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To: "Gary Palmer" <gpalmer@freebsd.org>
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Subject: Re: Is my disk going bad? 
In-reply-to: Your message of "Thu, 24 Oct 1996 21:07:23 EDT."
             <5217.846205643@orion.webspan.net> 
Date: Thu, 24 Oct 1996 22:40:34 -0400
From: Bakul Shah <bakul@plexuscom.com>
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> Quantum 4Gb's here seem to not remap on soft reads, or gather bad
> sectors extremely fast. Reallocation was on on the drives too...

The idea is grab the data on a marginal block before it goes bad
permanently.  You can try a number of different things on a soft
read error:
a) remap on the very first read error,
b) keep track of the number of soft read errors and remap after
   some magic number,
c) rewrite the data and see if the soft read error goes away, 
d) a combination of b) and c), or
e) do nothing.

Each option has its pros and cons.

But it has been years since I last looked at this stuff and Quantum
may be using something totally different.