Self-Documenting Systems (Actually Coupling Facilities) – One Year On

(Originally posted 2012-11-17.)

About a year ago I posted: A Small Step For RMF, A Giant Leap For Self-Documenting Systems.

A year on I’ve encountered some customer data that’s made me go "huh?", related to this.

In the referenced post I mentioned R744FLPN, the Coupling Facility’s LPAR Number. For the first time I’ve seen data where the match – with SMF 70 Logical Partition Number (in Logical Partition Section) – doesn’t work.

But that’s because I misinterpreted R744FLPN: It’s actually the User Partition Identifier. The difference, as I understand it is that Logical Partition Number can vary over time, as reconfiguration happens. Whereas the User Partition Identifier can be set and remain the same forever.(And apparently you need that for the CFRM Policy to work.)

Obviously I’ve fixed up my code – to use the User Partition ID in SMF 70 (again in the Logical Partition Section). And it’s yielded an additional set of detail in my code that describes the LPARs on a machine. (Deciding whether to kick myself is “a dish best served cold”. 🙂

So it’ll be interesting to see how people use User Partition ID (UPI). If you’re using it perhaps you could let me know the scenario where you’re finding it useful. And remember UPI is not just for Coupling Facility LPARs.

Another new aspect of self-documenting coupling facilities is described in System zEC12 CFLEVEL 18 RMF Instrumentation Improvements. That is all about how CF links are getting better documented.

(And if you were wondering why I haven’t blogged for a month it’s because I’ve been extremely busy with customer engagements and speaking at the UKCMG 1-Day Meeting and GSE Annual Conference (both of which were thoroughly enjoyable). I’m beginning another big study – and this post is the result of the first thing I tripped over in their data.)