Greg Freemyer said the following on 04/25/2013 08:52 AM:
You don't seem to understand the bad sector life cycle. Here you go:
- Sector magnetism becomes degraded. - Time passes (hours, days, years) - A sector read of that specific sector occurs. - A sector error is returned to the userspace app and smart marks the sector bad - all subsequent reads continue to attempt to read from the same bad sector. That is they typically fail as well. - time passes (seconds, days, years) - a write to the bad sector occurs - drive controller notes this sector is bad, time to remap it - sector remapped and new data written - reads now succeed
Damn Right! More years ago than I care to remember I wrote a package that did that for the old CDC 9766 300 MB style drives. Time passed (years) and now its all in the drive electronics :-) The only difference I can think of was that also wrote a utility to manipulate the 'look-aside' mapping so that I could map out a bad sector on the basis of it being logged as bad on reading. It was really up to the admin to try and do a best-effort of reconstituting the data. Still, back in those primitive days, the V7 UNIX file system had a mechanism whereby a hidden file (inode #0 was it?) could have bad blocks linked to it so that they were never allocated to a file. I don't think there was a tool to do this and I can't recall if the MKFS of those days did it for you - I think it didn't. We've come a long way since then. Those 300MB drives took two people to lift and load into a 19" rack. Now I have a 32GB "drive" that's the size of my thumb nail. -- Wherever you see a successful business, someone once made a courageous decision. --Peter F. Drucker -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org