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Date:      Sun, 31 May 1998 16:54:17 -800
From:      walton@nordicdms.com (Dave Walton)
To:        Greg Lehey <grog@lemis.com>, freebsd-questions@FreeBSD.ORG
Subject:   Re: fdisk slice oddities
Message-ID:  <19980531235417422.AAA277@mail.nordicdms.com>
In-Reply-To: <19980530185741.K20360@freebie.lemis.com>
References:  <19980530073409264.AAA277@mail.nordicdms.com>; from Dave Walton on Sat, May 30, 1998 at 12:34:09AM %2B0000

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On 30 May 98 at 18:57, Greg Lehey wrote:

> Dedicated mode.  It's not only  not dangerous, it's safer than
> non-dedicated mode.

Really?  Why is it safer?  Sysinstall calls it "dangerously 
dedicated", BTW.


> > Is there some particular reason why dangerously dedicated mode
> > changes the drive geometry?
> 
> It might come closer to getting it right.

That's just it...  It's not changing to a more correct geometry, it's 
changing to a geometry with < 1024 cylinders.  For example, on this 
6.5GB drive that I'm working with right now, dmesg and fdisk report 
the geometry as 13328/15/63.  If I use the whole disk in "dedicated 
mode", the geometry changes to 784/255/63.


> I suppose the most important difference is that no modern disks have a
> rigid geometry any more (in other words, the terms cylinders, heads
> and sectors are all faked).  All we care about is the LBA (logical
> block addressing) mode.  

Which is why I'm surprised that fdisk changes to something other than 
LBA mode for "dedicated mode".


> Apart from the observation, did you have any problems?

No, it just strikes me as a peculiar behavior, so I thought I'd 
mention it.

By the way, given the choice between an LBA geometry and a <1024 
geometry, is there any particular reason to go with one over the 
other?

Thanks,
Dave


----------------------------------------------------------------------
Dave Walton                                                           
Webmaster, Postmaster                   Nordic Entertainment Worldwide
walton@nordicdms.com                          http://www.nordicdms.com
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