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Date: Tue, 29 Oct 2002 02:31:33 -0800
From: David Schultz <dschultz@uclink.Berkeley.EDU>
To: Peter Wemm <peter@wemm.org>
Cc: "Daniel O'Connor" <doconnor@gsoft.com.au>,
	Chuck Robey <chuckr@chuckr.org>,
	Kenneth Culver <culverk@yumyumyum.org>,
	"Wilkinson, Alex" <Alex.Wilkinson@dsto.defence.gov.au>,
	hackers@FreeBSD.ORG
Subject: Re: [hardware] Tagged Command Queuing or Larger Cache ?
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	Daniel O'Connor <doconnor@gsoft.com.au>,
	Chuck Robey <chuckr@chuckr.org>,
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	"Wilkinson, Alex" <Alex.Wilkinson@dsto.defence.gov.au>,
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References: <1035861964.77698.83.camel@chowder.localdomain> <20021029042415.967662A88D@canning.wemm.org>
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Thus spake Peter Wemm <peter@wemm.org>:
> Actually, not even then.  Modern IDE drives only write entire tracks at a 
> time.  If you modify a single sector, then the drive has to read the entire
> track into the buffer, in-place edit the sector, and then rewrite the entire
> track.
[...]
> And that completely blows FFS's assumptions out of the water.  And what
> is sad is that many SCSI disks are similar these days.  But not all of
> them (I'm told).

I've heard this before.  It would be very useful to have
information about which drives have this misfeature, but I guess
it isn't the sort of thing that hard drive manufacturers like to
advertise.  Does anyone have any data on track-writing drives?

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