Overview
ISO/IEC 14776-153:2015 - Serial Attached SCSI - 2.1 (SAS-2.1) specifies the physical layer of the Serial Attached SCSI (SAS) interconnect. The standard defines electrical, mechanical and signaling requirements for SAS links - including connectors, cable assemblies, backplanes, transmitter/receiver (Tx/Rx) characteristics, compliance points and test methods. It is a normative reference for designers, test engineers and vendors who need to ensure reliable high-speed SAS interconnect interoperability.
Key topics and technical requirements
- Physical layer scope: definitions of phys, physical links and phy test functions for SAS interconnects.
- Connectors and cable assemblies: detailed geometry and pinning for Mini SAS, Mini SAS HD, Micro SAS, Mini SAS 4x/4i/8i and related receptacles and plugs, plus SATA connector/cable coexistence considerations.
- Backplanes and internal/external cable environments: requirements for drive, enclosure and controller topologies and associated compliance points.
- Tx/Rx electrical characteristics: transmitter and receiver specs, transients, eye masks, jitter transfer function (JTF), and jitter tolerance patterns.
- S-parameters and channel limits: conventions for defining maximum S-parameter limits and compliance points for signal integrity.
- Test loads and measurement models: zero‑length, TCTF and low‑loss test loads; reference transmitter loads; included Touchstone models in informative annexes.
- Signal control and special signaling: Out-of-band (OOB) signals, SATA port selection signaling, Spread Spectrum Clocking (SSC), and non-tracking clock architectures.
- Active cable assemblies: characteristics and power/voltage detection (informative annex content).
- Normative and informative annexes: jitter tolerance pattern (JTPAT), SASWDP, StatEye, signal performance measurements and measurement guidance.
Practical applications - who uses this standard
- Hardware and PCB design engineers implementing SAS controllers, backplanes, enclosures and drive interfaces.
- Cable and connector manufacturers producing compliant SAS and SAS/SATA mixed assemblies.
- Test and validation teams performing signal integrity, jitter and compliance testing for SAS links.
- Systems integrators and OEMs ensuring interoperability of storage enclosures, host adapters and drives.
- Certification bodies and laboratories performing compliance verification to reduce interoperability issues.
Related standards
- Other parts of the ISO/IEC 14776 SCSI family (SAS and SCSI command/specification parts) and industry SATA specifications that define protocol and connector interoperability.
- Informative annexes in ISO/IEC 14776-153 provide measurement models and test patterns that complement laboratory test plans.
By following ISO/IEC 14776-153:2015 (SAS-2.1), implementers ensure robust, interoperable high‑speed SAS physical-layer designs, improved signal integrity, and consistent methods for compliance testing - essential for reliable enterprise storage systems.
Open preview (PDF)Information technology — Small Computer System Interface (SCSI) — Part 153: Serial Attached SCSI - 2.1 (SAS-2.1)
