In 1972, the Corporation's Annual P&L job read multiple tape reels from each of the 26 regional offices, so 26 tape drives were allocated to the job, which took over 40 hours across a dedicated weekend, and the operators were kept busy mounting and dismounting, but when they had all 26 drives mounted and spinning, and could take a breath to watch, it was a sight to behold.
It was so beautiful that one of the junior tape operators took a picture of the spinning tapes. With flash. Causing half of those spinning tape drives to abruptly open, because the optical sensor saw that flash of light as the reflector at the end of the tape, and ABENDing the job. Barry Merrill Herbert W. "Barry" Merrill, PhD President-Programmer MXG Software Merrill Consultants 10717 Cromwell Drive Dallas, TX 75229 [email protected] http://www.mxg.com - FAQ has Most Answers [email protected] - invoices/PO/Payment [email protected] - technical tel: 214 351 1966 - expect slow reply, use email fax: 214 350 3694 - prefer email, still works -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Robert A. Rosenberg Sent: Saturday, March 08, 2014 2:51 PM To: [email protected] Subject: Re: [OT ] Mainframe memories My memory was about an incident that occurred at an installation that I worked at. Their DASD were 2314s (which were 9 drive units - 8 live and one spare). The address of the drives were controlled by a round plug that could be removed and placed in the address hole of another drive. There were 2 of these units in the room addresses as 170 to 177 and 178 to 17F. The operator know that a job was going to start which was going to need a certain disk volume so to save time he placed it in the space drive of the 170-177 unit. When the job started, the system unmounted 17A and asked for the volume to be mounted there. To save time instead of spinning down the space where he had mounted the volume and placing it in the drive currently known as 17A (or the 178-17F Spare), he just moved the 17A plug into the spare's address hole. Since there was no difference between a xx2 and xxA plug (both are just indicate that they are the 3rd of 8 addresses on the control unit - the 2314 control unit was just wired to respond as 170-177 or 178-17F) suddenly there were 2 drives marked as 172. You can imagine the crash that then occurred killing a long running job using the real 172. The job had to be restarted from the beginning after the volume was restored. The operator was new there and was used to 3330s which only had 8 drives and no spares so this type of premount error could not occur since the new volume would have either been placed in a drive whose volume had been unloaded (and the system would have spotted it there and selected it) or it would have done the unload to free up the drive. ---------------------------------------------------------------------- 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
