Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!lll-winken!uunet!mcsun!corton!chorus!opera.chorus.fr!mir
From: mir@opera.chorus.fr (Adam Mirowski)
Newsgroups: comp.sys.ibm.pc.misc
Subject: Re: disk transfer rates
Message-ID: <11094@chorus.fr>
Date: 19 Jun 91 13:46:48 GMT
References: <1991Jun11.1489.6865@canrem.uucp>
Sender: mir@chorus.fr
Reply-To: mir@opera.chorus.fr (Adam Mirowski)
Distribution: comp
Organization: Chorus systemes, Saint Quentin en Yvelines, France
Lines: 24

In article <1991Jun11.1489.6865@canrem.uucp>, jack.lupic@canrem.uucp (jack lupic) writes:

%% Recently I have upgraded to a 10Mhz/AT with an AT 16 Bit controller.
%% I am also using a 71 Mb/28Msec Imprimis and 42 Mb/28Msec Seagate drive.
%% What I was told is to use 2:1 interleave when formatting the disks.
%% 
%% Measuring the transfer rate with Norton Sysinfo, I get 170Kb/sec for 
%% the first drive and 240Kb/sec for the second drive.  Could anyone 
%% reasonably tell me what transfer rates I should be getting?

With the standard drives you have 17 sectors per track, or 8.5 Kb. The disk
rotates at 60 rotations per second, and only one track is read at once. So
the binary stream is 60 * 8.5 Kb/s = 510 Kb/s max for 1:1 interleave with no
caching.

That means that the drive with 170Kb/s has been low-level formatted with the
3:1 interleave (3 rotations to read all the sectors on a track) and the drive
with 240 Kb/s has been low-level formatted with the 2:1 interleave (2 rotations
to read an entire track). The difference of 255 - 240Kb is probably due to
the controller missing a sector from time to time.

-- 
Adam Mirowski,  mir@chorus.fr (FRANCE),  tel. +33 (1) 30-64-82-00 or 74
Chorus systemes, 6, av.Gustave Eiffel, 78182 Saint-Quentin-en-Yvelines CEDEX