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Date: Wed, 14 Nov 2012 17:38:14 -0600 (CST)
From: Robert Bonomi <bonomi@mail.r-bonomi.com>
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To: freebsd-questions@freebsd.org
Subject: 'device' representation in the filesystem questions
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it appears that FreeBSD, at least 8.0 and later:
   a) no longer uses 'raw' devices for anything
   b) no longer uses 'block' devices for anything
   c) randomly assigns device 'major' numbers
   d) doesn't use device 'minor' numbers for anything.
   e) as a result of c) and d), there is no way to
      establish 'device' physical characteristics
      from the 'node' information.

Is there a wizzard who can confirm/deny?

Or, if there's a better place to ask, can anyone point me there?

There are significant performance and 'addressability' issues when doing
i/o directly to 'fixed block' devices, especially 'write-once' media.`

The classical 'block' device type was a reliable indicator of 'fixed block'
behavior,  how does one make that determination today?

Is there any way to get 'classic' mag-tape behavior -- where, for example
a read(2) returned the lesser of the bytes in the block, and positioned
to the beginning of the next, regardless of whether the etire content of
the current block had been read ?`