Category Archives: Case study

share how to use one or several performance tools to trouble-shooting a real performance issue

Case Study: over 99.99% SQL performance improvement

In this post, I would go through a case where I identified a solution to a SQL statement whose performance was perceived as good/normal. My solution made an over 99.99% improvement on time needed to execute the SQL via table reorganization. Index rebuild/table reorg is not always making noticeable performance improvement for related SQL most…

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Case Study – Use ST04 SQL Stats history in Performance analysis

This post covers how I used SQL historical stats from SAP ST04 in analyzing a true performance incident related to SAP system cloud migration. I used SQL stats from “good” and “bad” periods and compare the stats and found where the problem was. This led to resolution of performance issue. You can refer to my…

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Many SAP work processes were left in “on hold” status with RFC info

I was contacted on one production issue – Almost all SAP background work processes were in “on-hold” status with RFC info in SAP SM50 work process monitor transaction and seemed like not moving. I was asked why? Please continue reading to understand the reason which I identified through analysis via transaction SM50, STAD, RZ12. This…

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Mass VS Individual deletion – Does it matter to SAP program performance?

My previous post – “SAP ST12 Trace – SQL performance analysis” mentions that we can use mass/array database operation to replace many individual execution of the same SQL to improve database access performance. This blog will go through a true business case where a code has been changed to use array/mass SQL deletion to replace…

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Why would SAP job runtime suddenly jump well above normal range?

Business was complaining that runtime of a periodic SAP background job was suddenly jumped in production environment. There is no code change and no volume change and other jobs and transactions are running well. They were asking why this happened. I was consulted and looked into the situation. Finding the issue was related to Oracle…

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SAP migration and performance – Would use of SAP MDS migration tool impact application performance?

My customer needs to migrate their regional ECC systems from Unix-based systems to Linux-based system. Some of regional systems are very big and their database sizes are over 10 Terabytes. To reduce system down time and mitigate risks of system migration cutover, the customer decided to use SAP’s Minimized Downtime Service (MDS) to migrate those…

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SAP System Log Review – SAP Terminal in status Disc

Recently I was involved in reducing SAP SM21 system log. One of top messages in our SAP SM21 log is “Terminal ##### in status DISC” & “Delete session ### after error ###”. About 20 such messages were generated hourly under a particular user. I looked into this and fixed the issue. I also looked into…

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SAP Performance issue from SAP server upgrading

There were performance issues in production system– longer runtime of several business transactions and Server overutilization after SAP application servers were upgraded even the upgraded system has higher capacity measured in SAPS and new servers are faster. Testing done in investigation shows that a flaw/limitation in SAP system (SAP kernel) is the culprit. The flaw/limitation…

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