Using IPL levels

IPL levels can be used to group similar objects and perform a controlled system start-up or shutdown. You can give IPL levels names (such as BASIC, NETWORK, DATABASE, and ONLINE), and associate objects with each level that you specify. You can specify a timeout value for each IPL level to make sure the level completes processing within the timeframe you want when starting or stopping.

We recommend that you use IPL levels if you want to perform maintenance but only need a certain set of objects up or down, or if you want to be able to verify your system as each group of objects is started or stopped. You can also use IPL levels for disaster recovery sites, where only part of the system is running. After you restore the system, you can start new groups of objects until you have restored all your data sets and files.

When using IPL levels, you can pause a system startup or shut down by using the predefined IPL levels that identify which objects need to be up or down as a group.

Once the IPL levels are defined, you can associate objects with the desired IPL level. All objects that specify the same IPL level name will be processed as a group when started or stopped. Any object that does not specify an IPL level name is grouped with the <null> level. This group of objects will start last when doing START IPLLEVEL commands and stop first when doing STOP IPLLEVEL commands. Any object that specifies an IPL level attribute that is not defined in IPLORDER is grouped with the <null> level. 

When IPL levels are used during an IPL, TOM will attempt to start all objects in the first IPL level defined in IPLORDER.  To start subsequent levels, the START IPLLEVEL command is issued. Each START IPL LEVEL command will start the objects in the next defined IPL level. Once all IPL levels defined in IPLORDER are started, the next START IPLLEVEL command will start objects in the <null> level (those that do not specify the IPL level attribute or specify an IPL level that is not defined in IPLORDER).

To use IPL levels for a controlled shutdown, the STOP IPLLEVEL command is used. Each time the STOP IPLLEVEL command is issued, it stops all the objects associated with the current level and then sets the current level to the previously defined level in IPLORDER. If all the levels are started, the first STOP IPLLEVEL command will stop all objects associated with the <null> level and set the current IPL level to the last level defined in IPLORDER.  When the current IPL level is the first level defined in IPLORDER, you must perform a SHUTSYS to shut the system down.

Important

If a timeout occurs on START IPLLEVEL or STOP IPLLEVEL processing, TOM will continue to try to bring all objects in that level to the desired state. You might receive a timeout notification message and later receive a message that indicates the level is complete.

For more information about controlled starting of objects during an IPL with IPLLEVEL, see Controlled starting of objects during IPL with IPLLEVEL.

 

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