From owner-freebsd-multimedia@FreeBSD.ORG Wed Apr 13 23:09:21 2005 Return-Path: Delivered-To: freebsd-multimedia@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 5258916A4CE for ; Wed, 13 Apr 2005 23:09:21 +0000 (GMT) Received: from odin.ac.hmc.edu (Odin.AC.HMC.Edu [134.173.32.75]) by mx1.FreeBSD.org (Postfix) with ESMTP id 0C1E543D1F for ; Wed, 13 Apr 2005 23:09:21 +0000 (GMT) (envelope-from brdavis@odin.ac.hmc.edu) Received: from odin.ac.hmc.edu (localhost.localdomain [127.0.0.1]) by odin.ac.hmc.edu (8.13.0/8.13.0) with ESMTP id j3DN9GvQ000498; Wed, 13 Apr 2005 16:09:16 -0700 Received: (from brdavis@localhost) by odin.ac.hmc.edu (8.13.0/8.13.0/Submit) id j3DN9FsZ000497; Wed, 13 Apr 2005 16:09:15 -0700 Date: Wed, 13 Apr 2005 16:09:15 -0700 From: Brooks Davis To: =?iso-8859-1?Q?S=F8ren?= Schmidt Message-ID: <20050413230915.GA20498@odin.ac.hmc.edu> References: <20050413115404.34207.qmail@web41203.mail.yahoo.com> <425D0C7B.5070707@DeepCore.dk> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="UugvWAfsgieZRqgk" Content-Disposition: inline In-Reply-To: <425D0C7B.5070707@DeepCore.dk> User-Agent: Mutt/1.4.1i X-Virus-Scanned: by amavisd-new X-Spam-Status: No, hits=0.0 required=8.0 tests=none autolearn=no version=2.63 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on odin.ac.hmc.edu cc: FreeBSD Multimedia Subject: Re: Followup to DVD Burning question X-BeenThere: freebsd-multimedia@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Multimedia discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 13 Apr 2005 23:09:21 -0000 --UugvWAfsgieZRqgk Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Apr 13, 2005 at 02:11:39PM +0200, S=F8ren Schmidt wrote: > Arne W=F6rner wrote: > >--- S=F8ren Schmidt wrote: > > > >>Arne W=F6rner wrote: > >> > >>>That's how I do backups with a DVD-RW: > >>> tar cf - ... | dd of=3D/dev/acd0 obs=3D32k conv=3Dosync > >>> > >>>Unluckily my DVD-RW's cannot be used for UFS with my > >>>burner... I do not know why. > >> > >>DVD-RW doesn't quite cut it for UFS, you need DVD+RW media for > >>that. > >> > > > >Why? I can read and write the same block of a DVD-RW round robin. > >I mean: > > > >>dd if=3Da of=3D/dev/acd0 bs=3D32k count=3D1 oseek=3D10 > >>dd if=3D/dev/acd0 of=3D /dev/null bs=3D32k count=3D1 iseek=3D10 > >>dd if=3Db of=3D/dev/acd0 bs=3D32k count=3D1 oseek=3D10 > >>dd if=3D/dev/acd0 of=3D /dev/null bs=3D32k count=3D1 iseek=3D10 > >>dd if=3Dc of=3D/dev/acd0 bs=3D32k count=3D1 oseek=3D10 > >>dd if=3D/dev/acd0 of=3D /dev/null bs=3D32k count=3D1 iseek=3D10 > > > >... > >This looks just like a hard disc to me... >=20 > I forgot the exact details, but the DVD-RW media (or rather the DVD-RW=20 > method of accessing RW media) doesn't allow for non 32K transfers,=20 > whereas the DVD+RW method does read-modify-write behind the scene to get= =20 > it to work seamlessly. I guess this could be worked around in the burner= =20 > firmware but that would probably offend the DVD consortium ;) One could write a GEOM that did read-modify-write to do blocksize translation. :-) -- Brooks --=20 Any statement of the form "X is the one, true Y" is FALSE. PGP fingerprint 655D 519C 26A7 82E7 2529 9BF0 5D8E 8BE9 F238 1AD4 --UugvWAfsgieZRqgk Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.1 (GNU/Linux) iD8DBQFCXaaaXY6L6fI4GtQRAjVKAKCWvndHo8faaYLKBOY+WVzo0gt72wCfQBQP +glMAq7Sv8mBZ7DsAUPfThc= =YiNs -----END PGP SIGNATURE----- --UugvWAfsgieZRqgk--