md5sum Hard drive vs CD-ROM puzzle
Sorry for posting this in HTLM format. Here it is in plain text:
In order to burn the 2 CD i386 binary set of 2.1r3 I ftp'd the images to my
Win98 machine as I don't currently have a CD burner in my Linux box. I have
successfully used these CD's to create Linux systems. These CD's were
burned using EZ CD Creator using image mode. But because I have limited
storage on my Win98 machine I also burned the image files, binary-i386-1.iso
and binary-i386-2.iso in file mode to two CD's so that I could delete them
from my hard drive and restore them later should I wish. After burning them
to the CD's I did a byte by byte comparison of the CD's vs the disk files on
my Win98 machine using DOS command fc/b and found them to be identical.
Being properly paranoid I wanted a 'second opinion' which I could get by
running md5sum on the files. The md5sum is provided on the various mirror
sites for the disk images. I needed to get the files to my Linux machine to
run md5sum.
So I took the first CD, which contained the file binary-i386-1.iso and
copied is from my CD reader on my Linux machine to my home directory on my
hard drive. I ran md5sum on the hard drive file and obtain the correct
checksum, as is reported in the file MD5SUMS.txt. I am thus confident that
the file I now have on my hard drive is identical to the file I ftp'd from
the mirror site to my Win98 machine, burned on a CD-ROM, carried to my Linux
machine etc...
But when I run md5sum against the same file on the CD-ROM I get a different
md5sum!!
So from my home directory I ran cmp binary-i386-1.iso
/cdrom/binary-i386-1.iso and no differences are found between the files.
I have repeated this process several times, its entirely reproducible.
Two identical files produce different md5sums! How can this be?
Ron
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