On Thu, 15 Jul 2004, Rick Stevens wrote: > Benjamin J. Weiss wrote: > > I believe that this is what is called a "low level" format. IIRC, it > > formats all of the sectors, both good and bad and resets the flags. Then > > it reserves a bunch of sectors as spares. Then it tests all of the > > sectors to see if they'll hold the data properly. If the software detects > > a problem, it flags the bad sector and brings a spare into use, just as > > James said. > > I used to work for Micropolis and we made hard drives. All hard drives > have bad sectors on them. The maker reserves a bunch of good sectors to > be used as replacements and the first format tags the bad sectors and > modifies a remapping table on the drive which causes it to go to one of > the spares whenever one of the bad sectors is referenced. > > As time goes on and other sectors go bad, a "low level" format finds > the new bad sectors and further modifies the remapping table to use more > of the spare sectors. S.M.A.R.T. drives are supposed to be able to do > this on the fly. > > Eventually, the drive will run out of spare sectors and you can't > successfully low level format it any more. The manufacturer can wipe > the original remap table and go through it again, but by that time the > drive is usually well past its MTBF and it's somewhat silly to try to > push it any further. Thanks, Rick! I'm glad to get my misconception fixed. :) Like they say, you learn something new every day, and this was today's. ;) Ben
