Do you have both jobs? How did the elapsed time compare? How about the number of blocks?
(I would expect slightly more than 1/4 as many blocks on the first 19 large block tapes vs small block tapes, and a lot less blocks on the 20th large block tape since more data should have been stored on the large block tapes.) On Sun, Oct 9, 2011 at 10:30 PM, Mingee, David <david.min...@libertymutual.com> wrote: > Hello All, > Anyone had success with performance gains in run time and fewer > tapes being created when using z/OS Large Block Interface(LBI)? We are on > R1.11 and have created tapes with blksize of 256k(262144) and the block count > is reduced by a factor of 8, but we do not see any improvements in elapsed > time or fewer tapes being created(20 output tapes at 32k and 20 output tapes > at 256k). Am I missing something? IBM documentation states: > > Taking advantage of LBI: You can improve the performance of tape data sets by > using the large block interface (LBI) for large block sizes. When the LBI is > available, the COBOL run time automatically uses this facility for those tape > files for which you use system-determined block size. LBI is also used for > those files for which you explicitly define a block size in JCL or a BLOCK > CONTAINS clause. Use of the LBI allows block sizes to exceed 32760 if the > tape device supports it. > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO > Search the archives at http://bama.ua.edu/archives/ibm-main.html > -- Mike A Schwab, Springfield IL USA Where do Forest Rangers go to get away from it all? ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
