On Tue, 2017-09-26 at 14:19 -0400, Ethan via cctalk wrote: > I don't know if it's a good idea to low level format a drive or not.
Low-level formatting (which, at the time, was just called "formatting") used to be quite a routine operation on ST-506 MFM and RLL hard disks. They usually came completely blank from the factory and you had to format them according to whatever sector layout and interleave your particular controller wanted before they were usable. Once the drive was formatted you then had to run a separate process to lay out an actual filesystem. For MFM controllers on ISA cards I think the formatter was usually in the BIOS. For separate MFM controllers with a SCSI interface (Xebec S1410 kind of things) you used the FORMAT UNIT command. Newer ATA/SCSI drives with integrated electronics tended to come preformatted and there often wasn't any way to execute a low-level format even if you wanted to. At about the same time they started using embedded servo data on the disk itself for head positioning which made it impossible to do a low-level format in the field. I can't immediately think of any class of device on which attempting to execute a low-level format would be an actively bad idea (apart from destroying your data of course). On older ones it would work, on newer ones the drive would refuse the command, but in neither case is there likely to be any bad consequence. Was there a time in the middle when something bad would happen? p.
