How Much Temporary Storage Am I Using?
October 28, 2009 Hey, Joe
My i5/OS partition disk storage is filling up and it hit 85 percent utilization today. How do I tell how much temporary storage space my system is using? If there’s a lot of temporary storage, what can I do about it? I heard that if you IPL a partition, you can reduce disk usage.
While an IPL can reclaim temporary storage space, it’s wise to first check out how much temporary space is being used on the system, just to see if it’s worth your while to IPL. Since iSeries, System i, and Power i machines generally run for months at a time, you probably want to ensure that you’ve done everything possible before you IPL the system. Here’s a quick drill for examining temporary storage and for possibly doing something about it.
First, use this IBM-provided equation for calculating temporary storage utilization in a partition.
You can retrieve the numbers for this equation from the Work with System Status (WRKSYSSTS) command display. The trick is to only focus on the numbers in the Auxiliary Storage area, which are found in the upper right-hand section of the WRKSYSSTS screen. Here’s a sample of what that area might look like on a system where temporary storage is under control.
On this system, the System ASP contains 3169 G of storage (about 3 Terabytes), which will be used for the Total System ASP Storage Number in your equation. It’s important to note that even though we are talking about temporary storage for system jobs, temporary storage is still written to system Auxiliary Storage Pool (ASP) disk so we use the System ASP value in the calculation. The Current Unprotected Used number (21531 M) can also be plugged directly into the equation from this screen.
Using these numbers, here’s what the equation to calculate the Temporary Disk Storage Utilization value for this system looks like.
Since the Current Unprotected Used Storage number is listed in Megabytes and the Total System ASP Storage number is listed in Gigabytes, it’s necessary to divide the resulting percentage by 10 to get the actual percentage used. For this example, temporary storage utilization is under 1 percent so there isn’t an issue with reclaiming storage. But let’s look at another example where temporary storage may be a real problem. We’ll start with these WRKSYSSTS statistics.
Which gives us the following equation for temporary storage disk utilization.
IBM states that it’s normal for temporary storage to consume 5 percent or less of total disk storage, so if your temporary storage utilization is under that number, don’t worry. However, if your system was gobbling up 12.75 percent usage of disk space like this one, you might want to do something about the situation. To determine which jobs are consuming temporary disk space, run the following Work with System Activity (WRKSYSACT) command to list your partition’s active jobs by the amount of net storage being used.
This displays your partition’s active jobs according to how much net storage (allocated storage less deallocated storage) each job is currently using. From the initial Work with System Activity screen, press the F11 key (switch view) three times to get to the storage view screen, which looks like this.
Although it’s not obvious, this screen displays all the active system jobs by net allocated storage. The screen doesn’t show net allocated storage for each job, but you can easily calculate it by subtracting the Storage→Deallocated number from the Storage→Allocated number for each job. Understand however that WRKSYSACT only shows data for jobs that have had activity since the last data collection. There may be other system jobs taking up temporary storage that weren’t active when you ran WRKSYSACT. Those jobs won’t show up in the display until they show some activity.
If you notice any jobs that are taking up too much net storage, end and restart those jobs to see if that affects your temporary and total disk storage utilization numbers. If that doesn’t help, you can take other measures, including IPLing the system. To help troubleshoot problems with allocating excessive temporary storage on your system, IBM offers a few other ideas in Technical Software Document 22152301, Temporary Space Growth Problem Debug.