I have tried VTS and 3592 tapes with no improvements seen.
-----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@bama.ua.edu] On Behalf Of Dave Barry Sent: Friday, October 14, 2011 6:40 PM To: IBM-MAIN@bama.ua.edu Subject: Re: LBI Performance? Real tape drives like D/T 3590 or virtual? I think hardware support is needed. db -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@bama.ua.edu] On Behalf Of Mingee, David Sent: Monday, October 10, 2011 1:50 PM To: IBM-MAIN@bama.ua.edu Subject: Re: LBI Performance? -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@bama.ua.edu] On Behalf Of Mike Schwab Sent: Monday, October 10, 2011 12:01 AM To: IBM-MAIN@bama.ua.edu Subject: Re: LBI Performance? Do you have both jobs? No, I would have to run the job again - once for each blksize How did the elapsed time compare? 35 min for each run. How about the number of blocks? 188,700 for 256k and 1,507,310 for 32k. the correct number of vts tapes in and out is 29 vols. (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 ---------------------------------------------------------------------- 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 ---------------------------------------------------------------------- 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 ---------------------------------------------------------------------- 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
