iCan Blog Archive

Quite some time ago, I wrote a blog on Understanding Disk Space Usage. Near the end of that article, I mentioned that Collection Services collects storage usage data in the QAPMJOBMI file.

Late last year, there were additional enhancements to Navigator for i, which included updates to the Performance Data Investigator (PDI). With the Fall 2013 PDI enhancements, you can now visualize these Collection Services storage allocation metrics. You will now find some new charts that will show the storage usage on your system over time. These charts display storage allocation for both permanent and temporary storage.

Additional charts for Temporary Storage were added at a later point in time, as reviewed in Part 4 of the temporary storage tracking blog series.

In PDI, open Collection Services then expand the folder named Storage Allocation. In this folder are two charts to display storage allocation information.

Storage Allocation/Deallocation Overview
This perspectives includes two charts; one displays an overview of the storage allocated for the partition overall and the other displays an overview of the storage deallocated for the partition.

Here is an example of the storage allocation overview chart:

And this is an example of the storage deallocation overview chart:

From either of these overview charts you can drill into storage allocation/deallocation by thread or task.

Storage Allocation/Deallocation by Thread or Task

This graph displays the storage allocated or dealloacted by job or thread. You can then view the details for one job or thread over time.

Here is an example of this graph:

From here, we could even go look at the details of one of the jobs, where we can see how much storage the specific job allocated and deallocated over time.

Similar to the partition overview charts, when displaying storage allocation and deallocation by thread or task, there are two charts, one for storage allocated and a second for storage deallocated. Here’s an example of the Storage Allocation for on Thread or Task chart.

If you think you have a storage leak in your system, the Collection Services data, along with the new support in PDI to visualize this information, is another useful diagnostic tool.

The wonderful thing about looking at Collection Services data is that you can see what has been happening over time. With interfaces such as Work with System Activity (WRKSYSACT), you see what the values are right now. Collection Services can help you understand what was happening in the past to help you understand how you got to where you are now.

This blog post was edited for currency on April 11, 2020.

This blog post was originally published on IBMSystemsMag.com and is reproduced here by permission of IBM Systems Media.