md5sum of /dev/sr1 different than ISO image?
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After writing an ISO image using Brasero, I discovered that the md5sum of the target DVD is different than the ISO image, despite no readability errors.
What has caused that difference?
iso hashsum dvd brasero
edited Mar 11 at 2:25
Jeff Schaller♦
44.7k1163145
asked Mar 11 at 0:56
neverMind9neverMind9
660319
|
show 4 more comments
2
After writing an ISO image using Brasero, I discovered that the md5sum of the target DVD is different than the ISO image, despite no readability errors.
What has caused that difference?
iso hashsum dvd brasero
edited Mar 11 at 2:25
Jeff Schaller♦
44.7k1163145
asked Mar 11 at 0:56
neverMind9neverMind9
660319
3
Your ISO image is smaller than the capacity of DVD? The rest might be read as zero, which might be reason cause the hashsum difference.
– 炸鱼薯条德里克
Mar 11 at 2:15
1
Maybe brasero created another image, with the iso as a file contained in it? I've always used growisofs and cdrecord directly, and the checksum always matched, unless there was some error.
– Uncle Billy
Mar 11 at 8:54
@炸鱼薯条德里克 have you actually tried that? your comment is completely off.
– Uncle Billy
Mar 11 at 9:02
1
In cases like this, I runcmp -l known-good.iso /dev/sr1. It's OK if there's an error message saying the first file is shorter. To be more thorough, you could try(cat known-good.iso /dev/zero) | cmp -l - /dev/sr1and see if the error output by cmp is about the second file being shorter.
– Mark Plotnick
Mar 11 at 18:49
1
@neverMind9 maybe it's trying to close/finalize (or unclose) the last session? (that results in the TOC on the disc being different from the TOC part of the iso image). Unfortunately, I'm not able to test anything right now.
– Uncle Billy
Mar 11 at 19:39
|
show 4 more comments
2
2
2
After writing an ISO image using Brasero, I discovered that the md5sum of the target DVD is different than the ISO image, despite no readability errors.
What has caused that difference?
iso hashsum dvd brasero
edited Mar 11 at 2:25
Jeff Schaller♦
44.7k1163145
asked Mar 11 at 0:56
neverMind9neverMind9
660319
After writing an ISO image using Brasero, I discovered that the md5sum of the target DVD is different than the ISO image, despite no readability errors.
What has caused that difference?
iso hashsum dvd brasero
iso hashsum dvd brasero
edited Mar 11 at 2:25
Jeff Schaller♦
44.7k1163145
asked Mar 11 at 0:56
neverMind9neverMind9
660319
edited Mar 11 at 2:25
Jeff Schaller♦
44.7k1163145
asked Mar 11 at 0:56
neverMind9neverMind9
660319
edited Mar 11 at 2:25
Jeff Schaller♦
44.7k1163145
edited Mar 11 at 2:25
Jeff Schaller♦
44.7k1163145
edited Mar 11 at 2:25
Jeff Schaller♦
44.7k1163145
44.7k1163145
asked Mar 11 at 0:56
neverMind9neverMind9
660319
asked Mar 11 at 0:56
neverMind9neverMind9
660319
asked Mar 11 at 0:56
neverMind9neverMind9
660319
660319
3
Your ISO image is smaller than the capacity of DVD? The rest might be read as zero, which might be reason cause the hashsum difference.
– 炸鱼薯条德里克
Mar 11 at 2:15
1
Maybe brasero created another image, with the iso as a file contained in it? I've always used growisofs and cdrecord directly, and the checksum always matched, unless there was some error.
– Uncle Billy
Mar 11 at 8:54
@炸鱼薯条德里克 have you actually tried that? your comment is completely off.
– Uncle Billy
Mar 11 at 9:02
1
In cases like this, I runcmp -l known-good.iso /dev/sr1. It's OK if there's an error message saying the first file is shorter. To be more thorough, you could try(cat known-good.iso /dev/zero) | cmp -l - /dev/sr1and see if the error output by cmp is about the second file being shorter.
