximum data rate of 320 MBps for the Wide (16-bit) SCSI. 
   Ultra640 SCSI       Defines a maximum data rate of 640 MBps for the Wide (16-bit) SCSI. 
   Fibre Channel       A high-speed serial protocol for channels and networks that uses links of twisted-pair, coaxial cable or fiber optic cable. SCSI can use the Fibre Channel Arbitrary Loop (FC-AL) topology. 
   Serial SCSI (FireWire®)       A very fast bus standard that supports data transfer rates of up to 400 Mbps. FireWire is a registered trademark of Apple Computers, Inc.  The standards are defined in IEEE 1394. 
   Other       Other unlisted, specialized, or proprietary SCSI standards. 
   Search Logic:      All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches.
   Tables:         
   Bus Width      

Bus Width

Width      

Definition

Narrow

Narrow SCSI is the conventional SCSI specified in the original SCSI. The bus width is 8 bits.

Wide

Uses a data bus that is 16 bits wide. This doubling of the bus width respect to the Narrow SCSI comes at a higher cost, and it requires additional cabling and connectors.

         

 
   SCSI Type      

SCSI Type

Type      

Definition

SCSI-1

SCSI-1, the original SCSI, was standardized by ANSI in 1986. Allows asynchronous data transfer rates of 1.5 MB/sec and synchronous transfer rates to a maximum of 5 MB/sec. It has an 8-bit SCSI port that uses Single-ended open-collector drivers. Uses a 50-pin connector. SCSI-1 is an obsolete standard after the development of SCSI-2.

SCSI-2

SCSI-2 has significant improvements over SCSI-1 including faster data transfer rates, better connectors, wider bus path, better reliability via synchronous negotiation and parity checking. SCSI-2 has a data transfer rate from 5 MB/sec to 10 Mb/sec. This speed change is called Fast SCSI-2. Also, SCSI-2 provides the option to double the bus from 8 bits to 16 bits. This change is known as Wide SCSI. By combining the Fast SCSI-2 with the Wide SCSI bus a maximum data rate of 20 MB/sec can be achieved.

SCSI-3

The SCSI-3 specification allows for faster transfer rate, more devices on a single chain (a maximum of 32), and also it incorporates serial connections in addition to the traditional parallel interconnect of SCSI-2. The serial interconnect of SCSI-3 incorporates three technologies: Serial Storage Architecture (SSA), Fibre Channel, and IEEE P1394. The serial transfer mode allows faster data rates, more devices per bus, simple connectors, and longer cables.

          

 
   Bus Speed      

Bus Speed

Speed         

Definition

Regular

This is the default speed of the original specifications of SCSI-1. The regular bus speed is 5 MHz.

Fast

Fast SCSI increases the bus speed to 10 MHz. This doubling of the bus speed was defined in SCSI-2.

Ultra

Also known as Fast-20, it is specified in SCSI-3. The bus speed of Ultra SCSI is 20 MHz. Ultra SCSI buses have a maximum transfer rate of 20 MB/sec for Narrow SCSI, and 40 MB/sec for Wide SCSI.

    

 
   SCSI Standards     

SCSI Standards

 

 

 

Maximum Bus Lengths (meters)

Max Devices Supported

Protocol    

Max Speed (MBps)

Bus Width  (bits)

Single-ended

LVD  

HVD  

 

SCCI-1

5

8

6

--

--

8

Fast SCSI

10

8

3

--

25

8

Fast Wide SCSI

20

16

3

--

25

16

Ultra SCSI

20

8

1.5

--

25

8

Wide Ultra SCSI

40

16

3

--

--

8

Ultra2 SCSI

40

8

--

12

25

8

Wide Ultra2 SCSI

80

16

--

12

25

16

Ultra3 SCSI (Ultra 160)

160

16

--

12

--

16

Ultra 320

320

16

--

12

--

16

       

