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From: cckweiss@castor
Newsgroups: comp.sys.mac.hardware
Subject: Re: Hard Disk "interleave"
Summary: Interleave relates to machine speed
Message-ID: <7635@aggie.ucdavis.edu>
Date: 2 Jul 90 22:44:14 GMT
References: <13801@wpi.wpi.edu>
Sender: usenet@aggie.ucdavis.edu
Reply-To: cckweiss@castor.ucdavis.edu    Ken Weiss ()
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Organization: University of California, Davis
Lines: 35

In article <13801@wpi.wpi.edu> macman@wpi.wpi.edu (Chris Silverberg) writes:
>Hi!
>
>Can someone help explain to me the "interleave" characteristic of hard drives?
>I have a new Quantum HD, and when formatting, it asks me for the desired
>interleave. (1, 2, 3, or 4). Currently I have the HD installed internally
>on my MacSE. (no accelerations or anything).
>
>Specifically, what interleave SHOULD I be using, and what advantages/
>disadvantages/side effects are of using the right and wrong selection?
>
>Thanks much!
>
>- Chris 
> ._._._._._._._._._._._._._._._._._._.._._._._._._._._._._._._._._._._._._._.
>   Chris Silverberg                     AOL:   Silverberg
>   Worcester Polytechnic Institute      GEnie: C.Silverberg
>   INTERNET: macman@wpi.wpi.edu         SYSOP: Main Street U.S.A. BBS
>   FIDONET:  322/575.1                         508.832.7725  (1200/2400)

Interleave refers to the number of physical disc sectors skipped between
each logical sector. The interleave is created to allow slower 
processors to digest one sector worth of data before the next one
comes along. If interleave is too large things slow down a little,as
the processor is waiting for the next logical sector to come into
position under the r/w head. If interleave is too small then things
slow down a lot, as the next logical sector will be past the r/w head
before the processor is ready to accept the data. When this happens
the system must wait a full disk rotation for the correct physical
sector to come around again.

On an SE most manufacturers seem to recommend a 3:1 interleave, but
hey, what to they (or I) know...

Ken Weiss