– Mark Plotnick
Mar 11 at 18:49
1
@neverMind9 maybe it's trying to close/finalize (or unclose) the last session? (that results in the TOC on the disc being different from the TOC part of the iso image). Unfortunately, I'm not able to test anything right now.
– Uncle Billy
Mar 11 at 19:39
|
show 4 more comments
3
Your ISO image is smaller than the capacity of DVD? The rest might be read as zero, which might be reason cause the hashsum difference.
– 炸鱼薯条德里克
Mar 11 at 2:15
1
Maybe brasero created another image, with the iso as a file contained in it? I've always used growisofs and cdrecord directly, and the checksum always matched, unless there was some error.
– Uncle Billy
Mar 11 at 8:54
@炸鱼薯条德里克 have you actually tried that? your comment is completely off.
– Uncle Billy
Mar 11 at 9:02
1
In cases like this, I runcmp -l known-good.iso /dev/sr1. It's OK if there's an error message saying the first file is shorter. To be more thorough, you could try(cat known-good.iso /dev/zero) | cmp -l - /dev/sr1and see if the error output by cmp is about the second file being shorter.
– Mark Plotnick
Mar 11 at 18:49
1
@neverMind9 maybe it's trying to close/finalize (or unclose) the last session? (that results in the TOC on the disc being different from the TOC part of the iso image). Unfortunately, I'm not able to test anything right now.
– Uncle Billy
Mar 11 at 19:39
3
3
Your ISO image is smaller than the capacity of DVD? The rest might be read as zero, which might be reason cause the hashsum difference.
– 炸鱼薯条德里克
Mar 11 at 2:15
Your ISO image is smaller than the capacity of DVD? The rest might be read as zero, which might be reason cause the hashsum difference.
– 炸鱼薯条德里克
Mar 11 at 2:15
1
1
Maybe brasero created another image, with the iso as a file contained in it? I've always used growisofs and cdrecord directly, and the checksum always matched, unless there was some error.
– Uncle Billy
Mar 11 at 8:54
Maybe brasero created another image, with the iso as a file contained in it? I've always used growisofs and cdrecord directly, and the checksum always matched, unless there was some error.
– Uncle Billy
Mar 11 at 8:54
@炸鱼薯条德里克 have you actually tried that? your comment is completely off.
– Uncle Billy
Mar 11 at 9:02
@炸鱼薯条德里克 have you actually tried that? your comment is completely off.
– Uncle Billy
Mar 11 at 9:02
1
1
In cases like this, I run
cmp -l known-good.iso /dev/sr1 . It's OK if there's an error message saying the first file is shorter. To be more thorough, you could try (cat known-good.iso /dev/zero) | cmp -l - /dev/sr1 and see if the error output by cmp is about the second file being shorter.– Mark Plotnick
Mar 11 at 18:49
In cases like this, I run
cmp -l known-good.iso /dev/sr1 . It's OK if there's an error message saying the first file is shorter. To be more thorough, you could try (cat known-good.iso /dev/zero) | cmp -l - /dev/sr1 and see if the error output by cmp is about the second file being shorter.– Mark Plotnick
Mar 11 at 18:49
1
1
@neverMind9 maybe it's trying to close/finalize (or unclose) the last session? (that results in the TOC on the disc being different from the TOC part of the iso image). Unfortunately, I'm not able to test anything right now.
– Uncle Billy
Mar 11 at 19:39
@neverMind9 maybe it's trying to close/finalize (or unclose) the last session? (that results in the TOC on the disc being different from the TOC part of the iso image). Unfortunately, I'm not able to test anything right now.
– Uncle Billy
Mar 11 at 19:39
|
show 4 more comments
1 Answer
1
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oldest
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2
When you do this kind of verification , md5sum or sha1sum you must be sure that your reading the same amount of data .
stat --printf '%sn' file.iso
blockdev --getsize64 /dev/sr1
if the data does have the size , you must compute on the smallest size .
to do this :
dd if=file.iso bs=2k count=9000 | md5sum
dd if=/dev/sr1 bs=2k count=9000 | md5sum
answered Mar 11 at 4:07
EchoMike444EchoMike444
1,0506
In that case, both have the same MD5.
