Category Archives: Uncategorized

(Originally posted 2006-02-24.) My friend Frank Kyne in the ITSC Poughkeepsie center sent me a link to this draft RedPaper. It provides useful information, from some realistic benchmarks, on a number of Coupling Facility configuration options. I haven’t exactly been idle in this space recently: One of my favourite clients has sent me their DB2Continue reading “Useful RedPaper: Coupling Facility Performance: A Real World Perspective”

(Originally posted 2006-02-24.) APAR PK18018 documents a condition where the use of either the FETCH FIRST n ROWS or OPTIMISE FOR n ROWS clauses leads to a suboptimal access path. Occasionally you can get an ABEND. This APAR is marked for DB2 Version 8 only.

(Originally posted 2006-02-22.) APAR OA15323 documents the F CATALOG,REPORT,CATSTATS and F CATALOG,RESET,CATSTATS commands which became available with z/OS Release 7. The REPORT command will list I/O access statistics, as well as BUFNI, BUFND, and STRNO information for each catalog. To limit the command to just a single catalog there is a second format (using theContinue reading “Undocumented Catalog Address Space Command – CATSTATS”

(Originally posted 2006-02-22.) APAR OA14572 documents a problem where there is excessive SRB time and an increase in EXCPs for the index component of a VSAM KSDS accessed by RLS when two or more RPLs are adding records to the end of the data set.

(Originally posted 2006-02-22.) APAR PK15454 documents an extension to DB2’s EXPLAIN function which makes correlation of the various tables involved much easier. This enhancement is used by Visual Explain but can also be used by people querying the tables EXPLAIN produces, in particular DSN_FILTER_TABLE and DSN_PREDICAT_TABLE.</p. When you EXPLAIN a statement it produces rows inContinue reading “Enhancement For Users of DB2 EXPLAIN”

(Originally posted 2006-02-22.) I’m deeply involved in a nice complex study at one of my favourite clients at the moment – so I’ve just come up for air for half an hour or so. So I’m catching up on blogging about interesting APARs. So APAR PK15890 is my second SQL Access Path Enhancement of theContinue reading “SQL Access Path Enhancement – Second of the day”

(Originally posted 2006-02-22.) APAR OA14839 documents Omegamon support for 2107 (DS8000) devices.

(Originally posted 2006-02-22.) APARs OA14769 and OA14340 document changes to the SMF 30 record. Whether you call them enhancements or fixes depends on your perspective… APAR OA14769 is marked FIN which means no fix is immediately available, but one is expected some time in the next 24 months. SMF30MES should be set to ’02’x wheneverContinue reading “Two SMF Type 30 APARs”

(Originally posted 2006-02-22.) DFSMS APAR OA15034 documents a condition where some controllers support MIDAWs and other controllers don’t. Where a tablespace spans these two kinds of controllers this APAR is important. MIDAWs (Modified InDirect Access Words) are a new channel programming construct on System z9-109 processors which can improve the efficiency of FICON channel programsContinue reading “MIDAWs APAR – Mixed Control Units”