On Sun, 15 Mar 2009, Larry Burch wrote: > Is there an equivalent to DCB's BUFNO subparm when dealing with VSAM? > > I need to initialize (actually write real data into every record) several > fairly > large VSAM RRDS datasets; would like it to proceed a bit faster. > > And I realize I don't know what to say. I even actually tried with > BUFNO=200, > expecting no observable difference. That was also the result . > > Even if there is something that would not work on my OS390.210 system, I > would still like to know about it. > > Larry M. Burch lmburch [...@] cabq.gov 505-768-2948
One or both of BUFNI (for Index buffers - KSDS only) or BUNFD (for Data buffers) // AMP='AMORG,BUFNI=n,BUFND=m' replace "n" and "m" above with the proper values for your application. Please note that, depending on the application, increasing one or the other or both can actually DECREASE efficiency and INCREASE run time! Know what you're doing in the application! Case in point: Program used LSR buffering and had a huge BUFND. However, most of the direct retrievals were for keys which did not exist in the file (weird, I know). This caused LSR to read in BUFND records on every GET, then immediately invalidate those buffers due to "record not found". This was in a loop where 90%+ of the keys were "not found". This was a huge I/O load. The program ran for over 10 hours (as I recall). I looked at the program and rewrote it. The rewritten program ran in about 5 minutes (again, as I recall). No offense, but "modern" programmers are not very smart about old tyme techniques (anybody else remember the old sorted master and transaction files? That was this was, but done in a "modern" way that did not require any sorting. This despite the fact that the keys in VSAM are always "sorted" in ascending sequence anyway. My replacement was basically a "read each file and do a 'match merge' of the transaction with the master'". -- Q: What do theoretical physicists drink beer from? A: Ein Stein. Maranatha! John McKown ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
