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 Introduced in 2003, serial attached SCSI (SAS) superseded the parallel SCSI interface and is widely used in datacenters where large numbers of drives are required (see illustration below).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.
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References in periodicals archive ?
It is suitable for adding multiple hot-swappable Serial ATA or Serial-Attached SCSI drives, even in computers with a limited number of drive bays available--appropriate for adding removable storage for backups or RAID storage systems.
"It's an optional software license we're adding for remote replication, but very few products in the entry level space include remote replication."<p>HP also increased the number of drives available in the P2000 G3 from 60 3.5-in serial ATA (SATA) drives to 96 drives and from 99 2.5-in serial-attached SCSI (SAS) drives to 194 SAS drives.
(NASDAQ:SMC), San Jose, Calif., a leader in application-optimized, high performance server solutions, has released a new line of high-density 3U Serial-attached SCSI (SAS) storage chassis that support 16 hot-swap 3.5-inch SAS/SATA drives.
The PS3700X serial-attached SCSI storage array provides an option for IT organizations to balance capacity and performance requirements for priority workloads such as Microsoft Exchange Server, SQL Server, Oracle databases and server virtualization projects.
The All-in-One Storage Manager also features mixed drive support, which means customers can leverage the cost efficiencies of serial ATA (SATA) with the speed and reliability of serial-attached SCSI (SAS).The HP AiO1200 is available immediately with 12 drive bays, up to nine terabytes of capacity and SATA or SAS options.XFX 600i boardsl Graphics specialist XFX has taken its first steps into the motherboard market with the launch of its 600i series of boards.
It offers an option to incorporate one or two Dual-Core Intel Xeon 5100 series processors, along with a choice of enterprise-class Serial-Attached SCSI (SAS) or high-capacity Serial ATA (SATA) hard drives.
Cost-effective SATA (serial ATA) and SAS (serial-attached SCSI) put high capacity and high performance disk into the hands of SMB.
Based on SiliconStor's patent- pending AAMUX technology, the new SS1300 device enables storage system manufacturers to cost-effectively build enterprise storage systems that can accommodate both low cost, high capacity serial ATA (SATA) and serial-attached SCSI (SAS) hard drives without sacrificing reliability or data availability.
Unrelenting demand for more communications bandwidth for data center networking is challenging interconnect technologies, such as Ethernet, Infiniband, Fibre Channel, and Serial-Attached SCSI (SAS).
Built for 10-Gigabit Ethernet and Category 7a premise wiring systems, the ARJ45 Category 7a modular plug and jack can be used as a replacement in closed-loop InfiniBand, Fibre Channel, EyeMAX, serial-attached SCSI, PCI express and microTCA applications.
SATA is slightly slower and less extensible than SCSI, Serial-Attached SCSI (SAS) and Fibre Channel drives.