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Switch Configuration
   Switch Configuration:      Normally the configuration of a switch is specified, as b x c, where b is the number of independent SCSI host buses that the switch connects to, and c is the number of SCSI channels.
   Your choices are...         
   1 x 2       One host to 2 channels. 
   1 x 3       One host to 3 channels. 
   1 x 4       One host to 4 channels. 
   2 x 1       Two hosts to 1 channel. 
   2 x 2       Two hosts to 2 channels. 
   3 x 1       Three hosts to 1 channel. 
   3 x 2       Three hosts to 2 channels. 
   3 x 3       Three hosts to 3 channels. 
   4 x 1       Four hosts to 1 channel. 
   4 x 2       Four hosts to 2 channels. 
   4 x 3       Four hosts to 3 channels. 
   4 x 4       Four hosts to 4 channels. 
   5 x 4       Five hosts to 4 channels. 
   5 x 5       Five hosts to 5 channels. 
   6 x 4       Six hosts to 4 channels. 
   Other       Other unlisted, specialized, or proprietary configuration. 
   Search Logic:      All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches.
   Built to Order?       For nonstandard configurations, some companies will build switches order. 
   Search Logic:      "Required" and "Must Not Have" criteria limit returned matches as specified. Products with optional attributes will be returned for either choice.
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Communication
   Communication Mode:      Generally SCSI data can be transmitted synchronously or asynchronously. Asynchronous transfer is faster on short cables, while synchronous is faster on long cables.
   Your choices are...         
   Synchronous Transfer       A method of transferring data that does not require that the bus wait for a REQ-ACK handshake in order to deliver the next byte of data. The target is allowed to send certain number of REQ pulses without waiting for return ACK pulses. The number of REQ pulses that can be sent without waiting for an ACK is called the "offset." This method results in a better utilization of the bus bandwidth and produces a higher data rate than with asynchronous transfer. 
   Asynchronous Transfer       A method of transferring data where the bus must wait for a REQ-ACK handshake in order to deliver the next byte of data. 
   Synchronous / Asynchronous Transfer       The device can automatically detect the type of transfer mode that should be used between the initiator and the target. 
   Search Logic:      All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches.
   Data Transfer Rate:       The maximum data transfer rate (MB/sec) of the SCSI device. 
   Search Logic:      All matching products will have a value greater than or equal to the specified value.
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Product Form Factor
   Product Form Factor      The size, shape, and functional type of the SCSI product.
   Your choices are...         
   Stand-alone Unit       An independent unit connected to a system. 
   Board-level Unit       A computer board that is to be inserted in a carrier. 
   ASIC       Application Specific Integrated Circuit (ASIC) is a chip designed for a particular application. ASICs are manufactured by connecting existing circuits in new ways. 
   Rack Mount       A unit that can be mounted in a rack together with other units. 
   Other       Other unlisted, specialized, or proprietary configurations. 
   Search Logic:      All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches.
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Control
   Control:      Methods and devices used to control and manage the SCSI switch.
   Your choices are...         
   RS232 Serial Port       RS232 interface that allows remote interaction and control of the SCSI switch. 
   Panel Control (LCD, or other)       Front panel, normally menu-driven, used to control the SCSI switch. 
   LAN Support       Allows communication and control of the SCSI switch via TCP/IP. 
   Manual Control       An operator-driven selector (mechanical switch or push-button) to control the SCSI switch. 
   Other       Other unlisted, specialized, or proprietary configuration. 
   Search Logic:      All products with ANY of the selected attributes will be returned as matches. Leaving all boxes unchecked will not limit the search criteria for this question; products with all attribute options will be returned as matches.
   Redundant Power Supplies?       More than one power supply for security. 
   Search Logic:      "Required" and "Must Not Have" criteria limit returned matches as specified. Products with optional attributes will be returned for either choice.
   Extends SCSI Distance?       The device has the capability of extending the SCSI bus beyond the standard (5 meters for single ended signaling and 25 meters for differential signaling). 
   Search Logic:      "Required" and "Must Not Have" criteria limit returned matches as specified. Products with optional attributes will be returned for either choice.
   CE / FCC Certified?       The unit conforms with the American requirements of the Federal Communication Commission (FCC) and with the European CE Marking (Conformite Europeene or European Conformity) system, which is helpful for exports to the countries of the European Economic Area (EEA). 
   Search Logic:      "Required" and "Must Not Have" criteria limit returned matches as specified. Products with optional attributes will be returned for either choice.
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