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3-22] How can I be sure the data was written correctly?




Description

This article is from the CD-Recordable FAQ, by Andy McFadden (fadden@fadden.com) with numerous contributions by others.

3-22] How can I be sure the data was written correctly?

(2002/12/10)

The easiest way is to compare the original with the copy. Some programs,
such as recent versions of Nero, will automatically compare the disc
contents with the original files. You can also use something like CD-R
Verifier from http://www.cdrom-prod.com/cd-r_verifier.html or CDCchedk
from http://Fusion.zejn.si/ to check the contents of an entire CD-ROM easily.

Another way is to do a recursive file-by-file comparison. Programs that
compute CRCs on files and then compare them (often used for virus-checking)
will work.

One way to do this is with use the UNIX "diff" utility, which is
available for Windows (along with many other similar utilities) from
http://www.reedkotler.com/. If you had copied the contents of C:\MyData
onto a CD-R at E:\, you would use:

diff -q -r C:\MyData E:

The "-q" flag tells it to report if the files differ, but not show what
the differences are, and the "-r" flag says to descend into directories
recursively.

There are many other options. A utility called "treediff", available
from the Simtel archives (http://www.simtel.com/), may be helpful.
http://www.funduc.com/directory_toolkit.htm has a shareware program with
some relevant features. http://www.araxis.com/ has an evaluation copy
of PMdiff, available for Windows and native OS/2. You can get "FileSync"
from http://www.fileware.co.uk/.

You can also use Microsoft's WinDiff, which -- unlike some of the
programs mentioned earlier -- understands long filenames. It can be
found on Microsoft's recent operating system discs, e.g. on Win98 it
lives in \tools\reskit\file\windiff.exe. It used to be available for
download from ftp.microsoft.com, but they rearrange that site frequently,
so there's not much point in including a URL.

An alternative to windiff is xdiff, from http://www.wookie.demon.co.uk/xdiff/.

Rocksoft Pty has a product called Veracity (http://www.veracity.com/) that
can check the integrity of a directory tree.

Visit http://www.fuw.edu.pl/~jt/cdvfy/ for some shell scripts that will
compute MD5 checksums on a tree. Under Windows, try Advanced CheckSum
Verifier from http://www.irnis.net/ for MD5 and CRC32, or md5summer
from http://www.md5summer.org/.

If you *really* want to verify your discs, try http://www.audiodev.com/.


 

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