Messages in this thread | | | Date | Tue, 14 Oct 2003 13:57:42 +0400 | From | Hans Reiser <> | Subject | Re: Why are bad disk sectors numbered strangely, and what happens to them? |
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Rogier Wolff wrote:
>On Tue, Oct 14, 2003 at 12:45:34PM +0400, Hans Reiser wrote: > > >>Perhaps we should tell people to first write to the bad block, and only >>if the block remains bad after triggering the remapping by writing to it >>should you make any effort to get the filesystem to remap it for you. >>What do you think? >> >>Rogier has not indicated that he has tried writing to the bad sector, >>has he? >> >> > >Hans, > >I simply refuse to try to trigger a remapping by writing to the >sector. A couple of things can happen: > >1) The write succeeds on the "bad" spot. > > The "normal" write doesn't >do a "veriy-after-write", so the write might simply be succeeding, >resulting in an immediate data-loss (which might be masked if I try >to reread the data from userspace bacause the data is still cached!) > Do a hard reboot with > 25 seconds power off.
> >2) the realloc might succeed, hiding the fact that my drive just lost >0.5k bytes of my data. I mean, there was SOME data there. Linux >wouldn't try to be reading it if it had never been written, right? A >drive that refers my data to /dev/null should be diverted there >itself. > >Of course, I left my drive that indicated it had problems (i.e. it >didn't spot the sector going bad before it became unreadable), in the >machine for another two days. It's getting replaced ASAP (i.e. the >next hour or so). > >The bad sector developed in a backup of data that is still running >hapilly on another machine. But I'm not risking a sector getting >assigned some important data going bad next time I notice something. > > Roger. > > > replacing the drive is reasonable caution. I think though that the other poster is right that IFF you want to remap bad blocks, the drive should do it not reiserfs.
-- Hans
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