serial attached SCSI


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serial attached SCSI

A standard hardware interface for storage drives. Introduced in 2003, serial attached SCSI (SAS) superseded the parallel SCSI interface and is widely used in datacenters where large numbers of drives are required (see illustration below).

SAS drives are generally faster than SATA drives and more reliable, but are also more costly. Although SATA drives can be connected to a SAS interface, SAS drives require an adapter to hook up to a SATA controller (see SATA and SATA Express).

SAS is a point-to-point architecture that uses a controller (host bus adapter) with two full-duplex channels that operate simultaneously. Each channel (SAS port) transfers data at 3, 6 or 12 Gbps in each direction. In contrast, the consumer-oriented SATA interface has only one channel.

SAS Protocols: SSP, STP and SMP
The Serial SCSI Protocol (SSP) is used for SAS drives, and the Serial ATA Tunneling Protocol (STP) is employed for SATA drives. Expanders use the Serial Management Protocol (SMP). See SCSI and hard disk interfaces.


Massive Scalability
SAS channels (ports) can connect to a single drive or to an expander that connects up to 128 drives (or host bus adapters). A Fanout Expander can connect Edge Expanders, and one system can support 16,256 drives.







Dual Ports for Fault Tolerance
SAS drives use the same form factor as Serial ATA (SATA) for the cable connector but add a second port for connection to two controllers or expanders for fault tolerance.
References in periodicals archive ?
CEVA licenses a family of programmable DSP cores, associated SoC system platforms and a portfolio of application platforms including multimedia, audio, Voice over Packet (VoP), Serial Attached SCSI (SAS) and Serial ATA (SATA).
Reducing SAN Costs and Complexity with iSCSI and Serial Attached SCSI
Seagate's serial I/O expertise and early R&D investment into developing Serial Attached SCSI will provide customers with best-in-class, reliable, and time-to-market products.
T10 forwarded Serial Attached SCSI to INCITS at our May 8, 2003 meeting, where it will go through a 45-day public review period," said John Lohmeyer, Chair of the T10 Technical Committee and Principal Engineer, LSI Logic.
Seagate Technology today announced the SAS Knowledge Center, an online resource to educate and prepare IT professionals and system builders for the transition to Serial Attached SCSI (SAS) technology in the enterprise.
Serial Attached SCSI, the successor technology to the parallel SCSI interface, leverages proven SCSI functionality and promises to greatly build on the existing capabilities of the enterprise storage connection.
ATA and Serial Attached SCSI - August 19, 2004, 9:30-10:45 a.
2009 will be a watershed year for Serial Attached SCSI as volume OEM shipments continue to increase and new 6Gb/s SAS products are readied for industry introductions," said Harry Mason, president of STA.
Serial Attached SCSI is the logical evolution of SCSI, including long-established software advantages and the Serial ATA electrical and physical connection interface.
Seagate Technology , the world's leading provider of disc drive products and technologies, today revealed its latest industry-first demonstration showing interoperability between multiple Serial Attached SCSI (SAS) and Serial ATA (SATA) disc drives all running within the same storage array.
AUSTIN, Texas -- The family of 3M brand Serial Attached SCSI (SAS) interconnects has expanded to include three additional products: a vertical through-hole receptacle with 29 positions; a hybrid receptacle with 29 positions, including surface mount signal leads and through-hole power tails; and a special 22-position SAS host receptacle, which was designed without a secondary signal port to eliminate unnecessary or unused contacts.
This exclusive roundtable was held May 28, 2004 on Serial Attached SCSI (SAS) with emphasis on the special plugfest session for SAS/SATA interoperability on June 23-24 at the University of New Hampshire, I/O Lab.