Hi,
> by closed, you mean the xorriso-burned DVD can no longer be written to,
> correct?
Yes. A DVD+R can have three states: Blank, Appendable, Closed.
Blank means it is yet unused. Appendable means that it contains data and
still can take another burn run ("session"). Closed means that it cannot
be written any more.
CD-RW and unformatted DVD-RW can be blanked to become writable from scratch
again. CD-R, DVD-R, DVD+R, BD-R stay closed forever. DVD-RAM, DVD+RW, BD-RE,
formatted DVD-RW, formatted CD-RW can be overwritten without blanking,
because they are in the fourth possible state: Overwritable.
> So, what do you think the problem was, a malfunctioning CD/DVD drive?
Obviously. Now the question is: Does it just have some dust on the lense
or is it entirely dead. A good blow with pressured air into the open
drive might work wonders.
--------------------------------------------------------------------------
As for checkreading, i would propose to read the plain DVD+R content instead
of mounting it and checking its files. If the overall image is ok, the files
can hardly be damaged. (libmath says 0 if i try to estimate the probability.
Well, numerical math is always a bit optimistic.)
It is important to read only as many blocks from the DVD as the original
ISO image has. Else the checksum will hardly match.
Code:
blocks=$(expr $(stat -c '%s' ubuntu-18.04.3-desktop-amd64.iso) / 2048)
dd if=/dev/sr1 bs=2048 count=$blocks | md5sum
Compare the resultiing hex number with the hex number in line
Code:
72491db7ef6f3cd4b085b9fe1f232345 *ubuntu-18.04.3-desktop-amd64.iso
of http://releases.ubuntu.com/18.04/MD5SUMS
> I don't know what a non-matching md5sum looks like.
It will be just some string of 32 hex digits [0-9a-f] which is not the same
as the one you expect. E.g. "hallo\n" has this MD5:
Code:
$ echo hallo | md5sum
aee97cb3ad288ef0add6c6b5b5fae48a -
If you are insecure about comparing 32 digits, let the shell do it for you:
Code:
$ test 72491db7ef6f3cd4b085b9fe1f232345 = 72491db7ef6f3cd4b085b9fe1f232345 && echo OK
OK
$ test 72491db7ef6f3cd4b085b9fe1f232345 = 72491db7ef6f3cd4b085b9fe1f232340 && echo OK
$
(I.e. chirping crickets are a negative outcome.)
Have a nice day
Thomas
Bookmarks