This IBM® Redbooks® publication provides advice and guidance for IBM z/OS® Version 1, Release 10 and subsystem system programmers. z/OS is an IBM flagship operating system for enterprise class applications, particularly those with high availability requirements. But, as with every operating system, z/OS requires planned IPLs from time to time. This book also provides you with easily accessible and usable information about ways to improve your mean time to recovery (MTTR) by helping you achieve the following objectives: - Minimize the application down time that might be associated with planned system outages. - Identify the most effective way to reduce MTTR for any time that you have a system IPL. - Identify factors that are under your control and that can make a worthwhile difference to the startup or shutdown time of your systems.