what is diff between SCSI and iSCSI

[avizen9]

Hi
please help me to find out ans for diff between SCSI and iSCSI. what is use of it.

[Jeeshan]

Hi

iSCSI is the SCSI protocol mapped to TCP/IP and run over standard Ethernet technologies. This allows Ethernet networks to be deployed as SANs at a much lower TCO than Fibre Channel (FC).
Parallel SCSI and serial attached SCSI (SAS) are technologies designed to be inside a box such as DAS or within a storage array. They are not viable SAN technologies at this time.

The iSCSI on Ethernet (10/100/1000/10000) is a good viable external interconnect between application server initiators and storage targets. Parallel SCSI and SAS are good internal interconnects between the server and its internal storage or between the array controller and its drawers of hard disk drives (HDDs).

[Asif Sharif · Accepted solution]

SCSI interfaces provide for faster data transmission rates (up to 80 megabytes per second) than standard serial and parallel ports. In addition, you can attach many devices to a single SCSI port, so that SCSI is really an I/O bus rather than simply an interface.

Although SCSI is an ANSI standard, there are many variations of it, so two SCSI interfaces may be incompatible. For example, SCSI supports several types of connectors.

While SCSI has been the standard interface for Macintoshes, the iMac comes with IDE, a less expensive interface, in which the controller is integrated into the disk or CD-ROM drive. Other interfaces supported by PCs include enhanced IDE and ESDI for mass storage devices, and Centronics for printers. You can, however, attach SCSI devices to a PC by inserting a SCSI board in one of the expansion slots. Many high-end new PCs come with SCSI built in. Note, however, that the lack of a single SCSI standard means that some devices may not work with some SCSI boards.

The following varieties of SCSI are currently implemented:
# SCSI-1: Uses an 8-bit bus, and supports data rates of 4 MBps
# SCSI-2: Same as SCSI-1, but uses a 50-pin connector instead of a 25-pin connector, and supports multiple devices. This is what most people mean when they refer to plain SCSI.
# Wide SCSI: Uses a wider cable (168 cable lines to 68 pins) to support 16-bit transfers.
# Fast SCSI: Uses an 8-bit bus, but doubles the clock rate to support data rates of 10 MBps.
# Fast Wide SCSI: Uses a 16-bit bus and supports data rates of 20 MBps.
# Ultra SCSI: Uses an 8-bit bus, and supports data rates of 20 MBps.
# SCSI-3: Uses a 16-bit bus and supports data rates of 40 MBps. Also called Ultra Wide SCSI.
# Ultra2 SCSI: Uses an 8-bit bus and supports data rates of 40 MBps.
# Wide Ultra2 SCSI: Uses a 16-bit bus and supports data rates of 80 MBps.


iSCSI is Internet SCSI (Small Computer System Interface), an Internet Protocol (IP)-based storage networking standard for linking data storage facilities, developed by the Internet Engineering Task Force (IETF). By carrying SCSI commands over IP networks, iSCSI is used to facilitate data transfers over intranets and to manage storage over long distances. The iSCSI protocol is among the key technologies expected to help bring about rapid development of the storage area network (SAN) market, by increasing the capabilities and performance of storage data transmission. Because of the ubiquity of IP networks, iSCSI can be used to transmit data over local area networks (LANs), wide area networks (WANs), or the Internet and can enable location-independent data storage and retrieval.

Regards,
Asif Sharif

[dirk dierickx]

all info at wikipedia:
http://en.wikipedia.org/wiki/Iscsi