How Much Temporary Storage Is In Use And Who Is Using It?
July 21, 2015 Pete Massiello
I recently visited the site of a company that had a problem of increasing disk utilization. The staff had run all the GO DISKTASK reports and nothing seemed to be getting bigger. Unfortunately, there hasn’t been an easy way of finding who is using temporary storage. Displaying the amount of used temporary storage was so obscure that most System Administrators had no idea where to look. Let me show you how to see: (1) the amount of temporary storage that is being used; and (2) the jobs are using the most.
Temporary storage is mostly associated with jobs on your system, and it can certainly grow. This temporary storage is composed of temporary objects, temporary indexes, and other internal structures. Failure to control and manage this could overflow your disks. When the system is IPLed all temporary storage is released, but IBM recommends that we don’t need to IPL that often. I have seen the disks on systems fill completely up because there was a runaway job just creating temporary storage. The problem has been it wasn’t easy to find, until now.
Below is the top right-hand side of a Work with System Status (WRKSYSSTS) command from a system at IBM i V5R4, 6.1, or 7.1. You can see that this partition has 1.7TB in total (System ASP) and is currently using 59.68% (% System ASP used) of the disk, and in all the ASPs the (Total Aux Stg) total storage is 1.7TB. We also know that there is only one ASP because the System ASP and the Total Aux Stg are the same. Now, notice the next two lines. Current unprotected used is 4,746 MB (or 4.7GB) of temporary storage. That is the amount of temporary storage being used right now. The maximum unprotected is the largest amount it has gotten to since the last IPL.
Now, notice the screen capture below of an IBM i 7.2 system. The WRKSYSSTS command now states Current temporary storage used and Peak temporary used. Certainly this is more easily understood. It states the same exact thing as before, but labeled so people understand what it is.
Ok, I am saving the best for last. While we know the total amount of storage being used, it really helps us if we know which jobs are causing the problem. Now, with IBM i 7.2, we can use the Work with Active Jobs (WRKACTJOB) command and press F11 (Function key 11) twice to see the following display.
Check out the last column. We can easily see how much temporary storage is being used by each job. If you want to sort the jobs by usage of temporary storage, put your cursor on the Temporary Storage column and press F16.
You certainly should run this command on your system to get an idea of first how much temporary storage is being used, and then which jobs are using the most temporary storage. This is yet another great reason to upgrade to IBM i 7.2.
Pete Massiello has been working with the AS/400, iSeries, and IBM i since 1989, focusing on systems management and technical support. He has held numerous technical positions throughout his career. He is the President of iTech Solutions Group, an IBM Premier Business Partner delivering solutions and services to IBM i shops throughout the world. He is a member of IBM’s certification test writing team, and an IBM Certified Systems Expert with certifications in iSeries Design, Administration, Virtualization, Implementation, LPAR, and HMC management. Pete has a B.S. in Computer Science from Hofstra University and an MBA from the University of New Haven. He was President of COMMON from 2010 to 2012, and again in 2014. Pete is a COMMON Hall of Fame speaker and a frequent speaker at user groups all over the world. In 2011 IBM established the Champions award for Power Systems. Pete was one of the first recipients.