Date: Wed, 14 Nov 2012 17:38:14 -0600 (CST) From: Robert Bonomi <bonomi@mail.r-bonomi.com> To: freebsd-questions@freebsd.org Subject: 'device' representation in the filesystem questions Message-ID: <201211142338.qAENcEqx002393@mail.r-bonomi.com>
next in thread | raw e-mail | index | archive | help
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 ?`
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201211142338.qAENcEqx002393>