On 2 March 2014 20:41, Andrei POPESCU <andreimpope...@gmail.com> wrote: > On Sb, 01 mar 14, 14:38:14, Richard Owlett wrote: >> >> root@minimal-squeeze:/home/richard# isoinfo -d -i /dev/cdrom > ... >> Volume size is: 1939608 >> root@minimal-squeeze:/home/richard# dd if=/dev/cdrom bs=2048 >> count=1939608 of=/home/richard/myiso1.iso conv=notrunc >> 1939608+0 records in >> 1939608+0 records out >> 3972317184 bytes (4.0 GB) copied, 711.022 s, 5.6 MB/s > > Ok. Did you try to md5sum the image file? You can compare that to the > md5sum of the DVD. > >> root@minimal-squeeze:/home/richard# dd if=/home/richard/myiso1.iso >> bs=2048 count=1939608 of=/dev/sdb conv=notrunc >> 1939608+0 records in >> 1939608+0 records out >> 3972317184 bytes (4.0 GB) copied, 1591.35 s, 2.5 MB/s > > Not sure if this makes a differences, but why the count= and conv= ?
Richard is using count and conv because I pointed him to the instructions here: http://www.debian.org/doc/manuals/debian-reference/ch09.en.html#_making_the_iso9660_image_file Those instructions require the count and notrunc, with this warning: "You must carefully avoid ISO9660 filesystem read ahead bug of Linux as above to get the right result." The above is Richard showing that he complied with those instructions. I would like to have more information about this "read ahead bug", but I cannot find a full bug report or similar technical discussion of it. Thomas states that "Debian i386 images are ISO 9660 filesystems" so I assume that this bug workaround is still required for them. The best information I can find is this recent post by Thomas. http://askubuntu.com/questions/408224/the-file-casper-filesystem-squashfs-is-corrupt/410492#410492 Thomas thank you for the information you already posted, I found it very interesting. Can you recommend anywhere I can read to learn more about the Debian DVD filesystems? Apart from searching for your past emails and forum posts :) And where can I learn more about the read-ahead bug: how to identify it, how to avoid it, is there a bug tracker for it, which if any source file will eventually contain a fix for it? Does it also affect udf file systems? -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: https://lists.debian.org/CAMPXz=qJE7asHZuA2bO49K6pHWqvxNxmDbYEL3N+Gcw=6a1...@mail.gmail.com
