md5sum of partition and img do not match
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I booted Ubuntu on a live USB and ran:
dd if=/dev/sda1 of=/mnt/usb/backup.img bs=30M oflag=sync
I then performed a comparison (using 'md5sum') of the above input partition and output img, but they did not match. Delving further, I found the img was shorter by 1 byte hence the mismatch! 'cmp' of the two returns "EOF on image".
HDD image file checksum does not match with device checksum mentions that dd stopped at EOF and this is normal behaviour, but I am still unclear on the entire situation...
My questions are:
1- What does EOF means in the context of a partition? I think I understand EOF in the context of a file but this is different as I would expect to find EOF at the end of the partition only.
2- Is restoring the dd img (dd if=/mnt/usb/backup.img if=/dev/sda1) safe?
3- What is in that last byte?
Thanks
linux dd
asked Jan 24 at 21:48
dumb0dumb0
92
add a comment |
I booted Ubuntu on a live USB and ran:
dd if=/dev/sda1 of=/mnt/usb/backup.img bs=30M oflag=sync
I then performed a comparison (using 'md5sum') of the above input partition and output img, but they did not match. Delving further, I found the img was shorter by 1 byte hence the mismatch! 'cmp' of the two returns "EOF on image".
HDD image file checksum does not match with device checksum mentions that dd stopped at EOF and this is normal behaviour, but I am still unclear on the entire situation...
My questions are:
1- What does EOF means in the context of a partition? I think I understand EOF in the context of a file but this is different as I would expect to find EOF at the end of the partition only.
2- Is restoring the dd img (dd if=/mnt/usb/backup.img if=/dev/sda1) safe?
3- What is in that last byte?
Thanks
linux dd
asked Jan 24 at 21:48
dumb0dumb0
92
shorter by 1 byte? how did you determine that? commands and outputs? - linked question is about the other direction, not your issue.
– frostschutz
Jan 24 at 21:56
"blockdev --getsize64 /mnt/usb/backup.img" reported one less byte than "blockdev --getsize64 /dev/sda1"
– dumb0
Jan 24 at 22:02
The linked question seems very different. In that case the partition contains stuff beyond the end of the image. But in your case if you did partition → image, then I would expect them to match.
– ctrl-alt-delor
Jan 24 at 22:21
add a comment |
I booted Ubuntu on a live USB and ran:
dd if=/dev/sda1 of=/mnt/usb/backup.img bs=30M oflag=sync
I then performed a comparison (using 'md5sum') of the above input partition and output img, but they did not match. Delving further, I found the img was shorter by 1 byte hence the mismatch! 'cmp' of the two returns "EOF on image".
HDD image file checksum does not match with device checksum mentions that dd stopped at EOF and this is normal behaviour, but I am still unclear on the entire situation...
My questions are:
1- What does EOF means in the context of a partition? I think I understand EOF in the context of a file but this is different as I would expect to find EOF at the end of the partition only.
2- Is restoring the dd img (dd if=/mnt/usb/backup.img if=/dev/sda1) safe?
3- What is in that last byte?
Thanks
linux dd
asked Jan 24 at 21:48
dumb0dumb0
92
I booted Ubuntu on a live USB and ran:
dd if=/dev/sda1 of=/mnt/usb/backup.img bs=30M oflag=sync
I then performed a comparison (using 'md5sum') of the above input partition and output img, but they did not match. Delving further, I found the img was shorter by 1 byte hence the mismatch! 'cmp' of the two returns "EOF on image".
HDD image file checksum does not match with device checksum mentions that dd stopped at EOF and this is normal behaviour, but I am still unclear on the entire situation...
My questions are:
1- What does EOF means in the context of a partition? I think I understand EOF in the context of a file but this is different as I would expect to find EOF at the end of the partition only.
2- Is restoring the dd img (dd if=/mnt/usb/backup.img if=/dev/sda1) safe?
3- What is in that last byte?
Thanks
linux dd
linux dd
asked Jan 24 at 21:48
dumb0dumb0
92
asked Jan 24 at 21:48
dumb0dumb0
92
asked Jan 24 at 21:48
dumb0dumb0
92
asked Jan 24 at 21:48
dumb0dumb0
92
asked Jan 24 at 21:48
dumb0dumb0
92
92
shorter by 1 byte? how did you determine that? commands and outputs? - linked question is about the other direction, not your issue.
– frostschutz
Jan 24 at 21:56
"blockdev --getsize64 /mnt/usb/backup.img" reported one less byte than "blockdev --getsize64 /dev/sda1"
– dumb0
Jan 24 at 22:02
The linked question seems very different. In that case the partition contains stuff beyond the end of the image. But in your case if you did partition → image, then I would expect them to match.
– ctrl-alt-delor
Jan 24 at 22:21
add a comment |
shorter by 1 byte? how did you determine that? commands and outputs? - linked question is about the other direction, not your issue.
– frostschutz
Jan 24 at 21:56
"blockdev --getsize64 /mnt/usb/backup.img" reported one less byte than "blockdev --getsize64 /dev/sda1"
– dumb0
Jan 24 at 22:02
The linked question seems very different. In that case the partition contains stuff beyond the end of the image. But in your case if you did partition → image, then I would expect them to match.
– ctrl-alt-delor
Jan 24 at 22:21
shorter by 1 byte? how did you determine that? commands and outputs? - linked question is about the other direction, not your issue.
– frostschutz
Jan 24 at 21:56
shorter by 1 byte? how did you determine that? commands and outputs? - linked question is about the other direction, not your issue.
– frostschutz
Jan 24 at 21:56
"blockdev --getsize64 /mnt/usb/backup.img" reported one less byte than "blockdev --getsize64 /dev/sda1"
– dumb0
Jan 24 at 22:02
"blockdev --getsize64 /mnt/usb/backup.img" reported one less byte than "blockdev --getsize64 /dev/sda1"
– dumb0
Jan 24 at 22:02
The linked question seems very different. In that case the partition contains stuff beyond the end of the image. But in your case if you did partition → image, then I would expect them to match.
– ctrl-alt-delor
Jan 24 at 22:21
The linked question seems very different. In that case the partition contains stuff beyond the end of the image. But in your case if you did partition → image, then I would expect them to match.
– ctrl-alt-delor
Jan 24 at 22:21
add a comment |
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shorter by 1 byte? how did you determine that? commands and outputs? - linked question is about the other direction, not your issue.
– frostschutz
Jan 24 at 21:56
"blockdev --getsize64 /mnt/usb/backup.img" reported one less byte than "blockdev --getsize64 /dev/sda1"
– dumb0
Jan 24 at 22:02
The linked question seems very different. In that case the partition contains stuff beyond the end of the image. But in your case if you did partition → image, then I would expect them to match.
– ctrl-alt-delor
Jan 24 at 22:21