Front cover Introduction to Storage Area Networks Learn basic SAN terminology and component uses Introduce yourself to the benefits a SAN can bring Discover the IBM TotalStorage SAN portfolio Jon Tate Fabiano Lucchese Richard Moore ibm.com/redbooks International Technical Support Organization Introduction to Storage Area Networks July 2006 SG24-5470-03 Note: Before using this information and the product it supports, read the information in “Notices” on page xv. Fourth Edition (July 2006) This edition applies to the IBM TotalStorage portfolio. © Copyright International Business Machines Corporation 1999, 2003, 2006. All rights reserved. Note to U.S. Government Users Restricted Rights -- Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp. Contents Figures . xi Notices . xv Trademarks . xvi Preface . xvii The team that wrote this redbook. xviii Become a published author . xix Comments welcome. xx Chapter 1. Introduction. 1 1.1 What is a Storage Area Network? . 2 1.2 SAN components . 4 1.2.1 SAN connectivity . 5 1.2.2 SAN storage . 5 1.2.3 SAN servers . 6 1.3 The importance of standards. 6 1.4 Where are SANs heading? . 7 Chapter 2. How, and why, can we use a SAN? . 9 2.1 Why use a SAN? . 10 2.1.1 The problem . 10 2.1.2 The requirements . 12 2.2 How can we use a SAN?. 13 2.2.1 Infrastructure simplification . 13 2.2.2 Information lifecycle management . 14 2.2.3 Business continuity . 15 2.3 Using the SAN components . 15 2.3.1 Storage . 15 2.3.2 SAN connectivity . 17 2.3.3 Servers . 21 2.3.4 Putting the components together . 26 Chapter 3. Fibre Channel internals . 29 3.1 Firstly, why the Fibre Channel architecture? . 30 3.1.1 The SCSI legacy . 30 3.1.2 Why Fibre Channel? . 33 3.2 Layers . 36 3.3 Optical cables . 39 © Copyright IBM Corp. 1999, 2003, 2006. All rights reserved. iii 3.3.1 Attenuation . 39 3.3.2 Maximum power . 40 3.3.3 Fiber in the SAN . 41 3.3.4 Dark fiber. 43 3.4 Classes of service . 44 3.4.1 Class 1 . 44 3.4.2 Class 2 . 44 3.4.3 Class 3 . 44 3.4.4 Class 4 . 45 3.4.5 Class 5 . 45 3.4.6 Class 6 . 45 3.4.7 Class F . 45 3.5 Fibre Channel data movement . 46 3.5.1 Byte encoding schemes . 46 3.6 Data transport . 50 3.6.1 Ordered set . 50 3.6.2 Frames . 51 3.6.3 Sequences . 54 3.6.4 Exchanges . 54 3.6.5 In order and out of order . 54 3.6.6 Latency . 55 3.6.7 Open Fiber Control . 55 3.7 Flow control . 56 3.7.1 Buffer to buffer . 56 3.7.2 End to end. 56 3.7.3 Controlling the flow . 56 3.7.4 Performance . 57 3.8 Addressing . 57 3.8.1 World Wide Name . 58 3.8.2 Port address . 59 3.8.3 24-bit port address . 60 3.8.4 Loop address . 62 3.8.5 FICON address . 62 Chapter 4. Topologies and other fabric services . 69 4.1 Fibre Channel topologies . 70 4.1.1 Point-to-point. 71 4.1.2 Arbitrated loop. 72 4.1.3 Switched fabric . 73 4.2 Port types . 74 4.2.1 Domain ID . 76 4.3 Fibre Channel Arbitrated Loop protocols. 76 4.3.1 Fairness algorithm. 77 iv Introduction to Storage Area Networks 4.3.2 Loop addressing . ..