theoretical question about disks and os

[Bill Hacker]

Raphael Marmier wrote:


The two models that failed me are
a 20Gb DPTA-372050 (DEC-1999)
That, and its 15 GB sibling were among the
more reliable ones, in our experience. That said,
the Deskstar line only had 1 yr wty.
a 40Gb IC35L040AVER07-0 (OCT-2001)
Several 60GB failures in that family, but most
ran 24 X 7 for longer than their warranty, and at least
one was fried by a capacitor failure (along with the
MB).
In our case, these were all part of an atacontrol RAID1
mirror set in whuch the other identical drive survived,
(as did the CPU on several of the otherwise trashed MB).
I know there is a 60Gb IBM drive in my Mac (august 2002), which I 
decided to trust because I thought Apple would have made sure these 
drive where not from defective runs.

How would they go about doing what the factory QC
had failed to do?
Bill