Date: Wed, 13 Apr 2005 14:11:39 +0200 From: =?ISO-8859-1?Q?S=F8ren_Schmidt?= <sos@DeepCore.dk> To: =?ISO-8859-1?Q?=22Arne_=5C=22W=F6rner=5C=22=22?= <arne_woerner@yahoo.com> Cc: FreeBSD Multimedia <freebsd-multimedia@freebsd.org> Subject: Re: Followup to DVD Burning question Message-ID: <425D0C7B.5070707@DeepCore.dk> In-Reply-To: <20050413115404.34207.qmail@web41203.mail.yahoo.com> References: <20050413115404.34207.qmail@web41203.mail.yahoo.com>
next in thread | previous in thread | raw e-mail | index | archive | help
Arne W=F6rner wrote: > --- S=F8ren Schmidt <sos@DeepCore.dk> wrote: >=20 >>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. >> >=20 > Why? I can read and write the same block of a DVD-RW round robin. > I mean: >=20 >>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 >=20 > ... > This looks just like a hard disc to me... 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 = it to work seamlessly. I guess this could be worked around in the burner = firmware but that would probably offend the DVD consortium ;) --=20 -S=F8ren
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?425D0C7B.5070707>