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From: jjm@alice.UucP (John J. McCarthy)
Newsgroups: net.micro.att
Subject: Hard disk write speed on 6300
Message-ID: <5109@alice.uUCp>
Date: Mon, 10-Mar-86 18:43:21 EST
Article-I.D.: alice.5109
Posted: Mon Mar 10 18:43:21 1986
Date-Received: Wed, 12-Mar-86 04:17:13 EST
Organization: Bell Labs, Murray Hill
Lines: 24

I have an application in which the time required for writes
to the hard disk on my 6300 is critical.  (The application is
sampling speech at 10-20Khz.)  The program involves successive
writes of blocks of 4-8K.  I have found that the first write takes
more than twice as long as subsequent ones, which is too long.
I have also found that the time the first write requires is inversely
related to the number of disk I/O buffers specified in the config.sys
file.  That is, the write time contrarily is longer when there
are more buffers (say > 40 buffers of 512 bytes each).

I've also tried doing writes to the file of dummy data
and then seeking back to the beginning. This doesn't seem to help.

Does anyone have any experience with problems of this sort?
Evidently the seek is only logical, not physical. Is there
a work-around?  I'm using Lattice C v3.00.  Is there an optimal
number of I/O buffers for these requirements?

The disk is 10 megabytes, about half full.  It was recently reformatted,
so there is probably not too much fragmentation.

-- 
John McCarthy, AT&T Bell Labs, Murray Hill; 201 582-6595; alice!jjm
also Univ. of Mass., Amherst; 413 545-0889; mccarthy@umass-cs.csnet