🚀 go-pugleaf

In article <norman_walker-1604971308310001@moon.why.net>, norman_walker@why.net (Norman Walker) wrote:
>In article <5itdvn$2d1$1@hecate.umd.edu>, guthrie@cs.umd.edu (John G
>Guthrie) wrote:
> 
>> In article <stas-1204972004010001@a0103.chantilly.mns.net>, "Stas Pietrucha"
>> <stas@mnsinc.com> wrote:
>> >* $100 Apple Stylewriter II printer
>> >* $10 Video adapter to use VGA and SuperVGA monitors with your Mac
>> >* $50 Apple Scanner
>> >* $5 Windows-compatible Joystick
>> >* $20 Apple TV/Video Card remote control
>> >More details and more stuff for sale at:
>> > http://www.mnsinc.com/stas/forsale.html
>> 
>> This person knowingly sold me a hard drive with bad sectors even though I 
>> specified my offer was contingent on the drive having NO BAD SECTORS.  He
>> now 
>> refuses to give me a full refund, saying that "I took my chances buying on
>> the 
>> internet".  He has only offered a partial refund, saying "take it or leave 
>> it".  
>
>
>John,
>I don't know what you were or weren't promised, but just for the record,
>there's no such thing as a hard drive with NO bad sectors.  You might not
>be able to see them with Apple's formatting software, but if you look at
>them with something like Hard Disk Toolkit or a comparable software
>package, you WILL find bad sectors. They have just been mapped out!
>
>I shouldn't say that there is ABSOLUTELY no such thing as a hard drive
>with no bad sectors, but the LIKELIHOOD of that happening (especially with
>the large capacities of modern drives) is ALMOST nonexistant.
>Regards,
>Norman
>

Let me provide a little more detail.  Yes, hard drives come with some "spare" 
sectors which can be used to substitute for bad ones.  There are low level 
scan and repair utilities which will find the bad sectors and reassign spare 
sectors to them.  At the logical level (after this repair operation) the drive
appears to have no bad sectors; that is, one can FORMAT the disk and/or 
SCANDISK it (or whatever the Apple equivalent is) and the user will be told 
that there are 0 bad sectors.  I think this is what most people have in mind 
when they specify that a drive have no bad sectors -- that it has no bad 
sectors at a LOGICAL level.  In actual fact the drive may have a FEW bad 
sectors, but not more than can be replaced from the limited supply of spare 
sectors.

Now, in this particular case I received a drive which had only one partition 
defined on it covering only 75% of the available cylinders; 25% of the disk 
was not even available in this configuration.  This one, partial partition 
did, in fact, check out as having no bad sectors with SCANDISK.  Of course, 
like anyone, when I pay for a disk drive I am generally assuming that I will 
be able to use 100% of the available space on it.  I used a Western Digital 
utility called WDAT_IDE (the drive is a WD Caviar series) to do a low level 
surface scan and write/verify test over the entire drive.  What I discovered 
was that the drive was fine until about cylinder 760 of 1024.  At that point I
started getting numerous bad sectors and other hardware errors.  The number of
bad sectors was many orders of magnitude more than could be massaged out by 
re-assigning spare sectors.  So, basically the last 25% of the cylinders on 
the drive are completely unusable.  Now it suddenly made sense why there was 
only one partition defined which used only 75% of the available space -- that 
was someone's deliberate attempt to salvage the remaining usable space from 
this obviously damaged disk drive.  I have nothing against people trying to 
salvage their own defective drives; I do take issue, however, with being sold 
one under the false presumption that the drive has no problems and can utilize
100% of it specified storage space.

--John Guthrie