SCSI

SCSI (Small Computer System Interface) is a set of standards for physically connecting and transferring data between devices such as hard disk drives, tape drives, and CD-ROM drives from companies like IBM, Apple, and Compaq. Developed by the American National Standards Institute (ANSI) and the Institute of Electrical and Electronics Engineers (IEEE), SCSI has been widely used in Unix-based systems, Windows NT, and Mac OS from Apple Inc.. The development of SCSI was influenced by the work of Shugart Associates, NCR Corporation, and Adaptec, which were among the first companies to develop and implement the technology.

Introduction to SCSI

SCSI is a parallel interface that allows multiple devices to be connected to a single host adapter, such as those from Adaptec or LSI Logic, using a daisy chain topology. This allows for the connection of up to 16 devices, including hard disk drives from Western Digital and Seagate Technology, tape drives from Quantum Corporation, and CD-ROM drives from Sony and Toshiba. The SCSI interface is commonly used in data centers and server farms from companies like Google, Amazon, and Microsoft, where high-performance storage is required. The use of SCSI has also been seen in mainframe computers from IBM and Unisys, as well as in supercomputers from Cray Inc. and Hewlett Packard Enterprise.

History of SCSI

The development of SCSI began in the early 1980s, with the first standard, SCSI-1, being published in 1986 by the American National Standards Institute (ANSI). This was followed by the development of SCSI-2 in 1994, which increased the speed and capacity of the interface. The SCSI Trade Association (STA) was formed in 1996 to promote the use of SCSI and to develop new standards, such as SCSI-3 and Ultra320. The work of the STA has been supported by companies like Intel, Dell, and Hewlett Packard, which have developed and implemented SCSI technology in their products. The development of SCSI has also been influenced by the work of IEEE and the International Electrotechnical Commission (IEC), which have developed standards for the interface.

SCSI Architecture

The SCSI architecture is based on a master-slave relationship between the host adapter and the devices connected to it. The host adapter, such as those from LSI Logic or Adaptec, acts as the master, while the devices, such as hard disk drives from Western Digital and Seagate Technology, act as slaves. The SCSI interface uses a parallel bus to transfer data between the host adapter and the devices, with the bus width and bus speed determining the overall performance of the interface. The use of SCSI has been seen in storage area networks (SANs) from companies like EMC Corporation and NetApp, as well as in network-attached storage (NAS) devices from Synology and Qnap.

SCSI Interfaces

There are several types of SCSI interfaces, including Parallel SCSI, Serial SCSI, and iSCSI. Parallel SCSI is the original interface, which uses a parallel bus to transfer data. Serial SCSI is a newer interface, which uses a serial bus to transfer data and is faster and more reliable than parallel SCSI. iSCSI is a protocol that allows SCSI devices to be connected over a TCP/IP network, such as those from Cisco Systems and Juniper Networks, using Ethernet or Fibre Channel from Brocade Communications Systems. The use of SCSI interfaces has been seen in data centers and server farms from companies like Google, Amazon, and Microsoft, where high-performance storage is required.

SCSI Devices and Peripherals

SCSI devices and peripherals include hard disk drives from Western Digital and Seagate Technology, tape drives from Quantum Corporation, and CD-ROM drives from Sony and Toshiba. Other devices, such as scanners from Epson and HP, and printers from Canon and Xerox, can also be connected to a SCSI interface. The use of SCSI devices and peripherals has been seen in mainframe computers from IBM and Unisys, as well as in supercomputers from Cray Inc. and Hewlett Packard Enterprise. The development of SCSI devices and peripherals has been influenced by the work of IEEE and the International Electrotechnical Commission (IEC), which have developed standards for the interface.

SCSI Command Set

The SCSI command set is a set of commands that are used to control and communicate with SCSI devices. The command set includes commands for data transfer, device control, and error handling, and is used by the host adapter to communicate with the devices connected to it. The SCSI command set is defined by the SCSI standards and is implemented by device manufacturers, such as Western Digital and Seagate Technology, to ensure compatibility and interoperability between devices from different manufacturers. The use of the SCSI command set has been seen in storage area networks (SANs) from companies like EMC Corporation and NetApp, as well as in network-attached storage (NAS) devices from Synology and Qnap. The development of the SCSI command set has been influenced by the work of ANSI and the Institute of Electrical and Electronics Engineers (IEEE), which have developed standards for the interface. Category:Computer hardware