Admin Alert: Secrets Of The IBM i IPL Parameters
May 2, 2012 Timothy Prickett Morgan
IBM i operating systems contain a number of attributes that are used to control IPL processing when you start or restart a partition. Some attributes (such as Start To Restricted State) are well-known, while others are seldom looked at. This week, let’s take a look at your system’s IPL attributes and how they can help you perform specific functions on your system.
Viewing And Changing Your IPL Parameters
You can view and change your IPL parameters by typing in the Change IPL Attributes (CHGIPLA) command from a 5250 green screen and pressing the F4 key. When you do this, you’ll get a screen that looks something like this.
(Click graphic to enlarge.)
If you just want to view the IPL attributes without changing them, you can also use the Display IPL Attributes (DSPIPLA) command. DSPIPLA displays a similar screen to the CHGIPLA screen, except that you won’t be able to change any of the attributes.
For simplicity’s sake, you can generally divide your IPL attributes into the following subgroups.
Let’s take a look at each set of attributes and see how you can use them to modify your system startup process.
Attributes Affecting The IPL Process
These attributes affect what happens while the system is IPLing. Changing them allows you to affect how the IPL proceeds and what functions are performed during the IPL. They include:
Restart Type (RESTART)–Specifies which parts of the operating system are restarted. This parameter is used when you restart the system by using the Power Down System (PWRDWNSYS) command with the Restart after Power Down (RESTART) parameter set to *YES, like this:
This parameter has two settings: System Restart (*SYS); and Full Restart (*FULL). A *FULL restart will restart and reset the hardware associated with the partition; and it will restart the i operating system on that partition. A *SYS restart will only restart the operating system without resetting and restarting the hardware. The *SYS restart will also run more quickly than a *FULL restart and in most instances, you will only need to run a *SYS restart. The shipped RESTART value is *SYS.
Display Status (DSPSTS)–Determines whether and during which IPL types the system will display status messages as it is IPLing. By default, it displays IPL status messages for all IPLs (*ALL). It can also be set to only display status messages during an Attended IPL (*ATTEND); an Abnormal IPL (*ABNORMAL); during Attended or Abnormal IPLs (*SYS); or to suppress displaying any status messages during an IPL (*NONE).
Attributes That Start Other System Functions Or The System Startup Program
These attributes start or suppress other operating system functions from running after the IPL. These attributes include:
Start TCP/IP (STRTCP)–Specifies whether TCP/IP processing should be started by running the Start TCP/IP (STRTCP) command after the IPL completes or when the system comes out of restricted state. When set to *YES, TCP/IP is started. When set to *NO, TCP/IP is not started. The STRTCP parameter is ignored when the system IPLs into restricted state or when running an installation IPL. You should also note that the STRTCP parameter command contains four *YES/*NO parameters that will start the following TCP/IP-related functions on the system when the command executes.
Start To Restricted State (STRRSTD)–Specifies whether after an IPL, the system will be started to restricted state (*YES) or whether normal processing will occur (*NO). When set to *YES (restricted state), no system functions (including TCP/IP and all subsystems) will be started, and only the system console will be active. When set to *NO (normal processing), the system startup program (as defined in the QSTRUPPGM System startup system value) will be run. TCP/IP will also start in normal mode, provided the STRTCP IPL attribute is set to *YES or the startup program contains a STRTCP statement. If you set STRRSTD to *YES, i OS will IPL the system into restricted state the next time you IPL BUT the system will set STRRSTD back to *NO after the restricted IPL completes.
Attributes That Perform System Cleanup Or Recovery
These attributes specify additional system cleanup parameters that are executed during an IPL.
Spooled File Recovery (SPLFRCY)–Tells the system what to do with all of the spooled files on your systems when a job table is detected as damaged or if *YES is set for the following three other IPL attributes: Clear Job Queues (CLRJOBQ); Clear Output Queues (CLROUTQ); and Clear Incomplete Joblogs (CLRINCJOB). If neither situation exists, this parameter has no effect on IPL processing. SPLFRCY can be set to detach spooled files from their corresponding jobs and leave them on the system (*DETACH); or it can be set to remove all spooled files from the system (*REMOVE). SPLFRCY’s default value is *DETACH.
Clear Job Queues (CLRJOBQ)–Specifies whether to clear the job queues during an IPL. When set to *YES, all entries in job queues are cleared. When set to *NO, the system does not clear the job queues. Like the Start To Restricted State (STRRSTD) parameter, this parameter is set back to *NO (its initial value) after each IPL.
Clear Output Queues (CLROUTQ)–Specifies whether the system clears all output queues in libraries that are either in the auxiliary storage pool (ASP 1) or any of the basic user auxiliary storage pools (ASPs 2-32). *YES clears the output queues during IPL. *NO retains the spooled files. Note a *YES parameter can be overridden by the Spooled File Recovery parameter, if the Clear Job Queues and Clear Incomplete Joblogs parameters are also set to *YES.
Clear Incomplete Joblogs (CLRINCJOB)–*YES or *NO parameter that specifies whether to delete any pending job logs that have not yet been written. Like CLROUTQ, a *YES value in this parameter can be overwritten if the Clear Job Queues and Clear Output Queues parameters are also set to *YES.
Compress Job Tables (CPRJOBTBL)–Specifies whether the job tables should be compressed during IPL to remove unused entries.
Check Job Tables (CHKJOBTBL)–Specifies whether the system should perform damage checks on the system job tables during an IPL. CHKJOBTBL can either be set to *ABNORMAL (check job tables only during an abnormal IPL) or *ALL (job table checks are performed during all IPLs).
Rebuild Product Directory (RBDPRDDIR)–Specifies whether system product directory information should be rebuilt during the IPL. RBDPRDDIR can be set to *NONE (don’t rebuild the directory), *NORMAL (the product directory is fully rebuilt only during a normal IPL), *ABNORMAL (rebuild the directory only during abnormal IPLs), or *ALL (directories are rebuilt during all IPLs). This parameter is overridden to rebuild the product directory whenever a system install occurs.
Follow Me at My Blog, on Twitter, and on LinkedIn
Come check out my blog at joehertvik.com, where I focus on computer administration and news (especially IBM i and soon PureSystems); vendor, marketing, and tech writing news and materials; and whatever else I come across.
Joe Hertvik is the owner of Hertvik Business Services, a service company that provides written marketing content and presentation services for the computer industry, including white papers, case studies, and other marketing material. Email Joe for a free quote for any upcoming projects. He also runs a data center for two companies outside Chicago. Joe is a contributing editor for IT Jungle and has written the Admin Alert column since 2002.