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Date:      Tue, 1 Oct 2002 20:15:47 -0300 (ART)
From:      Fernando Gleiser <fgleiser@cactus.fi.uba.ar>
To:        "Weston M. Price" <wmprice@direcway.com>
Cc:        freebsd-questions@freebsd.org
Subject:   Re: Character Devices vs. Block Devices
Message-ID:  <20021001201058.D81915-100000@cactus.fi.uba.ar>
In-Reply-To: <200210011612.08538.wmprice@direcway.com>

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On Tue, 1 Oct 2002, Weston M. Price wrote:

> So, given this, I am assuming that hard drives are treated as raw devices
> exclusively? That is, no intermediate buffers are maintained between the user
> process and the device:

Nope, there is buffering for the file system interface.
I dont remember the exact reasons for nuking the block devices, but I
think it has to do with the new VM subsystem and the integrated
buffer cache/VM, but my memory may be failing.

If you want a more acurate answer, search the archives for -hackers and
-current

>
> Is this valid on FreeBSD?

Nope. The book was written before FreeBSD nuked block devices.


			Fer

>
> Regard,
>
> Weston
>
> On Tuesday 01 October 2002 03:19 pm, Weston M. Price wrote:
> > Hello,
> > 	A quick ls of my dev directory revealed that each one of my hard drives is
> > considered a character device by the system. Example:
> >
> > crw-r-----  2 root  operator  116, 0x00010002 Aug 19 16:09 /dev/ad0
> > crw-r-----  2 root  operator  116,   0 Aug 19 16:09 /dev/ad0a
> > crw-r-----  2 root  operator  116,   1 Aug 19 16:09 /dev/ad0b
> > crw-r-----  2 root  operator  116,   2 Aug 19 16:09 /dev/ad0c
> > crw-r-----  2 root  operator  116,   3 Aug 19 16:09 /dev/ad0d
> > crw-r-----  2 root  operator  116,   4 Aug 19 16:09 /dev/ad0e
> > crw-r-----  2 root  operator  116,   5 Aug 19 16:09 /dev/ad0f
> > crw-r-----  2 root  operator  116,   6 Aug 19 16:09 /dev/ad0g
> > crw-r-----  2 root  operator  116,   7 Aug 19 16:09 /dev/ad0h
> >
> > What I am confused about, aren't hard drives treated as block devices on
> > most systems? What am I missing?
> >
> > Regards,
> >
> > Weston
> >
> >
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>
>
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