An Introduction to z/VM Single System Image (SSI) and Live Guest Relocation (LGR)

An IBM Redbooks publication

Published 18 April 2012, updated 31 March 2016

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ISBN-10: 0738436623
ISBN-13: 9780738436623
IBM Form #: SG24-8006-00
(134 pages)

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Authors: Lydia Parziale, Anthony Bongiorno, Howard Charter, Jo Johnston, Volker Masen, Clovis Pereira, Sreehari Somasundaran, Srivatsan Venkatesan


IBM® z/VM® 6.2 introduces significant changes to z/VM in the form of multi-system clustering technology allowing up to four z/VM instances in a single system image (SSI) cluster. This technology is important, because it offers clients an attractive alternative to vertical growth by adding new z/VM systems. In the past, this capability required duplicate efforts to install, maintain, and manage each system. With SSI, these duplicate efforts are reduced or eliminated.

Support for live guest relocation (LGR) allows you to move Linux virtual servers without disruption to the business, helping you to avoid planned outages. The z/VM systems are aware of each other and can take advantage of their combined resources. LGR enables clients to avoid loss of service due to planned outages by relocating guests from a system requiring maintenance to a system that remains active during the maintenance period.

Together, the SSI and LGR technologies offer substantial client value, and they are a major departure from past z/VM practices.

This IBM Redbooks® publication gives you a broad understanding of the new SSI architecture and an overview of LGR. We show an LGR example that shows a typical SAP user environment. In our example, the SAP Application Server Central Instance resides on a Linux on System z® guest and an IBM DB2® 10 database server runs on z/OS®.

This book is written for IT architects, who design the systems, and IT specialists, who build the systems.

Table of contents

Chapter 1. Introduction
Chapter 2. Single system image (SSI) overview
Chapter 3. Live guest relocation (LGR) overview
Chapter 4. Scenario one: Creating a single system image cluster with four new z/VM members
Chapter 5. Scenario two: Converting two existing stand-alone z/VM systems to a single system image cluster
Appendix A. Frequently asked questions
Appendix B. New and updated commands
Appendix C. Additional material

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