theoretical question about disks and os

[Bill Hacker]

Raphael Marmier wrote:

Is it possible for a poorly written disk driver/filesystem to trash 
blocks on a hard disk? By trashing I mean that subsequent access result 
in an i/o error, aven accross reboot.
Of course.  But what is far more likely is a failure
elsewhere that happened to impact a disk write,
and/or a drive electronics intermittency.
That could have been triggered by a hardware failure,
software failure, high temperature, or power glitch
 - even a mere noise spike.
I have such a disk where it happened a few years ago. Curiously, the 
damaged blocks where the first blocks of partitions that where mounted. 
The maker's test software says the drive's ok, as well as s.m.a.r.t., 
although it needed a "reformat" with the same tool to get rid of the bad 
blocks.
Get your hands on a decent thermometer - digital indoor/outdoor with
one remote thermistor are cheap and cheerful - run the drive externally
and cover it to make it warm up.  Keep an eye on the temp so it doesn't
go over the maker's max 'operating' temp, loop an I/O test on it, and see
if it is OK when hot.
I would think it must be some kind of hardware failure, but a recent 
discussion about linux filesystems makes me wonder... linux was running 
on that disk, after all, with reaiserfs. And it was 3 years ago.

Raphael
ReiserFS of '3 years ago' was not known for perfection, but I
would look elsewhere first.
HTH,

Bill