– neverMind9
Mar 11 at 20:24
add a comment |
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When you do this kind of verification , md5sum or sha1sum you must be sure that your reading the same amount of data .
stat --printf '%sn' file.iso
blockdev --getsize64 /dev/sr1
if the data does have the size , you must compute on the smallest size .
to do this :
dd if=file.iso bs=2k count=9000 | md5sum
dd if=/dev/sr1 bs=2k count=9000 | md5sum
answered Mar 11 at 4:07
EchoMike444EchoMike444
1,0506
In that case, both have the same MD5.
– neverMind9
Mar 11 at 20:24
add a comment |
2
When you do this kind of verification , md5sum or sha1sum you must be sure that your reading the same amount of data .
stat --printf '%sn' file.iso
blockdev --getsize64 /dev/sr1
if the data does have the size , you must compute on the smallest size .
to do this :
dd if=file.iso bs=2k count=9000 | md5sum
dd if=/dev/sr1 bs=2k count=9000 | md5sum
answered Mar 11 at 4:07
EchoMike444EchoMike444
1,0506
In that case, both have the same MD5.
– neverMind9
Mar 11 at 20:24
add a comment |
2
2
2
When you do this kind of verification , md5sum or sha1sum you must be sure that your reading the same amount of data .
stat --printf '%sn' file.iso
blockdev --getsize64 /dev/sr1
if the data does have the size , you must compute on the smallest size .
to do this :
dd if=file.iso bs=2k count=9000 | md5sum
dd if=/dev/sr1 bs=2k count=9000 | md5sum
answered Mar 11 at 4:07
EchoMike444EchoMike444
1,0506
When you do this kind of verification , md5sum or sha1sum you must be sure that your reading the same amount of data .
stat --printf '%sn' file.iso
blockdev --getsize64 /dev/sr1
if the data does have the size , you must compute on the smallest size .
to do this :
dd if=file.iso bs=2k count=9000 | md5sum
dd if=/dev/sr1 bs=2k count=9000 | md5sum
answered Mar 11 at 4:07
EchoMike444EchoMike444
1,0506
answered Mar 11 at 4:07
EchoMike444EchoMike444
1,0506
answered Mar 11 at 4:07
EchoMike444EchoMike444
1,0506
answered Mar 11 at 4:07
EchoMike444EchoMike444
1,0506
1,0506
In that case, both have the same MD5.
– neverMind9
Mar 11 at 20:24
add a comment |
In that case, both have the same MD5.
– neverMind9
Mar 11 at 20:24
In that case, both have the same MD5.
– neverMind9
Mar 11 at 20:24
In that case, both have the same MD5.
– neverMind9
Mar 11 at 20:24
add a comment |
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3
Your ISO image is smaller than the capacity of DVD? The rest might be read as zero, which might be reason cause the hashsum difference.
– 炸鱼薯条德里克
Mar 11 at 2:15
1
Maybe brasero created another image, with the iso as a file contained in it? I've always used growisofs and cdrecord directly, and the checksum always matched, unless there was some error.
– Uncle Billy
Mar 11 at 8:54
@炸鱼薯条德里克 have you actually tried that? your comment is completely off.
– Uncle Billy
Mar 11 at 9:02
1
In cases like this, I run
cmp -l known-good.iso /dev/sr1. It's OK if there's an error message saying the first file is shorter. To be more thorough, you could try(cat known-good.iso /dev/zero) | cmp -l - /dev/sr1and see if the error output by cmp is about the second file being shorter.– Mark Plotnick
Mar 11 at 18:49
1
@neverMind9 maybe it's trying to close/finalize (or unclose) the last session? (that results in the TOC on the disc being different from the TOC part of the iso image). Unfortunately, I'm not able to test anything right now.
– Uncle Billy
Mar 11 at 19:39