Oleg Drokin wrote: >Hello! > > Basically uyou'd better search for this on HDD vendors sites. > What's going on is simply can be described this way: > You write some block to HDD, if HDD decides the block is bad for some reason > and remapping is allowed (usually by tiurning on SMART), block is written to > different on-platter location and drive adds one more entry to its > remaped-blocks list. Next time you read this block, drive consults its > remapped blocks list and if block is remapped, reads it from new location > with correct content. > Described mechanism works for writing. > Actually I've seen something that looks like remapping on read, though > I have no meaningful explanation for that (except that they may have some > extra redundant info stored when you write data to disk, so that if sector > cannot be read, its content is restored with that redundant information and > sector is then remapped.). And this process takes a lot of time. > >Bye, > Oleg >On Mon, Aug 19, 2002 at 03:58:30PM +0100, Newsmail wrote: > > >>Hello Hans and Oleg, >>maybe its an offtopic question, but Hans always talks about leaving the >>hard disk to remap the bad blocks by itself. could you explain it in some >>words, how all this works, what happens after, and since when it exists, or >>do you have any special URL explaining this? >>thx in advance, >>greg >> >> >> >> >> > > > > Just taking a guess, many hard drives have difficult and time-consuming procedures that they can go through to read a troublesome block. These can take 20-30 seconds. Probably if they have to go through these procedures, once they finally succeed the smart vendors remap the block.
Hans
