From owner-freebsd-hackers  Tue Sep 19  8:58:38 2000
Delivered-To: freebsd-hackers@freebsd.org
Received: from urban.iinet.net.au (urban.iinet.net.au [203.59.24.231])
	by hub.freebsd.org (Postfix) with ESMTP
	id 8A9AD37B43C; Tue, 19 Sep 2000 08:58:26 -0700 (PDT)
Received: from popserver-02.iinet.net.au (popserver-02.iinet.net.au [203.59.24.148])
	by urban.iinet.net.au (8.8.7/8.8.7) with ESMTP id XAA10960;
	Tue, 19 Sep 2000 23:58:21 +0800
Received: from jules.elischer.org (reggae-38-16.nv.iinet.net.au [203.59.172.16])
	by popserver-02.iinet.net.au (8.9.3/8.9.3) with SMTP id XAA01515;
	Tue, 19 Sep 2000 23:58:17 +0800
Message-ID: <39C78D0E.7DE14518@elischer.org>
Date: Tue, 19 Sep 2000 08:58:06 -0700
From: Julian Elischer <julian@elischer.org>
X-Mailer: Mozilla 3.04Gold (X11; I; FreeBSD 5.0-CURRENT i386)
MIME-Version: 1.0
To: Marc Tardif <intmktg@CAM.ORG>
Cc: freebsd-fs@freebsd.org, freebsd-hackers@freebsd.org
Subject: Re: device timings
References: <Pine.LNX.4.10.10009191138220.8544-100000@Gloria.CAM.ORG>
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Sender: owner-freebsd-hackers@FreeBSD.ORG
Precedence: bulk
X-Loop: FreeBSD.ORG

Modern disks pack different ammounts of data on different
tracks.. (the outside tracks are longer right?)

so at a constant speed (rpm) outside tracks have more data passing
below the head per given time than teh inside tracks do...

this seems pretty normal to me..




Marc Tardif wrote:
> 
> Considering the following disk configuration:
> ******* Working on device /dev/rwd0 *******
> parameters extracted from in-core disklabel are:
> cylinders=256 heads=132 sectors/track=63 (8316 blks/cyl)
> 
> parameters to be used for BIOS calculations are:
> cylinders=256 heads=132 sectors/track=63 (8316 blks/cyl)
> 
> Media sector size is 512
> Warning: BIOS sector numbering starts with sector 1
> Information from DOS bootblock is:
> The data for partition 1 is:
> sysid 165,(FreeBSD/NetBSD/386BSD)
>     start 63, size 1937565 (946 Meg), flag 80 (active)
>         beg: cyl 0/ sector 1/ head 1;
>         end: cyl 232/ sector 63/ head 131
> The data for partition 2 is:
> sysid 0,(unused)
>     start 1937628, size 58212 (28 Meg), flag 0
>         beg: cyl 233/ sector 1/ head 0;
>         end: cyl 239/ sector 63/ head 131
> ...
> 
> Now considering the following timings done with dd, how come I get such
> different transfer rates (bytes/sec) for s1 and s2? I understand there
> should be a difference between the block and character interface, as shown
> in the first two timings, but why isn't the same difference shown for the
> last two timings?
> 
> # dd if=/dev/wd0s1 of=/dev/null bs=8316b count=5
> 5+0 records in
> 5+0 records out
> 21288960 bytes transferred in 8.580486 secs (2481090 bytes/sec)
> 
> # dd if=/dev/rwd0s1 of=/dev/null bs=8316b count=5
> 5+0 records in
> 5+0 records out
> 21288960 bytes transferred in 4.058639 secs (5245344 bytes/sec)
> 
> # dd if=/dev/wd0s2 of=/dev/null bs=8316b count=5
> 5+0 records in
> 5+0 records out
> 21288960 bytes transferred in 6.066568 secs (3509226 bytes/sec)
> 
> # dd if=/dev/rwd0s2 of=/dev/null bs=8316b count=5
> 5+0 records in
> 5+0 records out
> 21288960 bytes transferred in 6.015735 secs (3538879 bytes/sec)
> 
> To Unsubscribe: send mail to majordomo@FreeBSD.org
> with "unsubscribe freebsd-fs" in the body of the message

-- 
      __--_|\  Julian Elischer
     /       \ julian@elischer.org
    (   OZ    ) World tour 2000
---> X_.---._/  presently in:  Perth
            v


To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-hackers" in the body of the message