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Date: Tue, 13 Mar 2001 01:36:13 -0600
To: Allen Landsidel <all@biosys.net>,
	Jean-Marc Zucconi <jmz@FreeBSD.ORG>
From: "Jeffrey J. Mountin" <jeff-ml@mountin.net>
Subject: Re: UDMA 33/UDMA 100 perfs
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At 01:39 AM 3/13/01 -0500, Allen Landsidel wrote:

>The point of a higher bus speed is not to get higher transfer rates from a 
>single drive, but to avoid saturating the bus when you have multiple 
>drives on a single channel of a controller.  This is true of both IDE and SCSI.

Here we go again.

Check the archives and consider a retraction of this.


>The above mentioned drive is a Western Digital "Protoge", their lowest-end 
>drive family.  It may be ATA-100, but it's also 5400RPM.  Their site tells 
>us this drive has minimum to-media transfer rate of 24MB/s, and a maximum 
>transfer rate of 40MB/s.  What rate you get will dependant upon where your 
>data is located on the disk.  The closer to the outside of the disk, the 
>faster your transfer rates will be.
>
>It looks to me like Mr. Zucconi is getting exactly the performace he 
>should expect out of that drive.  If you want better performance, you have 
>a few options.  All of them, unfortunately, involve buying more hardware.

Which is exactly why I said what I said and why I grew sick of manufactures 
hyping new transfer standards when no drives could hardly saturate the 
previous standard and end lusers think there was something to gain with 
their old drives on new controllers.


>1. Buy a drive with faster to and from media characteristics.  Higher 
>drive rpm, and higher data density will contribute to this to a degree.
>
>2. Set up a RAID, either through outlay of some $$ for a hardware 
>controller, or by using vinum.

You forgot or don't know about:

3)  Consider using only one drive per controller for maximum performance.


Jeff Mountin - jeff@mountin.net
Systems/Network Administrator
FreeBSD - the power to serve


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