Author Archives: Martin Packer

(Originally posted 2007-01-31.) I suggested (in z/OS Release 8 Real Storage Manager SMF Record Changes) that I might talk about the changes to RSM in z/OS Release 8. As the release has been out now for about 4 months some of you might actually be on the brink of putting it into production. 🙂 Seriously,Continue reading “z/OS Release 8 Real Storage Changes”

(Originally posted 2007-01-26.) I presented to the Large Systems GSE meeting in Dudley on Wednesday on “DB2 Data Sharing Performance For Beginners” and an interesting question came up… “At what distance does performance begin to suffer when moving machines in a parallel sysplex apart?” As it happens I am dealing with exactly that question inContinue reading “Going The Distance”

(Originally posted 2006-12-13.) I’ve just been looking at some fascinating SMF 70 records. They come from a System z9 EC S54 machine and the LPAR they’re from is running z/OS Release 8. I say “fascinating” because: I’ve not seen an S54’s data before. (This is the largest z9 machine – with all 4 processor booksContinue reading “z/OS Release 8 CPU SMF Record Changes”

(Originally posted 2006-11-30.) In z/OS Release 8 Real Storage Manager (RSM) implemented brand new algorithms. One of the more significant changes was the adoption of a “new style” UIC value. This behaves much more like the old Expanded Storage Migration Age. Accordingly the old UIC value (SMF71ACA) isn’t really appropriate to use anymore. Or atContinue reading “z/OS Release 8 Real Storage Manager SMF Record Changes”

(Originally posted 2006-11-22.) In Mainframe v-Business Boas Betzler threw out a challenge: “Demonstrate SecondLife talking to CICS”. I’ve picked this up on behalf of IBM. Now, why on earth would you want to do that, Martin? To get beyond the “because it’s fun” answer (which is also true) let me tell you my view onContinue reading “CICS and SecondLife”

(Originally posted 2006-11-08.) Well, I don’t know about that. Maybe this contribution to the debate won’t add much. But there must be at least one performance person out there who hasn’t heard of the discussion around RMPTTOM. But would I want such a person amongst my readership? 🙂 I’m not going to rehearse the wholeContinue reading “Better Late Then Never – RMPTTOM”

(Originally posted 2006-05-22.) Here are a couple more SQL processing APARs. APAR PK22814 for Version 8 ESTIMATED SUBQUERY COST IS TOO HIGH WITH SORT MERGE JOIN. The APAR text says Correlated subquery cost is over-estimated for sort merge join. A well-performing sort merge join plan might not be chosen by DB2. Correlated subquery cost canContinue reading “2 More DB2 Access Path APARS”

(Originally posted 2006-05-15.) DB2 Version 8 introduced some very significant exploitation of 64-bit virtual storage. It would be naive to believe that was a total conversion to 64-bit and indeed installations’ mileage varies, depending on circumstances. Here are two APARs that show the journey continues… PK21268 MOVE CURRENT PATH STORAGE OUT OF STACK AND INTOContinue reading “DB2 Virtual Storage – The Journey Continues”

(Originally posted 2006-05-13.) (Scroll down if you’re not interested in DB2) This past week I’ve been updating our SQL Analysis code to cope with Unicode SQL statements. (If you bind a package or plan once you’ve gone to DB2 Version 8 New Function Mode the statement text is stored in the Catalog in Unicode.) TheseContinue reading “ASCII to EBCDIC Conversion with DFSORT”

(Originally posted 2006-05-06.) Nope, I’m not going to do a Rumsfeld. 🙂 But there are a couple of things I didn’t know (I didn’t know) about DFSORT. Relating them to you is probably OK because It’s not something I’m embarrassed about.:-) If you want to understand some of the funkier new DFSORT tricks you probablyContinue reading “Unknown Unknowns”