On 12/05/2016 01:22 PM, Tim wrote: > Allegedly, on or about 05 December 2016, John Pilkington sent: >> I don't really understand the wish to use dd for this. > > Because it used to work... And you were very fortunate to have that happen. As many others have pointed out, the CD-R/DVD-R drive must be set up in specific modes to write to it. "...it used to work..." was serendipitous for you as the device was already in a "receptive" mode. However, as kernels and drivers have improved, it's likely that someone noticed that and made the device read-only UNLESS you poke it using the right ioctl() calls to set up the drive for writing. >> I burn dvds from iso several times a week, using k3b in verify mode. >> FWIW the growisofs command it uses is apparently: > > In essence I agree that all that's required is for their to be some > suitable command line instruction for doing the job. It's pretty easy: growisofs -dvd-compat -Z /dev/<devicename>=/path/to/file.iso Why one finds using the proper command instead of "dd" and all the various bizarre options you must specify to try to get it to work is beyond me. dd is not broken. The drivers don't permit arbitrary writes to CD or DVD drives any longer. That is a fact of life you have to live with. I intensely dislike systemd and journalctl, but I have been forced to use them. Learn to use growisofs to write pre-mastered ISO files (and don't get it confused with the mastering program mkisofs). > However, some of the tools are meant for creating the image that will be > burnt from ordinary files. In other words, the tools add in the headers > needed to use the disc (make it bootable, make it recognised as a file > system, etc.). That's what mkisofs does (NOT growisofs). It is essentially an ISO mastering program. It ordinarily does not write ISO files to CD or DVD media unless you specify the device name to the -o flag (not a great idea). mkisofs is normally used to create a .iso file which you later burn to CD/DVD media via growisofs or one of the GUI tools like brasero. > But in some cases, the thing that you want to burn is already > fully-prepared (such as system install ISOs), and adding another wrapper > around that causes problems (if its not smart enough to avoid doing > that). Giving you the ever-annoying situation where the DVD has one > file burnt on it, the original ISO image as one large unusable file. The growisofs command I gave above does precisely that--burn an ISO file to a DVD drive with DVD-R or DVD+R media in it. For a CD or DVD to be readable, it must have an initial session and files written to it (using the "-Z /dev/<devicename>" flags, other mkisofs options and a list of files). growisofs uses mkisofs to create a (transient) image if you do not use the form of the command I gave above (/dev<devicename>=/path/to/file.iso is a special case). You may add additional files if you wish by merging additional files (using the "-M /dev/<devicename>" flags, other mkisofs options and another list of files). Finally, you should close the session by writing some zeroes to the device (using the "-M /dev/<devicename>=/dev/zero" flags with no additional files). Note that doing the above is essentially bypassing the .iso file and mastering directly on media (not a great idea IMHO). It's far easier (and cheaper) to master to a .iso file, then mount it via mount -t iso9660 -o loop /path/to/file.iso /some/mountpoint then "cd /some/mountpoint" and snoop around to investigate whether it's a good image or not. The special case I gave above with -dvd-compat -Z /dev/<devicename>=/path/to/file.iso is used to burn a pre-mastered ISO file to a DVD. It does not invoke mkisofs at all and just burns the ISO image to the media. Read the manpage for growisofs carefully. ---------------------------------------------------------------------- - Rick Stevens, Systems Engineer, AllDigital ricks@xxxxxxxxxxxxxx - - AIM/Skype: therps2 ICQ: 226437340 Yahoo: origrps2 - - - - "And on the seventh day, He exited from append mode." - ---------------------------------------------------------------------- _______________________________________________ users mailing list -- users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to users-leave@xxxxxxxxxxxxxxxxxxxxxxx
