Satid Singkorapoom
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Guru: IBM i Experience Sharing, Case 5 – Using IBM i PDI Charts To Answer Performance Questions
July 18, 2022 Satid Singkorapoom
During my long career as an IBM i performance specialist, it was natural for people to ask me performance-related questions of various kinds. But in many cases, it seemed to me that the customer could not understand my answers, and I could not provide supporting evidence due to the lack of a performance reporting tool that could produce easy-to-understand explanatory information. The situation changed for the better with the availability of IBM i Performance Data Investigator (PDI) tool as of release 6.1. I would say that the PDI tool provides charts of information that resemble those used by business people …
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Guru: IBM i Experience Sharing Case 4 – Investigating Time-Sensitive Transaction Issues
June 6, 2022 Satid Singkorapoom
Among the central processing hardware resources in a computer system – CPU, GPU, memory, disk, PCI-Express I/O bus – disk has always been the slowest component. Even the latest flash disk or NVM-Express flash drive or card is slowest, but not by much. Back in the days of hard disk, disk I/O was the most popular cause of performance problems. From experience, I always looked at it first in my investigation.
The modern SAN flash disk can still be the performance bottleneck when it is not deployed properly, as I shared in Guru: IBM i Experience Sharing, Case 3 – …
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Guru: IBM i Experience Sharing, Case 3 – When Performance Issues Come From Without
April 4, 2022 Satid Singkorapoom
When I started my IT career 35 years ago, it was in the “centralized” universe that originated from the mainframe model. All core application codes ran in one — and only one — big iron that all users accessed with “dumb” terminals devoid of any GUI. Problem solving in AS/400 systems was frequently straightforward and not time consuming because most cases were anything but elusive.
But the contemporary IT infrastructure universe has evolved into a big onion, with layers that we must peel while troubleshooting. I often find myself having to address a problem in multiple layers, and it no …
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Guru: IBM i Experience Sharing, Case 2 – Dealing With CPU Queuing Wait Time
March 21, 2022 Satid Singkorapoom
When we drive our cars, we hope to avoid red lights and traffic jams, because we all hate waiting immobile in traffic. I’m sure that you are aware, fully or subtly, that active jobs in any computer system can encounter wait as well. The IBM i developer team has categorized many types of wait.
In this article, let’s look at CPU Queuing wait time. Let’s see how we can interpret and address it in a sensible way to resolve poor performance. I’ll try to provide you with a useful approach to wait time analysis using a gloriously useful performance reporting …
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Guru: IBM i Experience Sharing, Case 1 – Object Authority Check And Batch Job Performance
March 7, 2022 Satid Singkorapoom
Batch processes are perennial in virtually all kinds of business processing. From time to time, customers have to deal with batch runs that take too long, and many factors influence run time. One such factor in IBM i is how you assign object authority access rights for user profiles to the libraries and objects that are accessed by batch jobs. The importance of this factor can be found in the following case study.
Many years ago, a customer asked me to determine why batch run time took too long. The customer ran 25 concurrent batch jobs in the batch process …
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