Learn from my mistakes – Which Engines Does IRD Vary Offline?

(Originally posted 2005-06-13.) I’d made the assumption (in my code) that IRD would vary offline the top logical engines when it decided to vary an LPAR’s logical engine offline. In fact that isn’t the case. I have data from a US company where it’s engines 2 and 3 (out of the range 0-11) that tendContinue reading “Learn from my mistakes – Which Engines Does IRD Vary Offline?”

DB2 Accounting Trace Parallel Task Rollup – A Problem Child?

(Originally posted 2005-05-09.) Here’s another breakage of Accounting Trace that’s been fixed: APAR PK03905 describes a problem with DB2 Parallel Task Rollup that causes the Group Buffer Pool Accounting data for GBP 0 to be missing. (Its title talks about IFCID 148 but in the detail IFCID 3 is roped in. IFCID 3 means “AccountingContinue reading “DB2 Accounting Trace Parallel Task Rollup – A Problem Child?”

Of interest to performance people in DB2 Stored Procedures environments

(Originally posted 2005-05-04.) I just saw the following APAR close. PQ99525 fixes a couple of problems for “nested” DB2 access i.e stored procedures, triggers and user-defined functions (UDFs). For anyone thinking “this is not my shop” I think you should consider that these functions are appearing in many modern applications and your Applications people probablyContinue reading “Of interest to performance people in DB2 Stored Procedures environments”

ESCON vs FICON and LPAR IDs

(Originally posted 2005-05-03.) My thanks to Greg Dyck for pointing out the following on IBM-MAIN: “The Store-CPU-Identifier now allows for a 8 bit partition identifier but the ESCON I/O protocols only allow for a 4 bit identifier. This is the reason that multiple channel subsystems must be implemented if you want more than 15 partitionsContinue reading “ESCON vs FICON and LPAR IDs”

LLA and Measuring its use of VLF

(Originally posted 2005-04-28.) I’m reminded by a question on MXG-L Listserver that many people don’t understand how LLA works – and in particular how to interpret the statistics in VLF’s SMF 41 Subtype 3 record. You really have to understand the exploiter to make sense of the statistics. Here’s how it applies to LLA… LLAContinue reading “LLA and Measuring its use of VLF”

Coupling Facility Capacity Planning

(Originally posted 2005-04-26.) A friend of mine from the ITSO in Poughkeepsie is contemplating a Red Paper on Coupling Facility Capacity Planning. I think this is a splendid idea – and would be willing to contribute myself. But I’m wondering what y’all think of the idea. And of what you’d like to see in suchContinue reading “Coupling Facility Capacity Planning”

Innsbruck z/OS and Storage Conference – Day 4

(Originally posted 2005-04-14.) Session TSP11: Performance of the TotalStorage DS8000, Speaker: Lee La Frese Of course a new disk controller from IBM is going to appear awesome. 🙂 DS8000 is no exception. Currently 2-way and 4-way POWER5 processors. Statement of Direction for an 8-way machine. POWER5 can go up to a 64-way. I/O access densityContinue reading “Innsbruck z/OS and Storage Conference – Day 4”

Innsbruck z/OS and Storage Conference – Day 3

(Originally posted 2005-04-13.) Session ZP05: Parallel Sysplex Tuning, Presenter: Joan Kelley Joan gave a good summary of CF levels and general-but-detailed tuning recommendations. Enhanced Patch Apply on z890 and z990 allows different CF levels on the same CEC. But a customer suggested that in their environment re-IPLing one of the CF LPARs brought it automaticallyContinue reading “Innsbruck z/OS and Storage Conference – Day 3”