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From: cmf851@anu.oz.au (Albert Langer)
Newsgroups: comp.unix.sysv386
Subject: Re: Mapping abs sector numbers to files
Message-ID: <1991Jun20.172754.13086@newshost.anu.edu.au>
Date: 20 Jun 91 17:27:54 GMT
References: <1991Jun14.181849.3725@newshost.anu.edu.au> <1058@dumbcat.sf.ca.us> <9106171448.32@rmkhome.UUCP>
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In article <9106171448.32@rmkhome.UUCP> rmk@rmkhome.UUCP 
(Rick Kelly) quotes and writes:

>>The last time I mapped out a bad sector by hand I lost a chunk of the
>>/usr/lib/news directory.  (I always wait until after doing a full backup
>>before mapping anything out).  Think of the problems that would occur of this
>>happened automatically.

>However, most SCSI drives can be modeselected to do auto bad sector mapping.
>But, as you say, this isn't the most desirable option.  The Bernoulli box
>does this by default.

Why do you agree that auto bad sector mapping is undesirable? The argument
quoted assumed that it would "automatically" lose chunks of needed files,
when in fact that was clearly a result of NOT implementing automatic SCSI
re-mapping and instead waiting until an unrecoverable hard error had
actually lost data.

My understanding is that the automatic remapping would occur when "too
many" soft errors were happening for a particular sector (as defined
by those with the best knowledge of drive failure characteristics - the
drive manufacturer). This would result in the data being preserved by
the remapping, so no missing chunks.

Waiting for a "hard" failure on the other hand would result in manual
re-mapping and lost data.

--
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