Defect Lists

[John DiMarco]

In list.sun-spots you write:

>Periodically someone will ask for the manufacturer's defect list on some
>old disk drive.  What use is that, considering that formatting the disk
>generates a new defect list?  Seems sort of like asking for the shop
>manual on your Deuce street rod.

Some defects don't show up at format time. They wait until the most
inopportune moment...  Disk defects don't usually go away. The set of
actual defects on an old disk is a superset of the original set of
defects, recorded in the manufacturer's defect list. 

Every entry in the manufacturer's defect list indicates a definite bad
spot on the disk. You don't want to trust format/verify to find them all;
a few may be "weak" spots (inconsistently bad). 

John DiMarco                   jdd at db.toronto.edu or jdd at db.utoronto.ca
University of Toronto, CSRI    BITNET: jdd%db.toronto.edu at relay.cs.net
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