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CICS VSAM Buffering
Four score and seven years ago (or so it seems) the Washington Systems Center published a set of mainframe Data-In-Memory studies. These were conducted by performance teams in various IBM labs and were quite instructive and inspiring. I wish I could find the form number (and a fortiori a PDF version) for this book. Anyone? Even hardcopy would be really nice. The reason I mention this is because... [More]
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Memory Metrics Now That z/OS Release 8 Is Upon Us
I was asked an interesting question today by a customer - one with dozens of LPARs and therefore not much time to study each one in excruciating detail... "Given that System High UIC (hereafter referred to as 'UIC') behaves differently in z/OS R.8 how should I treat it?" I've posted on this question in MXG-L Listserver, soliciting experiences and opinions. With z/OS R.8 we replaced the "page-UIC"... [More]
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Mor(e )on UIC
Thanks to the people who responded to this blog entry . And to the people who talked to me offline. The result is a slight shift in emphasis: I never did talk about UIC as the primary metric of memory constraint. If you read the referenced blog item I mentioned it as one of three, alongside paging rate and free frames. The shift is that I'm going to be more strident about UIC in future, relegating... [More]
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If The Cap Doesn't Fit...
... swear at it. :-) No, I KNOW that's not right - but it's (for me) an irresistibly bad pun. And it's a natural reaction, too. :-) In a recent customer situation I looked at the RMF Workload Activity Report data for a number of service classes. One WLM Sample count was particularly high: "Capped". In fact I look at, with tooling, SMF and the actual field is R723CCCA. (An IBM... [More]
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System z Expo, Las Vegas, 13-17 October
With a couple of working days to go before the deadline I've completed my two presentations for Expo. As usual I've added some new stuff, based on new technologies and some situations I've encountered. And rather than throwing older stuff out I've moved most of it to backup foils. While I'm prepared to present the backup material I don't expect to have time to in the sessions. But at least you'll... [More]
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Drawing The Line
You'd think it would be pretty simple to draw a line. Right? This post discusses an enhancement I'd like to make to my current reporting - and I'm pretty sure that technically I can do it. The question is whether I should . Consider my current "Memory by address space within Service Class" graph. Here's a sample: And here's what I think I might like it to look like: Obviously the line's... [More]
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Batch Capacity Planning, Part 2 - Memory
I can't believe it's been almost a week since I wrote Batch Capacity Planning, Part 1 - CPU . Where did the time go? Re-reading it I'm struck by the overwhelming theme of Batch's unpredictability and lumpiness. This is true of memory, as well, but to a much lesser degree. Why to a lesser degree? Well, in most systems I look at the memory usage is mostly fairly constant and dominated by big... [More]
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IMS Version 10 Memory Enhancements
Regular readers would know I'm working on my "Memory Matters in 2008" presentation, which is a re-spin of the '07 Version. One of the things I talk about is IMS. Thanks to my team mate Andy Wilkinson for this list of IMS Version 10 enhancements, all of which are virtual storage usage improvements. Here are the more important items: OTMA message flood protection (prevents LSQA filling). This is... [More]
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Flash Saviour Of The Universe?
When I first heard of Flash Express as part of the zEC12 announcement -
some time before announcement - I thought of one use case above all,
and one of particularly poignant resonance with some of my readers: Dump capture amelioration. Then, in the marketing materials, I heard of others.
And the discussions have grown more numerous recently.
So it’s time I expressed (pardon the pun) my... [More]
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IBM System z Technical University - Vienna, May 2-6
I'm working on my presentations for System z Technical University - Vienna, May 2-6 and I'm reviewing the agenda. As well as my four presentations there are lots of other goodies. These range from the Management level down to the purely technical. (I guess mine are towards the latter end of the scale - but I'd say there's lots of pressure on us all to work on cost so detailed information on e.g.... [More]
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Memory Breakdown in Firefox
A couple of years ago I was chatting to Firefox developers on IRC about the need for a memory map in the browser. I won't claim any credit at all for it happening. (In fact I don't know when it did get implemented.) If you want to figure out where the memory's going use about:memory . Here's a nice post showing where it proved invaluable to the developers: You make what you measure by Nicholas... [More]
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A Small Step For RMF, A Giant Leap For Self-Documenting Systems
I mentioned APAR OA21140 before - here . It's quite an old APAR and so it will (in all likelihood) be on your systems. I'd like to draw your attention to a subtle 1-byte field in the SMF 74 Subtype 4 (Coupling Facility Activity) record: R744FLPN. It's the partition number for the coupling facility. (If you've seen any one of several of my presentations I'll've talked about this field.) Here's... [More]
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My Slides Are Ready For Vienna
I wouldn't want you to decide not to come to Vienna , just because I've made my slides available on Slideshare: I'd hope you'd come to Vienna anyway. It's a great place and it's going to be a great conference. Lots of people can't make Vienna and I don't suppose having the slides to hand is going to tilt the playing field significantly away from coming if you weren't going to anyway. I don't... [More]
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New Blog Banner - In Honour Of The New zEnterprise EC12 (zEC12)
I hope you like my new blog banner - in honour of the new zEnterprise EC12. We actually announced the zEC12 (for short) the day I returned from vacation. Great planning, IBM! It's taken me a while to catch up - and changing the banner was an important step. I've known about the soon-to-be-announced processor range for quite some time, as I think you'd expect. And tracked what was going to be... [More]
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Capacity, Performance and Systems Investigation
At one level Performance and Capacity Management and Systems Investigation are clearly linked: They share the same data. Or much of it at least. But I think they're linked in another way, too. Over the past few years I've gradually shifted emphasis towards Systems Investigation. But this has only been a slight shift, a "non modo sed etiam" and still only really mainframe. So I'm... [More]
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DB2 9 Memory Requirements
Twice the "128GB" question has come up in newsgroups (the latest in DB2-L). This sort of thing freaks people out - so let me tell you what I know of the matter... I was fortunate to attend the T3 for DB2 9 in February. This question came up in the context of some changes to DDF : In Version 8 communication between DDF's DIST address space and the DBM1 address space was via CSA (actually ECSA so... [More]
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Memory Metrics - An Overdue Update
In 2007 I posted twice on memory metrics. The original posts are Memory Metrics Now That z/OS Release 8 Is Upon Us and Mor(e )on UIC I should probably have posted an update some time ago. In the latter I said "Obviously copious free frames would suggest no constraint." That's true but I would invite installations to consider something else... Capturing a dump into virtual memory backed... [More]
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System z Technical Conference - Dresden
Tomorrow I fly to Dresden for the annual European System z Technical Conference. It's at just the time of year when I can decide in my head that Spring has sprung and that Summer won't be long coming. :-) This is a great conference and I always enjoy attending it (and presenting at it). Talking of which, I have three sessions this year: Much Ado About CPU which has a fair modicum of new stuff,... [More]
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UK GSE Conference 30-31 October - Memory Matters in 2008
One of the problems with having a presentation with a topical title is that you keep having to update the darned thing. :-) "Memory Matters in 2007" is a case in point. It's morphed over the years from two presentations: "Central Storage Performance" and "Expanded Storage Performance" (the latter of which eventually became obsolete) to a presentation that covered OS/390 real memory, DFSORT and DB2... [More]
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