I was fortunate enough to spend last week in IBM’s Silicon Valley Lab (SVL), both in formal sessions and talking to developers. One topic - which isn’t really all that new - is DB2’s REST support, which is pretty comprehensive and good. The basic idea with this support is you can call DB2 via a URI 1 , with a JSON payload, and get JSON back. It’s possible that only one acronym means anything to... [More]
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“What is this DB2 subsystem for?” is an important question - at least to me. And explaining this topic over lunch to a friend of mine who was a DB2 developer, convinced me it has more general importance. If you’re a DB2 sysprog or DB2 the answer is probably well known to you 1 . If you’re not a DB2 person it’s probably not so obvious. Something worth noting at this... [More]
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So now I get to sit and relax for umpteen hours, while a 787 speeds me to California. So I can write something. And, yes, it’s been a while. To tell you the truth, I’ve been working on back-to-back engagements and enjoying vacation for what seems like forever. And after a stint of that I generally I end up with a swirl of “if only I had time to write about that” topics in my brain. So... [More]
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In my “Parallel Sysplex Performance Topics” presentation I have some slides on Coupling Facility Processor Busy. I’ve worried about including them, considering them borderline boring. 1 In my head I justified them because they: Help people understand Structure Execution Time (R744SETM). Help people see the changed behaviour with Thin Interrupts. For both of those topics... [More]
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I was in two minds whether to do this as a screencast or a blog post. Obviously I plumped for the latter. There are a few reasons why: This is not terribly visual, there being only one graph. It’ll reach a wider audience, and the message is quite important. I’m feeling lazy. Anyway, here we are and I think this is quite an important subject - so I’m glad you’re here.... [More]
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For once this isn’t a blog post that discusses a podcast episode or a screencast. It is one where I feel a little exposed, but only a little. 1 I just updated my “Even More Fun With DDF” presentation - after a whole two months. You’d think there’d be little new to say after only two months, but you’d be wrong. Quite apart from some other additions, there is a... [More]
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Hot on the heels of Screencast 11 - DDF Spikes is my latest screencast: Screencast 12 - Get WLM Set Up Right For DB2 . In it I talk about the important topic of ensuring DB2 is protected against shortages of CPU (and zIIP). There are a couple of quite nice examples to illustrate the point. I should note that I don’t see instrumentation that explicitly shows what happens when IRLM gets heavy... [More]
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It’s been a busy few weeks but we’ve a new episode out. The experiment with narrowing the “stereoscape” was an interesting one. It is always going to be effort to do this, but having edited all 5 segments I got quite good at it. I think I maybe narrowed it a little too much, but I’d be interested in how it sounds to y’all. To my ears Marna and I (and indeed our... [More]
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It’s been a month since I last did a screencast - and boy what a busy month I’ve had. And in that month I had the privilege of working with a very nice customer, exercising my DDF Analysis code. 1 As so often happens, a graph or two come together to tell a nice story. One I shared with the customer, and one I’m sharing with you. Because graphs are involved the natural medium for... [More]
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So this is a shorter episode, much to Marna’s pleasure. (Personally I’m indifferent to show length, regularly listening to episodes of other podcasts that run to 1.5 to 2 hours.) It was very good to have a guest: Barry Lichtenstein. (I kept in the bit where I mispronounced his name, as I thought it a funny mistake [1] . You’ll find another piece of flubbing, again because it was... [More]
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If a customer has Transaction goals [1] - for CICS or IMS - it’s possible to observe the CPU per transaction with RMF. But you have to have: Transaction rate CPU consumed on behalf of the transactions. This might seem like stating the obvious but it’s worth thinking about: The transaction rate and the CPU consumption have to be for the same work. Now, a Transaction service class... [More]
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I’m writing this under a lovely cherry tree in my back garden, in cool shade on a warm summer’s day. Before you complain “that ain’t working” I’ll just point out this is on a Saturday afternoon. And the “air cooling” is what makes this post possible. Just this past week I began an experiment. As with all experiments I might continue with it, but I... [More]
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Boy has this one been a “slow train coming” but I’m glad it’s out now. And it was fun making it. Especially the piece with Frank and Jeff. It’s a long listen; As always I’m comfortable with long podcast episodes. Enjoy! Episode 14 “In The Long Run” Show Notes Here are the show notes for Episode 14 “In the Long Run”. The show is called... [More]
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Back in 2009 I wrote about Performance of the (then new) DFSORT JOIN function . This post is just a few notes on things that might make life easier when developing a JOIN application. Specifically the one I alluded to in Happy Days Are Here Again? when I talked about processing SMF 101 (DB2 Accounting Trace) records. And I wrote it having scratched my head for a few hours developing a JOIN... [More]
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I’ve written a lot about DDF and SMF 101 (Accounting Trace) over the years. It turns out my code went backwards a few years ago, and with good reason. Let me explain. But before I do, recall “my code” refers to a DFSORT E15 exit that “flattens” SMF 101 records, extracting the DDF-related fields into fixed positions. Each input record leads to an output record (if it... [More]
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This post follows on from Some Parallel Sysplex Questions, Part 1 - Coupling Facility . Again it’s a high level treatment. In contrast to Coupling Facility (CF), there is really only one type of resource: Signaling paths. But again application componentry is what brings it all to life. In this case it’s XCF groups and members. And the motivation for all this? Responsiveness and (CPU)... [More]
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In Some WLM Questions I outlined my approach to looking at WLM implementations.
It was necessarily very high level, but the intention was twofold: To prime customers about the kinds of questions I might be discussing with them - if I ever saw their data. [1] To give anyone maintaining a WLM policy some structure. It remains my view that WLM needs care and feeding, on a not-infrequent basis. You... [More]
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Long ago I added reporting on DB2 log writing to our code. At the time it was just to understand if a particular job or transaction was “log heavy”. That is, I was interested in the job’s perspective, and whether it was dependent on a high-bandwidth DB2 logging subsystem. A recent incident, however, gave me a different reason to look at this data: We were concerned with what was... [More]
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I’m starting to write this on a train to London. (Not Paris.) [1] When I get there I’m going to present the “New Improved” “Even More Fun With DDF” pitch to the UK GSE zCMPA user group. I was done with the slides a few days ago - or so I thought. [2] Well, I got some “down time” earlier this week to work on my DDF code some more - which resulted in... [More]
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It’s been a few weeks since we last recorded and it was good to get back in “the studio” again. As usual it’s quite a wide range of topics. We hope you enjoy them. Two technical notes: I have new headphones which reduced the amount of bleed through from my ears to the microphone. Not entirely perfect but better. I still have to go through a fair amount of clean up, which... [More]
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