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Re: dd: error reading '/dev/sr0': Input/output error




Hi,

md wrote:
> When copying a dvd to file on the harddrive, I'm getting [...]
> MD> sudo dd if=/dev/sr0 of=/sdb1/movie.iso
> 32596480 bytes (33 MB, 31 MiB) copied, 7.00018 s, 4.7 MB/s
> dd: error reading '/dev/sr0': Input/output error

Do you see fresh messages in the output of dmesg ?
Like

  Dec  2 13:56:33 ... kernel: [...] Sense Key : Medium Error [current]
  Dec  2 13:56:33 ... kernel: [...] Info fld=0x69c0
  Dec  2 13:56:33 ... kernel: [...] sr 2:0:0:0: [sr0]
  Dec  2 13:56:33 ... kernel: [...] Add. Sense: Unrecovered read error
  Dec  2 13:56:33 ... kernel: [...] sr 2:0:0:0: [sr0] CDB:
  Dec  2 13:56:33 ... kernel: [...] Read(10): 28 00 00 00 69 b8 00 00 40 00

What do you get from

  xorriso -outdev /dev/sr0 \
          -check_media use=outdev \
          data_to=/sdb1/movie.udf \
          --

(It will at least show error messages directly.)


Gene Heskett wrote:
> Classic slow spinup.

After 33 MiB of reading ?

(We have a bug in the kernel since 2008 which prevents waiting for the
 drive to become ready after automatic tray loading. But this causes
 0 bytes of read result and lets dd end immediately.)


> You can get a better dvd drive

Read failures of decaying drives often show surprising success-or-error
patterns. Depending on how idvdbackup accesses the drive, its doings
 might be beneficial.
But reading in

  http://manpages.ubuntu.com/manpages/bionic/man1/dvdbackup.1.html
  "-M, --mirror
                 backup the whole DVD"

i'd expect it to read sequentiall, like dd does.

So more questions to md:

- Does a second or third dd run yield success if no dvdbackup was run
  inbetween ?

- Does dvdbackup yield a complete set of files if you let it work
  until it ends on its own ?


Have a nice day :)

Thomas