Was just talking about Dr. Artis with an old friend. He is teaching at Virginia Tech: https://www.aoe.vt.edu/people/advisory/pat-artis.html
I think Performance Associates is still around: http://perfassoc.com/ Charles -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Allan Staller Sent: Friday, May 19, 2017 11:59 AM To: [email protected] Subject: Re: SDB (system determined Blksize) IBM for many years supplied a macro or subroutine called TRKCALC that can be used for space calculations. I don't know if it's still around. GIYF. The actual formula used is: Physical records per track = 1729/(10+K+D) D= 9 + (DATALEN + (6x((DATALEN+6/232)) +6/) /34 K = 0 if non-keyed K= 9 + (keylen + ( 6* ((keylen+6/232)) + 6) /34 (if keyed) 1) I would imagine it can , but I am baffled as to where it would be specified. The most likely options are in the CDS, or IGDSMSxx. 2) See # 3. 3) SLED devices generated the recommendation for 1/2 track blocking for the following reasons: a) Maximizing the use of space. b) Minimizing physical IO to the device . With the advent of RAID devices, the physical IO portion has much less importance. There might be some performance IOS related overhead due to increase number of IO requests With the reduction in DASD prices, does the percentage of utilization matter as much as it used to I have not heard of any research in this area? Is Pat Artis still active, or has he retired? HTH, <snip> I have gone through a few manuals and cannot determine the answer to the following questions. Any guidance is appreciated 1) Can the SDB be adjusted from half-track to another setting (quarter or full)? 2) Are there any new best practices for SDB that have changed in the last 20 years? 3) Is Half-track still considered OPTIMUM? Since the storage arrays are so fast, I would think that maybe full track would not be that much of a performance impact any more. I have been working offlist with a couple of people with JCL and BLKSIZE and SPACE Sizing. I am trying to figure out how to make the formula more accurate. When I calculate space - I use full trace blocking. However, I find when SDB uses half-track, my math is off. </snip> ::DISCLAIMER:: ---------------------------------------------------------------------------- ------------------------------------------------------------------------ The contents of this e-mail and any attachment(s) are confidential and intended for the named recipient(s) only. E-mail transmission is not guaranteed to be secure or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or may contain viruses in transmission. The e mail and its contents (with or without referred errors) shall therefore not attach any liability on the originator or HCL or its affiliates. Views or opinions, if any, presented in this email are solely those of the author and may not necessarily reflect the views or opinions of HCL or its affiliates. Any form of reproduction, dissemination, copying, disclosure, modification, distribution and / or publication of this message without the prior written consent of authorized representative of HCL is strictly prohibited. If you have received this email in error please delete it and notify the sender immediately. Before opening any email and/or attachments, please check them for viruses and other defects. ---------------------------------------------------------------------------- ------------------------------------------------------------------------ ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
