In the mid-1970’s (or it may have been the early 1980’s, the memory is fainter now) I took an operating systems overview class at a technical college nearby, and the instructor was an IBM Fellow whose name I have long since forgotten, but in one class he told us a story about how VSAM came to be as we know it today. The following is my (perhaps faulty) memory of the story he told us.
The original Virtual Storage Access Method design was created by a group of people within IBM as a complete replacement for ALL then-existing access methods. When it was presented to the IBM powers, one of the marketing/sales honchos screamed loudly that the conversion costs for existing customers would clobber sales (and therefore profits) and that this could not be tolerated as the way forward. When the group that invented the idea refused to reduce the scope of the project, he took home the design paper and took out all the parts that would require IBM customers to convert existing code and processes, and the resulting design document became known as VSAM0 (VSAM zero) and this is the VSAM design that was implemented. I have never seen any actual history that describes the events around the creation of VSAM as he related them, but that instructor seemed quite believable at the time, and he was an IBM Fellow so you would think he knew whereof he spoke. Peter From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On Behalf Of Paul Gilmartin Sent: Friday, May 24, 2024 11:03 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: VTOCs vs. catalogs On Thu, 23 May 2024 22:24:06 -0500, Mike Schwab wrote: > >VSAM came from the Future Systems development as a complete >replacement, Lynn Wheeler has posts about that. >It was cut back to be an addition to MVS, then combined with CVOL >catalogs to ICF. > "complete replacement" of what, specifically? I have heard the assertion that VSAM was intended to replace all other access methods: QSAM, BSAM, BPAM, ... <Snipped> -- This message and any attachments are intended only for the use of the addressee and may contain information that is privileged and confidential. If the reader of the message is not the intended recipient or an authorized representative of the intended recipient, you are hereby notified that any dissemination of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by e-mail and delete the message and any attachments from your system. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
