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1. What is the definition of Serial Attached SCSI?
Serial Attached SCSI (SAS) is the logical evolution of SCSI that satisfies the enterprise data center requirement for scalability, performance, reliability and manageability, while leveraging a common electrical and physical interface with Serial ATA (SATA). This compatibility provides users with unprecedented choices for server and storage subsystem deployment.
2. Why was Serial Attached SCSI developed?
was developed to address I/O and direct attach storage requirements that traditional parallel SCSI cannot meet. It provides universal interconnect with SATA, while offering logical SCSI compatibility along with SCSI reliability, performance and manageability.
3. What role does the SCSI Trade Association (STA) play in the standardization process?
STA's role in the standardization process is to influence the developmental direction of SAS specifications, based on future market needs as defined by STA members. The INCITS T10 Committee has direct responsibility for specification development and ANSI fosters development of technology standards.
4. What other responsibilities does STA have for Serial Attached SCSI?
STA promotes SAS technology and educates the industry - targeting enterprise storage OEMs, VARs, SIs, IT and end users - all of which want solutions for their current and future storage requirements. As the need for more volume and flexible storage usage increases, SAS has become more attractive to the industry, due, in part, to its compatibility with SATA, as both SAS and SATA drives can be installed and controlled in the same SAS system.
5. When did Serial Attached SCSI-based systems enter the market?
As of fall, 2005, 3Gb/s SAS systems entered the market and are now (2007) shipping in volume quantities.
6. How does Serial Attached SCSI benefit the storage industry?
SAS leverages the proven SCSI technologies that customers expect in data center environments, providing robust solutions and generational compatibility. SAS is based on a serial interface, allowing for increased device support and bandwidth scalability, as well as reducing the overhead impact that challenges today's SCSI storage environments. SAS utilizes SATA development for smaller cable connectors, providing customers a downstream compatibility with desktop class ATA technologies.
Simplified routing enables a new generation of dense devices such as small form factor (SFF) hard drives, permitting storage solutions to scale externally.
7. What are the end-user benefits of Serial Attached SCSI?
Key end-user benefits include enterprise class robustness, investment protection in compatible SCSI software and middleware and the choice of direct-attach storage devices (SAS or SATA or both) in a single SAS system. In addition, longer cabling distances, smaller form factors and greater addressability will lead to a new level of flexibility when deploying mainstream data-center servers and subsystems. SAS is based on the foundation of the industry-leading SCSI specification and as a result, reliability, familiarity and peace of mind will help satisfy user's needs for continuity in the data center.
8. What are the estimated costs of Serial Attached SCSI solutions?
Today, 3Gb/s SAS costs do not differ significantly from those of parallel SCSI solutions. The SAS cost per unit of performance is significantly better than parallel SCSI due to its notable performance advantages. This metric will continue to improve with each new generation of SAS.
9. Are Serial Attached SCSI connectors compatible with those of SCSI server and storage solutions?
No, the two are not compatible. SAS connectors are much smaller than SCSI connectors. (as explained in # 6).
10. How is Serial Attached SCSI complementary to Serial ATA?
SAS complements SATA by adding dual porting, full duplex and device addressing, plus it offers higher reliability, performance and data availability services, as well as logical SCSI compatibility. STA will continue to enhance these metrics as the specification evolves, including increased device support and longer cabling distances. Most importantly, SAS and SATA are complementary technologies based on a universal interconnect, where SAS customers can choose to deploy cost-effective SATA drives in a SAS storage environment.
11. Can I use Serial Attached SCSI hard drives in my Serial ATA workstation or desktop PC?
While not native, SAS hard drives can be used on SATA desktops and workstations by adding a host bus adapter.
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