Admin Alert: A Quick Audit of Your IPL Parameters
June 15, 2005 Joe Hertvik
Being a mature operating system, i5/OS V5R3 (as well as several earlier versions of the OS/400 operating system) contains a number of system values that determine when, where, and how your system can be IPLed. As such, it’s worth performing a mini-IPL audit every once in a while just to familiarize yourself with the system’s IPL options as well as to insure that your IPL configuration meets your shop’s needs.
Inside i5/OS, IBM allows you to configure rules about your IPL strategy through a number of IPL-related system values. On the green screen, these values can be located and modified by specifying *SYSCTL in the System Value parameter (SYSVAL) of the Work with System Values command (WRKSYSVAL), as follows:
These values can also be accessed inside IBM’s iSeries Navigator program by right-clicking on your i5 system under the My Connections node, clicking on Properties from the pop-up menu that appears, and then configuring your options under the Restart tab on the system’s Properties dialogue. In both environments, IBM allows you to change most of your system’s IPL values. Here’s a list of the most common IPL values that could have an affect on your system IPL as well as some tips on how to best set each value:
1. The Date and time to automatically IPL system value (QIPLDATTIM) allows you to set a specific date and time when your system will automatically IPL. This is useful when you’ve loaded PTFs and you want the system to automatically IPL for PTF application during a low-traffic time period, such as a Sunday morning or on a holiday. QIPLDATTIM removes the requirement that you must be on site when you IPL your system.
But there is one pitfall when using QIPLDATTIM. Be careful when setting this value on a pre-V5R3 system where you have a primary partition and one or more secondary partitions on the same system. If you set your primary partition to automatically IPL at a certain date and time, all the secondary partitions will also IPL at that same time and date. This is because secondary partitions cannot run under OS/400 V5R2 or below without the primary partition being active, so don’t use this technique for primary partitions in those environment.
2. The Type of IPL to Perform value (QIPLTYPE) allows you to choose which type of IPL will be performed when your partition is powered on manually during a normal IPL. You have three choices. When set to the first choice (QIPLTYPE=0), the system will perform a normal unattended IPL. The second choice (QIPLTYPE=1) performs an attended IPL where the dedicated service tools screen comes up along with IBM’s full set of IPL screens. This option comes in handy when you are performing an attended i5/OS upgrade. The third option (QIPLTYPE=2) performs an attended IPL just like the QIPLTYPE=1 option, but it also brings up the system console in debug mode.
While option 2 may be useful for problem analysis by a service technician, it may not have much practical use for i5/OS system administrators. In most cases, you should probably make sure that this value is set to ‘0’ (its shipped value), especially if you are performing an automatic IPL by using the QIPLDATTIM system value.
3. The Maximum Time for PWRDWNSYS *IMMED system value (QPWRDWNLMT) specifies the maximum amount of time that the system will wait for jobs to end before powering down a partition using the Power Down System command (PRWDWNSYS) with the option to end the system immediately (*IMMED), like this:
QPWRDWNLMT is also used when an administrator issues a PWRDWNSYS command with the controlled option (*CNTRLD)–which specifies a set amount of time to wait for jobs to end before power down–and the controlled end delay time expires, such as on this command:
PWRDWNSYS OPTION(*CNTRLD) DELAY(3600)
If the delay time expires (3600 seconds, or sixty minutes, in this case) and there are still active jobs in the system, i5/OS will wait the additional amount of time specified in QPWRDWNLMT before immediately ending the jobs and powering down the system.
QPWRDWNLMT’s default value is 900 seconds (15 minutes).
4. The Automatic IPL After Power Restored value (QPWRRSTIPL) specifies whether or not the partition should automatically IPL when power is restored after a power failure. The default value is ‘0’, which disables this feature. On partitioned systems, this feature is limited because this action is controlled either from the primary partition or the hardware management console.
5. The Remote Power On and IPL system value (QRMTIPL) tell i5/OS whether a remote power on or an IPL can be initiated over a communications line. This determines whether or not a non-console user can restart your system, and, most times, QRMTIPL’s value should remain at ‘0’ (Not allowed, its default value). Fortunately, there are some safeguards on setting QRMTIPL on partitioned systems, where this value can only be changed from the primary partition, on the hardware management console (where you have to physically be standing in front of your machine), or from the service processor. But for most situations, it’s best to keep this value at ‘0’ to force users to be physically present in front or your i5 or iSeries box before they can turn off or turn on the machine.
6. The IPL Action with Console Problem system value (QSCPFCONS) tells OS/400 what to do if there is a console failure when your system is IPLing. The choices are to immediately end the IPL when the system console is not operational (option 0) or to continue the IPL as an unattended IPL (option 1). The shipped value is 1 on i5/OS V5R3, which is a reasonable value for systems running under a hardware management console (HMC) setup, where the system can be started, stopped, or modified without the benefit of a system console.
7. The IPS Status Indicator value (QIPLSTS) is an informational value that tells you which form of IPL last started the system. It cannot be changed but it does tell you whether the currently running system was IPLed from the Operator panel (when QIPLSTS contains a value of 0), an auto-IPL after power was restored (value=1), a restart IPL through the PWRDWNSYS command (value=2), a time of day IPL triggered by the QIPLDATTIM system value (value=3), or a remote IPL (value=4). Besides its informational value, QIPLSTS can be referred to in any recovery programs you write for abnormal IPLs or in your Startup program.(as determined in the QSTRUPPGM system value).
These are the basic options IBM provides for configuring and monitoring your IPL parameters. When used properly, they can help you maintain control over your PWRDWNSYS and IPL processes, making sure your system powers down and restarts exactly the way that you intended it to.