Category Archives: Uncategorized

When Good Service Definitions Turn Bad

I was about to comment it’s been a while since I wrote about WLM but, in researching for this post, I discover it isn’t. The last post was WLM-Managed Initiators And zIIP. I seem to be telling a lot of customers their WLM service definition really needs some maintenance. In fact it’s every customer I’veContinue reading “When Good Service Definitions Turn Bad”

Heading Back Into Db2- Architecture Part 1

I loftily talk about “architecture” a lot. What I’m really getting at is gleaning an understanding of an installation’s components – hardware and software – and some appreciation of what they’re for, as well as how they behave. When I started doing Performance and Capacity – many years ago – I was less sensitive toContinue reading “Heading Back Into Db2- Architecture Part 1”

Coupling Facility Structure Versions

When I see an 8-byte field in a record I think of three possibilities, but I’m prepared to discover the field in question is none of them. The three prime possibilities are: A character field A 64-bit counter A STCK value An interesting case occurs in SMF 74 Subtype 4: Two similar fields – R744SVERContinue reading “Coupling Facility Structure Versions”

Mainframe Performance Topics Podcast Episode 31 “Take It To The Macs”

This is the first blog post I’ve written on my new work MacBook Pro. While it’s been a lot of work moving over it’s a better place as it’s an Apple Silicon M1 Max machine with lots of memory and disk space. That’s nice, but what’s the relevance to podcasting? Well, it’s very warm hereContinue reading “Mainframe Performance Topics Podcast Episode 31 “Take It To The Macs””

WLM-Managed Initiators And zIIP

One item in the z/OS 2.5 announcement caught my eye. Now 2.5 is becoming more prevalent it’s worth talking about it. It is zIIP and WLM-Managed Initiators. WLM-Managed Initiators The purpose of WLM-Managed Initiators is to balance system conditions against batch job initiation needs: Start too many initiators and you can cause CPU thrashing. StartContinue reading “WLM-Managed Initiators And zIIP”

Engineering – Part Six – Defined Capacity Capping Considered Harmful?

For quite a while now I’ve been able to do useful CPU analysis down at the individual logical processor level. In fact this post follows on from Engineering – Part Five – z14 IOPs – at a discreet distance. I can’t believe I haven’t written about Defined Capacity Capping before – but apparently I haven’t.Continue reading “Engineering – Part Six – Defined Capacity Capping Considered Harmful?”

Mainframe Performance Topics Podcast Episode 30 “Choices Choices”

It’s been a mighty long time since Marna and I got a podcast episode out – and actually we started planning this episode long ago. It’s finding good times to record that does it to us, as planning can be a bit more asynchronous. Hopefully this delay has enabled some of you to catch upContinue reading “Mainframe Performance Topics Podcast Episode 30 “Choices Choices””

Third Time’s The Charm For SRB – Or Is it?

Passing reference to Blondes Have More Fun – Or Do They?. Yeah, I know, it’s a tortuous link. 🙂 And, nah, I never did own that album. 🙂 I first wrote about System Recovery Boost (SRB) and Recovery Process Boost (RPB) in SRB And SMF. Let me quote one passage from it: It should alsoContinue reading “Third Time’s The Charm For SRB – Or Is it?”