>No module ide-scsi governing the writer either ? > > ide-scsi is enabled for the DVD writer. I haven't yet experimented with writing without the use of this kernel option.
>>DVD-RAM discs can have an arbitrary filesystem placed on them and be >>mounted. eg. >> # mke2fs /dev/cdrom >> # mount -t ext2 /dev/cdrom /cdrom >> # cp * /cdrom >> >> > >I tried that with Panasonic LM-AF120U3 media. >Seems not to work reliably with ide-scsi (MD5 errors >when verifying content of a file), is darn slow and >larger backups clogg the i/o buffers which then >cannot be used for hard disk i/o. > >Do you get better results without ide-scsi ? > I haven't yet tried using DVD-RAM like this without ide-scsi. However I have just written 2.7 GB of data to a Maxell DVD-RAM using this method with no errors, and an average transfer rate of 1.99 MB/s.
>It appears a similar method can also be used with DVD+RW discs, however >I have also tried writing binary streams to DVD+RW discs. For example > # umount /cdrom > # tar -Mcvf /dev/cdrom /some/files > I don't understand why this works, but the resultant disc appears to be > verbatim. > I have double checked this, and was able to get an average transfer rate of 3.1 MB/s with no errors.
>Now if you dump just a raw file to the media > cat /my/fat_file >/dev/cdrom >and compare it with the original > diff /my/fat_file /dev/cdrom 2>&1 | less >does it really match ? (At least up to the >length of /my/fat_file) > > This seems to work fine. I copied a 1.2 GB file to a DVD+RW using this method, and it verified OK. This technique gave an average data transfer rate of 3.1 MB/s.
>I am willing to bet that you cannot mount >on Linux a DVD written with tar cf /dev/cdrom > > This makes sense. It's hard to mount a non-existant file system. :)
>I am still a bit in doubt about the >general usability of your writing method. >My approach would be > tar cvzf - /some/files | \ > growisofs -use-the-force-luke -Z /dev/sr0=/proc/self/fd/0 > >(tar option -M is still a bit obscure to me after >reading man and info tar. Is it about end-of-tape >handling ?) > > Although using growisofs in that manner is probably a more comaptible and reliable method, the main problem is that it can not readily split the image across multiple DVDs on-the-fly, as far as I am aware. The -M option of tar is to allow a tar file/stream to be split across multiple volumes. Thus when the end of a tape is reached, a new tape can be inserted and writing can continue. The M option appears to work when writing to DVD as well, although I haven't yet tried it with growisofs. Thus # tar -Mcvf /dev/cdrom /some/files will split the tar file across multiple DVDs if necessary. It's a bit of a hack, but it seems to work. Also I can't seem to get growisofs to write faster than 1x. But that's another problem altogether...
Lee
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