Re: theoretical question about disks and os

[Bill Hacker <wbh@xxxxxxxxxxxxx>]

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