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All posts
Why Do We Keep Building Bigger Machines?
I know of no customer who uses the full capacity of a zEC12, let alone a z13? 1 So why do we make them bigger each time? I should state this post is not in support of any product announcement; It’s just scratching an itch of mine. I think it’s an interesting topic; I hope you agree. What Is Bigger?
While this post isn’t exhaustive I think the main aspects are:... [More]
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A Record Of Sorts
When looking at a batch job 1 I like to see how the data flows through the various steps. The first step - some 23 years ago - was to look at the Life Of A Data Set (“LOADS” for short). 2 With LOADS - for VSAM and non-VSAM data sets - you can see who reads and writes the data set. You can also see the EXCP count. More on that in a bit but suffice it to say EXCP count might be enough to... [More]
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Fearful Symmetry
The title of this post is a Physics reference but this is not about Physics. 1 A customer asked me the question “why am I not getting balanced CPU Utilisation between the various machines”? I’m responding without data at this stage so I’m going to be even more “hand wavy” than usual - both in the long call I had with them and this post. So, let’s take it... [More]
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Corroboration Not Correlation
This is a post where I have, yet again, to be careful to obfuscate the customer’s situation; I’ve no wish to embarrass them.
So you’ll forgive me if there are no numbers.
But there is a lesson worth sharing here.
So I’m going for it… It’s about DB2 and Workload Manager. 1 I was recently asked to explain why an application’s DB2 Accounting Trace was... [More]
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Mainframe Performance Topics Podcast Episode 5 "The Long Road Back From Munich"
(Reposted without change as I accidentally deleted it while getting rid of a SPAM comment.) Episode 5 had a different feel for me.
It was our first “trip report” episode, and it felt much looser for that. In fact the sound effects between topics could’ve been elided but for now I’m sticking slavishly to the format.
It didn’t feel too artificial to me. I’m... [More]
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Mainframe Performance Topics Podcast Episode 6 "Expect The Unexpected"
Episode 6 was a complete surprise to us! Marna had thought I was on vacation a week earlier than I was. To be fair, I expected to be with a customer in Australia that week. But then the workshop got pushed back and so this week came free [1] So we went “why not?” and so this episode was born. It is of course largely built around this blog post but we had a couple of other things we... [More]
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What Do I Know?
Or “ The Man Who Knew Too Little ”? This post is occasioned by a number of things coming together, the most recent of which is reviewing a very nice upcoming RedPaper. The gist is this:
You’re responsible for managing Performance, Capacity and (to some extent) mainframe costs.
But you can’t rely on anybody to tell you anything. A bit pessimistic, perhaps a little... [More]
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Engineering
Pardon the bad pun. Perhaps I should’ve written “Engine-ering” but where exactly do you put the dash? [1] There were hints on this topic in Born With A Measuring Spoon In Its Mouth but the real motivation came from a z196 customer without Hiperdispatch enabled. But what on earth am I on about? OK, here we go: Generally our [2] code doesn’t report down to the single engine... [More]
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Born With A Measuring Spoon In Its Mouth
SMT really was born with a measuring spoon in its mouth. [1] Let me rewind a few years… So, when SMT (Simultaneous Multithreading) was being designed I was privileged to be on the periphery of discussions about how to instrument SMT.
Things like CPU Utilisation get a little wierd in the SMT case, as you can imagine. Now, I was only on the periphery of the discussions and they carried on... [More]
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Mainframe Performance Topics Podcast Episode 4 "The Road To Munich"
Episode 4 was, of course, our fifth podcast episode. I had a lot of fun making the intro - with Audacity.
I’m not sure if it’s “lost souls” or “tuning in”.
It was meant to be the latter but the former is also good. Below are the show notes. The series is here . Episode 4 is here . Episode 4 “The Road To Munich” Show Notes Here are the show notes... [More]
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Shared Coupling Facility CPU And DYNDISP
You probably don’t have the same problem I do, namely not having access to SMF data from all the systems in your mainframe estate. You’ll recognise that as a provocative statement if ever there was one;
For all sorts of reasons not every system’s RMF SMF is collected. Most notably, test systems often aren’t instrumented. This post is about Coupling Facility (CF) image... [More]
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Refactoring ISPF File Tailoring And DFSORT
On Twitter I joked ‘refactoring’ is ‘taking perfectly well working code and risking breaking it’.
This post describes one such exercise. tl;dr: It was well worth it! In DFSORT Tables I wrote about a technique to create tables (or grids) using IFTHEN. It’s been a maintenance headache to the extent that the “Principle” Of Sufficient Disgust kicked in.
So... [More]
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iThoughts The Legend
As I’ve indicated elsewhere we use iThoughts for outlining our podcast episodes (and use it to track completion). I’ve developed quite a nice technique for iThoughtsX (the macOS flavour), which I’ll share with you. This is in case you’re inclined to play with newer toys. Consider the following fragment of an outline: You’ll see some of the nodes are filled (arguably)... [More]
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More Fun With DDF
Already this year I’ve posted thrice on DDF: DB2 DDF Transaction Rates Without Tears DDF Batch DDF Counts It’s clearly something that’s important to me right now. So this post is to mention I’m putting the finishing touches to a new presentation (the third of the year so far). I’m giving it to European customers in Munich in mid June. I’m also giving it as an... [More]
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Mainframe Performance Topics Podcast Episode 3 "Getting Better"
You probably wonder why I post to my blog echoing our podcast episodes. There are two reasons: Yes, it alerts more people to our podcast series. Well duh. It gives me a chance to inject something more personal about the episode. So in the latter spirit I’d say the highlight for me of making Episode 3 was getting the “three part disharmony” working. Glenn Wilcock very kindly... [More]
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