My 'why' did any disk packs get damaged was never answered, or I've forgotten. I do know when I visited a few days later in the IBM FE's office was at lease one disk pack and either a couple heads and other parts.
On Sun, Dec 13, 2015 at 12:04 PM, Anne & Lynn Wheeler <[email protected]> wrote: > [email protected] (Pete Lancashire) writes: > > Showing my age .... > > > > I worked for Burroughs as an engineering technician. > > > > A customer with 360/65 instantaneous loss of power. I was there only > for a > > couple hours to drop off some equipment. Later heard they lost a couple > > disk packs. > > separate from power failures can precipitate disk drive failure. > > IBM CKD dasd had power loss failure mode ... where there wasn't enough > power to maintain memory contents ... but there was enough power left > for the controller to complete a write operation ... problem was that > the channel had stopped transferring data ... so the controller > continued writting all zeros. The result was that after recovery, a > subsequent read would show no errors ... for the record that had write > operation ("correctly") complete with all zeros (this was especially > troublesome when things like VTOC record was being written) > > FBA introduced that a physical record would not be written unless all > data was available to correctly complete a write. This philosophy > continued for RAID (write "failure" either completes correctly or > at least results in error indication for subsequent read). > > During the 80s, there was lots of work trying to figure out how to > retrofit such a fix to CKD dasd ... or at least provide a way for system > to recognize an incorrect trailing zeros write. > > -- > virtualization experience starting Jan1968, online at home since Mar1970 > > ---------------------------------------------------------------------- > 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
