Front cover High Availability On the AS/400 System A System Manager’s Guide Tools and solutions to improve your highly available AS/400 system Components for a successful high availability system Hardware options for high availability Redpaper Susan Powers Nick Harris Ellen Dreyer Andersen Sue Baker David Mee ibm.com/redbooks International Technical Support Organization High Availability On the AS/400 System: A System Manager’s Guide June 2001 Take Note! Before using this information and the product it supports, be sure to read the general information in Appendix H, “Special notices” on page 183. First Edition (June 2001) This edition applies to Version 4, Release Number 5 of OS/400 product number 5769-SS1. Comments may be addressed to: IBM Corporation, International Technical Support Organization Dept. JLU Building 107-2 3605 Highway 52N Rochester, Minnesota 55901-7829 When you send information to IBM, you grant IBM a non-exclusive right to use or distribute the information in any way it believes appropriate without incurring any obligation to you. © Copyright International Business Machines Corporation 2001. All rights reserved. Note to U.S Government Users - Documentation related to restricted rights - Use, duplication or disclosure is subject to restrictions set forth in GSA ADP Schedule Contract with IBM Corp. Contents Preface . ix The team that wrote this Redpaper . ix Comments welcome . xi Part 1. What is high availability? . .1 Chapter 1. Background. .3 1.1 When to consider a high availability solution . .3 1.1.1 What a high availability solution is. .3 1.2 What high availability is. .5 1.2.1 Levels of availability . .6 1.3 Determining your availability requirements . .7 1.4 Determining how high you need to go . .7 1.5 Estimating the value of availability . .8 1.6 iSeries factors for maximum availability . .9 1.7 Scheduled versus unscheduled outage . .10 1.7.1 Scheduled outages . .11 1.7.2 Unscheduled outages . .11 1.8 Comparison to planned preventive maintenance (PPM) . .11 1.9 Other availability definition considerations . .12 Chapter 2. Developing an availability plan . .15 2.1 The business plan. .15 2.1.1 Project scope and goal definition. .16 2.2 Human resources . .16 2.2.1 Project organization . .17 2.3 Communication and sponsorship . .17 2.4 Service level agreements . .18 2.5 Third party contracts . .18 2.5.1 Application providers. .18 2.5.2 Operating system provider . .19 2.5.3 Hardware providers. .19 2.5.4 Peripheral equipment . .19 2.5.5 Facilities . .20 2.6 Verifying the implementation . .22 2.6.1 Documenting the results . .22 2.7 Rollout . .22 Chapter 3. High availability example solutions . .25 3.1 A high availability customer: Scenario 1 . .25 3.2 A large financial institution: Scenario 2 . .26 3.2.1 Benefits. .28 3.3 A large retail company: Scenario 3 . .28 3.4 A small manufacturing company: Scenario 4. .29 3.5 A distribution company: Scenario 5 . .30 Part 2. AS/400 high availability functions . .33 Chapter 4. Hardware support for single system high availability . .35 4.1 Protecting your data . .35 iii 4.2 Disk protection tools . 35 4.3 Disk mirroring . 36 4.3.1 Standard mirrored protection . 37 4.3.2 Mirrored protection: Benefits . 38 4.3.3 Mirrored protection: Costs and limitations . 39 4.3.4 Determining the level of mirrored protection. 40 4.3.5 Determining the hardware required for mirroring . 44 4.3.6 Mirroring and performance. 45 4.3.7 Determining the extra hardware required for performance . 46 4.4 Remote DASD mirroring support . 46 4.4.1 Remote load source mirroring . 47 4.4.2 Enabling remote load source mirroring. 47 4.4.3 Using remote load source mirroring with local DASD . 47 4.5 Planning your mirroring installation . 48 4.5.1 Comparing DASD management with standard and remote mirroring 49 4.6 Device parity protection . 49 4.6.1 How device parity protection affects performance . 51 4.6.2 Using both device parity protection and mirrored protection. 52 4.7 Comparing the disk protection options . 52 4.8 Concurrent maintenance . 54 4.9 Redundancy and hot spare . 55 4.10 OptiConnect: Extending a single system . 55 4.11 Cluster support . 57 4.12 LPAR hardware perspective . 58 4.12.1 Clustering with LPAR support . 59 4.13 UPS. 60 4.14 Battery backup . 60 4.15 Continuously powered main storage . 61 4.16 Tape devices . 61 4.16.1 Alternate installation device . 61 Chapter 5. Auxiliary storage pools (ASPs). 63 5.1 Deciding which ASPs to protect . 63 5.1.1 Determining the disk units needed . 64 5.2 Assigning disk units to ASPs . 65 5.3 Using ASPs . 65 5.3.1 Using ASPs for availability . 66 5.3.2 Using ASPs to dedicate resources or improve performance. 66 5.3.3 Using ASPs with document library objects . 67 5.3.4 Using ASPs with extensive journaling . 68 5.3.5 Using ASPs with access path journaling . 68 5.3.6 Creating a new ASP on an active system. 68 5.3.7 Making sure that your system has enough working space . 69 5.3.8 Auxiliary storage pools: Example uses. 69 5.3.9 Auxiliary storage pools: Benefits . 70 5.3.10 Auxiliary storage pools: Costs and limitations . 70 5.4 System ASP . 71 5.4.1 Capacity of the system ASP. 71 5.4.2 Protecting your system ASP . 71 5.5 User ASPs. 71 5.5.1 Library user ASPs . ..