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Date:      Mon, 6 Nov 2000 20:50:03 -0800 (PST)
From:      Bruce Evans <bde@zeta.org.au>
To:        freebsd-bugs@FreeBSD.org
Subject:   Re: misc/21675: Better and more disktab entries for MO drives
Message-ID:  <200011070450.UAA24637@freefall.freebsd.org>

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The following reply was made to PR misc/21675; it has been noted by GNATS.

From: Bruce Evans <bde@zeta.org.au>
To: "W.H.Scholten" <whs@xs4all.nl>
Cc: freebsd-gnats-submit@FreeBSD.ORG
Subject: Re: misc/21675: Better and more disktab entries for MO drives
Date: Tue, 7 Nov 2000 15:49:28 +1100 (EST)

 On Sun, 5 Nov 2000, W.H.Scholten wrote:
 
 >  Correction for the disktab diff (se was 2048 for a 512 byte medium in
 >  the 230_max entry) and use of -m 0 in the newfs example. Plain diff (to
 >  the original disktab entry of e.g. fbsd 3.3R or 4.1R) attached.
 
 See a recent thread about fixing disklabel(8) (actually about making
 disklabel(8) easier to use).  There is no need for disktab entries
 for drives that report their size to the driver, except possibly for
 cloning a large number of identical drives with the same customized
 label (the min* entries for floppies are a good example of this), but
 customized labels belong in customized disktab files, not in the
 standard one (the min* entries belong since they are used by the system
 for building releases).
 
 >  +# ---- 90 mm magneto optical disk formats (dedicated disk): ----
 >  +# Prepare a disk as follows (e.g. using device da0):
 >  +#	disklabel -B -w -r da0 mo230
 >  +# or:
 >  +#	disklabel -w -r da0 mo640
 >  +# (the -B flag currrently doesn't work for 640 MB media).
 
 The problem seems to be in disklabel(8).
 
 >  +# and then:
 >  +#	newfs -t 0 -u 0 -m 0 da0a
 >  +# (t=0 and u=0 means the values from disklabel will be used for # tracks and
 >  +# # sectors).
 
 Are t and u worth forcing to the physical values for mo disks?  Are the
 physical values actually physical?  I force t and u for floppies, but the
 effects are mostly cosmetic (newfs doesn't really understand the weird
 geometry of 1 track with 4096 sectors, especially on a disk with only
 2880 sectors, and it prints confusing warnings which release engineers
 have been ignoring for too long).
 
 Bruce
 
 


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