The best time to use the performance management tools offered on the iSeries is before crisis erupts. More often than not performance management is something used only in crisis situations, when the system grinds to a halt and you need to determine the cause and remedy. And these tools are often left idle during the "normal" times when they could instead be used to create a more efficient system.
Included in OS/400
The three basic performance management tools -- WRKSYSSTS, WRKDSKSTS and WRKACTJOB -- are, of course, included in OS/400. Unfortunately, they are not always put to the best use at the best time. For example, I've watched plenty a good operator bang out WRKACTJOB on the keyboard at the least sign of trouble. While WRKACTJOB is very useful tool, indiscreet use of it can make an already bad situation worse.
In many cases, what is needed is a clear understanding of these tools and how they work. From there, we can development a strategy that will allow us to make the best use of them in good times and bad (i.e., during normal operations and when the system is hung).
Understanding what these tools do
Following is a brief description of what each tool does (the OS/400 command used to invoke each is provided in parentheses):
Work with Active Jobs (WRKACTJOB). This tool allows a user to collect performance data on jobs and programs running on the system. You can use it to track response times for interactive jobs in an effort to achieve sub-second response times. It is also useful for tracking disk I/O activity and CPU usage for both interactive and batch jobs.
Besides its common use of detecting which job, if any, is sucking up all the CPU and bringing the system to a halt, this tool also gives you a number of options you can run against the individual jobs it lists, such as holding jobs and working with individual jobs via the WRKJOB command.
Work with System Status (WRKSYSSTS). The Work with System Status tool is a two-part tool. The first part gives you a summary of the capacity of the basic resources available on your system and how much it is being used. It also allows you to track that information over a given period of time.
The second part of the Work with System Status tool is an interactive performance tuning device that lets you track the efficiency of your system and allows you to modify the allocation of certain system resources to improve this efficiency.
Work with Disk Status (WRKDSKSTS). This tool allows you to track different kinds of activity on the disk units in your system. This can give you valuable insight so you can maintain an equal distribution of activity among your disk units. And, with a little ingenuity, you can even determine how a data file is spread across disk units.
More to come
These are well-established tools, but you may be surprised how much more can be gained from them than you thought. In coming installments, we'll take a look at each of the tools in detail (See How to get the most from WRKACTJOB.) We'll explain how they interrelate and how to interpret and use all the various data they -- and other related tools -- provide. We'll also give you some tips to make them simpler to use.
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About the author: Ron Turull is editor of Inside Version 5. He has more than 20 years experience programming for and managing AS/400-iSeries systems.
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MORE INFORMATION
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- Three fun things you can do with WRKACTJOB
Sometimes it's the simple tools -- like OS/400's green-screen Work with Active Jobs (WRKACTJOB) -- that you take for granted. WRKACTJOB's a lot older than many readers on this list and -- because of that longevity -- it contains some useful features that can be handy in different situations. Joe Hertvik takes look at three fun things our old friend WRKACTJOB can do.
- Tuning the iSeries
Is there a simple way to tune up the iSeries? Site expert Tim Granatir says if interactive performance is your issue, then check the faulting rates in the various pools by using the WRKSYSSTS command.
- Checking for failed RAID arrays
Search400.com member Justin Haase shows you how to use the WRKDSKSTS command to quickly determine if you lost a drive over the weekend.
