Serial Attached SCSI technologies and architectures, 4th edition

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Table 2: Physical link rates per direction
Physical link rate
Generation
Bandwidth for a 1x
connection
4x bandwidth
1.5 Gb/s
SAS-1, SAS-1.1, SATA Revision 1.0
150 MB/s
600 MB/s
3 Gb/s
SAS-1, SAS-1.1, SATA Revision 2.0
300 MB/s
1200 MB/s
6 Gb/s
SAS-2, SAS-2.1, SATA Revision 3.0
600 MB/s
2400 MB/s
SAS/SATA interoperability
The SAS interface lets you use SAS drives, SATA drives, or a mixture of these drives in the same
storage enclosure. SAS architecture allows flexible solutions ranging from entry-level NAS in desktop
environments to mission-critical RAID systems (Figure 3). With this broad range of storage solutions,
you can choose storage devices based on reliability, performance, and cost.
Figure 3: Examples of solutions available with SAS architecture
SAS supports three communication protocols:
Serial Management Protocol (SMP) manages the point-to-point topology of expanders and
enclosures.
Serial SCSI Protocol (SSP) facilitates communication with SAS devices and existing SCSI software.
SATA Tunneling Protocol (STP) lets SAS controllers communicate with SATA devices through
expanders.
SAS topologies
SAS makes it possible to create highly scalable topologies—internal, external, or both—giving you
the flexibility to design and deploy a range of solutions. SAS controllers use STP to communicate with