Reducing System i ™ IPL Time
This report describes ways you can control how long it takes to start your i5/OS system. The Initial Program Load (IPL) for an i5/OS system is made up of three major stages. First the hardware is powered up, second the Licensed Internal Code is initialized, and third the operating system is started. This report focuses on performance aspects of operating system IPLs that change based on how you configure and use your system.
A normal IPL occurs after the system is powered down with the Power Down System (PWRDWNSYS) command and no jobs have ended abnormally. All other IPLs are abnormal for i5/OS. An abnormal IPL takes longer because of additional recovery and verification needed. Message CPI091D (Previous ending abnormal, reason code &1) is sent to the history log during an abnormal IPL. This message gives the reason why the system end was abnormal. If you cannot use the Power Down System command to end the system, use option 7=Delayed power off from the panel or service tools. Avoid using 8=Immediate power off or 3=IPL restart as they can cause a significantly longer abnormal IPL.
The following areas have an impact on IPL performance:
- Jobs
Cleaning up jobs and spooled files. Starting jobs and preparing an runtime environment. - File systems
Recovering database files, journals, and directories. Mounting file systems. ASPs and independent ASPs. - Configuration
Recovering user profiles and libraries. Varying on devices. Setting IPL attributes.
Following are suggestions that could reduce your IPL time. Some of these suggestions could have an effect on runtime performance or ease of operating your system.
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