Date: Mon, 7 Jan 2008 19:49:46 +0000 From: Kimi <kimimeister@gmail.com> To: "Martin Laabs" <martin.laabs@mailbox.tu-dresden.de> Cc: freebsd-questions@freebsd.org Subject: Re: minimum valid block size on DVD-RAM Message-ID: <42b497160801071149u1cac6122pce67ef31f399a53@mail.gmail.com> In-Reply-To: <op.t4ki0bfc724k7f@martin> References: <op.t4ki0bfc724k7f@martin>
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On 07/01/2008, Martin Laabs <martin.laabs@mailbox.tu-dresden.de> wrote: > Hi, > > I'm investigating a problem concerning the minimum valid block > size accepted by DVD (writing) devices when writing > on a DVD-RAM. (Please don't mix DVD-R, DVD-RW and DVD-RAM up > here.) > > My motivation for this is the handbook chapter 18.7.9 that > describes how to format a DVD-RAM. All listed commands works > on a blocksize of 512 byte. This does not work for me on an > 'Optiarc DVD RW AD-7170A/1.02' device since it refuse every > operation with a blocksize unequal to a multiple of > 2048 bytes. > > The actual inherent (physical) block-/sector size on > a DVD-RAM is, like on nearly all other DVDs and CDs, > realy 2048 byte so the behaviour of my device makes sense > to me. (How should it write a quarter sector?) > > Now Marc Fonvieille let me know that the instructions in > the handbook has been submitted by a DVD-RAM user. This > means that these instruction works at least at one system. > I'd now like to know whether most of the available DVD-writers > are capable of writing blocks smaller than 2k. If not it > would be worth investigating an alternativ instruction set. > (But this is not as simple as it seems because newfs seems > to have a bug with the -S option and also bsdlabel works > as default on 512 byte blocks) > > Since I don't have access to different DVD-writers I can't > test their behaviour regarding the minimum accepted block > size. > > Therefore I'd like to ask you for a little test with > your DVD-RAM enabled DVD-writer. > > 1. Insert a DVD-RAM (not DVD-R or DVD-RW!) > 2. run 'dd if=/dev/acd0 of=/dev/null bs=512 count=1' (please adjust - if > necessary - the device name) > 3. run 'dd if=/dev/acd0 of=/dev/null bs=2048 count=1' (please adjust - if > necessary - the device name) > > Please report me whether command 3 and command 2 succeed > and also if command 3 succeed and command 2 > fails. The first case would mean that your dvd-write is > capable of reading blocks smaller that 2048 bytes which > would be very surprising for me > > If you have an empty DVD-RAM (or an DVD-RAM with un- > important data) I'd pleased if you could also try a > writing test. > > 1. Insert a DVD-RAM (Remark: *it will be deleted*) > 2. run 'dd if=/dev/zero of=/dev/acd0 bs=512 count=1' (please adjust - if > necessary - the device name) > 3. run 'dd if=/dev/zero of=/dev/acd0 bs=2048 count=1' (please adjust - if > necessary - the device name) > > Please report me whether command 3 and command 2 succeed > ans also if command 3 succeed and command 2 fails. > The first would mean that your dvd-write is capable of writing > blocks with 512 bytes. That would mean that the instruction set > of the handbook works for you. > > My output of the reading an writing test is > the following: > > Reading: > > # dd if=/dev/acd0 of=/dev/null bs=512 count=1 > dd: /dev/acd0: Invalid argument > 0+0 records in > 0+0 records out > 0 bytes transferred in 0.000196 secs (0 bytes/sec) > # dd if=/dev/acd0 of=/dev/null bs=2048 count=1 > 1+0 records in > 1+0 records out > 2048 bytes transferred in 1.886969 secs (1085 bytes/sec) > > Writing: > > # dd if=/dev/zero of=/dev/acd0 bs=512 count=1 > dd: /dev/acd0: Invalid argument > 1+0 records in > 0+0 records out > 0 bytes transferred in 0.000205 secs (0 bytes/sec) > # dd if=/dev/zero of=/dev/acd0 bs=2048 count=1 > 1+0 records in > 1+0 records out > 2048 bytes transferred in 0.001600 secs (1280169 bytes/sec) > > You see that my device accept read and writes with > a blocksize (or a multiple of a blocksize) of 2048 bytes > only. > I can not test now, but everything I had seen previously when looking to use DVD-RAM for a live system instead of using hard drive, plus cheaper & easier to backup/replace, points to having a block size of 2048 bytes, even Vista it is the only option and is the default. it works for me perfectly for over a year on a firewall & file server, only thing I changed was the default block/frag size for UFS2 to 8096/1024. Only time I hear them spin-up is when periodic runs daily/weekly/monthly. > Best regards, > Martin Laabs > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to "freebsd-questions-unsubscribe@freebsd.org" > -- Kimi
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