Users Guide Serial Attached SCSI (SAS) Interface Manual Users Guide Serial Attached SCSI (SAS) Interface Manual ©2003, 2004, 2005, 2006 Seagate Technology LLC All rights reserved Publication number: 100293071, Rev. B May 2006 Seagate, Seagate Technology, and the Seagate logo are registered trademarks of Seagate Technology LLC. SeaTools, SeaFAX, SeaFONE, SeaBOARD, and SeaTDD are either registered trademarks or trade- marks of Seagate Technology LLC. Other product names are registered trademarks or trademarks of their owners. Seagate reserves the right to change, without notice, product offerings or specifications. No part of this publication may be reproduced in any form without written permission of Seagate Technology LLC. Revision status summary sheet Revision Date Writers/Engineers Notes Rev. A 11/11/04 J. Coomes Initial release. Rev. B 05/07/06 C. Chalupa, J. Coomes, G. Houlder All. Contents 1.0 Interface requirements. 1 1.1 Acknowledgements . 1 1.2 How to use this interface manual . 1 1.2.1 Scope . 2 1.2.2 Applicable specifications . 2 1.2.3 Other references . 3 1.3 General interface description. 3 1.3.1 Introduction to Serial Attached SCSI Interface (SAS) . 3 1.3.2 The SAS interface . 3 1.3.3 Glossary . 5 1.3.4 Keywords . 16 1.4 Physical interface characteristics. 17 1.5 Bit and byte ordering . 17 2.0 General . 19 2.1 Architecture . 19 2.1.1 Architecture overview . 19 2.1.2 Physical links and phys . 19 2.1.3 Ports (narrow ports and wide ports) . 20 2.1.4 SAS devices . 21 2.1.5 Expander devices (edge expander devices and fanout expander devices) . 22 2.1.6 Service delivery subsystem. 23 2.1.7 Domains . 23 2.1.8 Expander device topologies . 24 2.1.8.1 Expander device topology overview . 24 2.1.8.2 Edge expander device set . .24 2.1.8.3 Expander device topologies. .25 2.1.9 Pathways. 26 2.1.10 Connections . 27 2.2 Names and identifiers . 30 2.2.1 Names and identifiers . 30 2.2.2 SAS addresses . 30 2.2.3 Hashed SAS address . 31 2.2.4 Device names . 31 2.2.5 Port identifiers . 31 2.2.6 Phy identifiers . 31 2.3 Resets . 32 2.3.1 Reset overview . 32 2.3.2 Hard reset . 32 2.4 I_T nexus loss . 33 3.0 Phy layer . 35 3.1 Phy layer overview . 35 3.2 Encoding (8b10b) . 35 3.2.1 Encoding overview . 35 3.2.2 8b10b coding introduction . 36 3.3 Encoding and decoding . 36 3.4 Out of band (OOB) signals . 37 3.5 Phy reset sequences . 42 3.5.1 Phy reset sequences overview . 42 3.5.2 SAS to SAS phy reset sequence . 42 3.5.2.1 SAS OOB sequence . .42 3.5.2.2 SAS speed negotiation sequence . 44 3.5.3 Phy reset sequence after devices are attached . 47 3.6 DWS (dword synchronization) . 49 3.6.1 Acquiring DWS . 49 3.6.2 Losing DWS . ..