Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!uunet!mcsun!hp4nl!philapd!ssp2!pb
From: pb@idca.tds.PHILIPS.nl (Peter Brouwer)
Newsgroups: comp.unix.sysv386
Subject: Re: mkfs and disk performance
Message-ID: <630@ssp2.idca.tds.philips.nl>
Date: 31 Aug 90 05:46:27 GMT
Reply-To: pb@idca.tds.philips.nl (Peter Brouwer)
Organization: Philips Information Systems, Apeldoorn, The Netherlands
Lines: 39
Summary:
Expires:
References:<1990Aug21.050638.15737@cimcor.mn.org> <536@fciva.FRANKLIN.COM> <628@ssp2.idca.tds.philips.nl> <3295@segue.segue.com>
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Organisation: Philips Information Systems, Apeldoorn, The Netherlands
Disclamer: This is mine opinion alone.
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 In article <3295@segue.segue.com> jim@segue.segue.com (Jim Balter) writes:
>In article <628@ssp2.idca.tds.philips.nl> pb@idca.tds.philips.nl (Peter Brouwer) writes:
>>To be precise, the gap determines the way the free block space is organised.
>
>That is neither precise nor correct.  The gap is the rotational gap,
>which is the offset between the logical track start from one track to another.
>This offset is to account for track-to-track seek time; if it is just right,
>the next block will be under the read head just as it settles over the track. 
>It has nothing to do with free space, unless your system has taken this value
>over for something other than its original purpose.  The gap was important
>back when UNIX ran off of RK05's; modern disk controllers should optimize
>track formatting for contiguous I/O.

I think you are confused by the term gap.
It is also used in disk format layout definitions. 
In unix it has the meaning as I described it. Info was retrieved from the 
sources of mkfs and fsck.
















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