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Date: Wed, 27 Sep 1995 16:21:41 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199509270621.QAA08365@godzilla.zeta.org.au>
To: hackers@FreeBSD.org, nate@rocky.sri.MT.net
Subject: Re: Diskslice naming convention?
Cc: bde@FreeBSD.org
Sender: owner-hackers@FreeBSD.org
Precedence: bulk

>So, am I right in saying that other than the 'compatability' slice of
>/dev/xd#a for the root partition, the naming scheme is as follows:

>X = generic device name.
># = disk number
>Y = slice number (ie; one of the 4 'fdisk' partions')

>Xd#asY  (where 'a' could be any lower-case letter 'a-h')

No, Y may be any fdisk partition or logical drive, and 'a' follows the
slice number.

>BTW - Are slices named 1-4 or 0-3?

No, slices are named 1-30.

>Anyway, we create a FreeBSD slice by setting it's ID to 0xA5.  Then, we
>build a disklabel onto this 'slice' which gives us individual partitions
>on that slice.  Are there any 'special' partitions in this disklabel?

c.

>How would I read the *entire* FreeBSD portion of the slice?  How about

There is no such thing as a `portion' of a slice.  (Would a portion be
smaller or larger than a partition? :-).)  `dd if=/dev/rxd#sY' or `dd
if=/dev/rxd#sYc' reads the entire slice sY.  These devices are
identical.  /dev/MAKEDEV creates both for convenience.  The c partition
is special whether there is a disklabel describing it or not.  If there
is a disklabel, the c partition should match the whole slice.

>the entire disk?  How do I create a FreeBSD partition which accesses a
>DOS slice?

`dd if=/dev/rxd#' reads the entire disk.  /dev/rxd# is a completely
different device from /dev/rxd#c.  These devices are often confused
because disklabel automatically translates from `xd#' to /dev/rxd#c'.

You can't create a FreeBSD partition which accesses a DOS slice.  Just
access the DOS slice directly.

>Is there anything other documentation other than the the 'diskspace.FAQ'
>and the sources available?

Not much.  Perhaps there are 100 replices like this in mail archives.

Bruce