tag:blogger.com,1999:blog-4516533711330247058.post203452223069575507..comments2024-03-28T00:10:23.672-07:00Comments on Robert's Db2 blog: Db2 12 for z/OS - Let's Talk About MAXDBAT in ZPARMRoberthttp://www.blogger.com/profile/02058625981006623480noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-4516533711330247058.post-82856720214774727602024-01-18T18:52:41.643-08:002024-01-18T18:52:41.643-08:00This can be a little tricky. A Db2 monitor account...This can be a little tricky. A Db2 monitor accounting report doesn’t provide a “high water mark for DBATs used” figure. It will show you, at whatever aggregation level you’ve chosen (e.g., at the primary auth ID level), things like number of commits (basically, that’s the number of transactions) and average class 1 elapsed time (average transaction duration), and with those items of information you might be able to make inferences as to which DDF-using applications probably used the largest numbers of DBATs at one time.<br /><br />Another thought: via the Db2 for z/OS profile tables, you can specify warning thresholds for DBAT usage for different DDF applications – Db2 would issue messages when these thresholds are crossed, and with some tries and adjustments you might be able to see which DDF-using apps are really going high on concurrent DBAT usage.<br /><br />The IBM product Db2 AI for z/OS has, I believe, the ability to show high-water-mark DBAT usage at the auth ID and/or IP address (of app server) level.<br /><br />If, when MAXDBAT was hit for this subsystem, the general-purpose engines of the z/OS LPAR were not overly busy (i.e., if average MVS busy for those engines, per an RMF CPU Activity report for the LPAR, was less than 80%), consider raising your MAXDBAT value (maybe from 400 to 450 or 500) – that would allow more in-flight DDF transactions at one time, but you would have verified that the system has the processing capacity to handle that situation. If, on the other hand, the z/OS LPAR’s general-purpose engines were really busy at the time you hit MAXDBAT (e.g., if average MVS busy for those engines was over 90%), you might want to add processing capacity for the LPAR before taking MAXDBAT to a higher level.<br /><br />Also, note that the use of high-performance DBATs can lead to more DBATs being in an in-use state at one time, as explained in the blog entry at https://robertsdb2blog.blogspot.com/2013/12/db2-for-zos-want-to-use-high.html. Implementing hi-perf DBAT functionality often necessitates an increase in a Db2 subsystem’s MAXDBAT value.<br /><br />RobertRoberthttps://www.blogger.com/profile/02058625981006623480noreply@blogger.comtag:blogger.com,1999:blog-4516533711330247058.post-70244229215297271232024-01-18T15:49:54.862-08:002024-01-18T15:49:54.862-08:00I do use OMEGAMON. I have all the accounting load...I do use OMEGAMON. I have all the accounting loaded into a perf db table of DB2PMFACCT_GENERAL. And for the time period in question... I cannot find any DBAT thread history. Am I looking wrong?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-4516533711330247058.post-67330901300082534152024-01-17T20:12:23.451-08:002024-01-17T20:12:23.451-08:00You could use your Db2 monitor (IBM's is calle...You could use your Db2 monitor (IBM's is called OMEGAMON Performance Expert for Db2 on z/OS) to generate an accounting long report for the time period of interest. In doing that, you can tell your Db2 monitor to include in the report only activity related to the DRDA connection type - that way you'll only be looking at activity associated with DDF-using applications.<br /><br />RobertRoberthttps://www.blogger.com/profile/02058625981006623480noreply@blogger.comtag:blogger.com,1999:blog-4516533711330247058.post-14976327464968366722024-01-17T15:30:18.667-08:002024-01-17T15:30:18.667-08:00I am now thinking... when you retroactively realiz...I am now thinking... when you retroactively realize MAXDBAT was reached (by review system statistics)... how can one effectively review the accounting history for that moment in time to confirm the applications running at that moment??? This would help confirm which application contributed the most to using all those DBATs...Anonymousnoreply@blogger.com