I think that's basically what this rawread tools does. Rawread is just a script that uses isoinfo to get the correct block sizes for the cd. The usage given on the website is: rawread /dev/cdrom > cdrom.iso rawread /dev/cdrom |md5sum md5sum cdrom.iso
Cory On Mon, Feb 24, 2003 at 04:20:27PM -0800, Tim Howe wrote: > One way to be more careful (Using OpenBSD anyway, I have no Linux experience with > this) is to read the CD first... > > $ disklabel /dev/cd0c > > Among a mess of other data you will see something like... > > total sectors: 58578 > > You can use this knowledge to correctly dump the image... > > dd if=/dev/rcd0c of=image.raw bs=2048 count=58578 > > When I was really being paranoid, I would burn a CD from this image, dump it again > and compare md5sums. I have been using this exact method for almost 2 years without > any problems that I can remember. > > --TimH > > On Mon, 24 Feb 2003 15:55:25 -0800 > Cory Petkovsek <[EMAIL PROTECTED]> wrote: > > > On Mon, Feb 24, 2003 at 03:45:27PM -0800, Tim Howe wrote: > > > Doesn't cmp work? > > > > > > I ussually verify my OpenBSD boot floppies like so... > > > > > > $ cmp floppy33.fs /dev/fd0a > > > > > > Shouldn't this work for CDs and ISOs? > > > > > > --TimH > > > > I though so as well. If that were the case the isoinfo tool is not > > necessary and one could make a disk image like this: > > cp /dev/sr0 cdrom.img > > or > > cat /dev/sr0 > cdrom.img > > > > However looking at the webpage it states: > > http://www.troubleshooters.com/linux/coasterless.htm#_Accurately_Reading_a_CD > > > > ... when you test your newly burned CD with md5sum, the data you read from > > /dev/cdrom must be accurate, or you'll get a false error alarm. Also, many CD's > > are burned off ISO images created from other CDs. If those original CD's were > > read incorrectly, then the resulting ISO's are incorrect, and every > > duplicate made from those ISO's is incorrect. Accurate CD reading is essential. > > > > Most bad CD device reads are caused by either: > > > > 1. Reading too few or two many blocks of the CD device > > 2. Inability to read the last block. > > > > This section explains how to consistently read the correct number of blocks. > > The only reliable method I've found to find the true end of the CD is with > > the isoinfo utility. > > -------- > > > > Cory > > > > > > > On Mon, 24 Feb 2003 08:57:04 -0800 (PST) > > > Dave Wyatt <[EMAIL PROTECTED]> wrote: > > > > > > > Google is your friend! > > > > I was going to post the question below, but found this > > > > on Google: > > > > > > > > http://www.troubleshooters.com/linux/coasterless.htm#rawread > > > > > > > > Any Comments? > > > > > > > > > > > > Short question: > > > > > > > > How can I verify or compare an ISO that I created from > > > > a known good CD? > > > > > > > > > > > > Long question: > > > > > > > > I created ISOs for Red Hat 8.0 from CDs I burnt from > > > > downloaded ISOs which checked good with the md5sums > > > > after downloading. After burning them, the CDs > > > > checked good with Red Hats checkmedia, so these are > > > > *my originals* that I wanted to make copies of for my > > > > son. I no longer have the downloaded ISOs. > > > > > > > > I did the > > > > > > > > dd if=/dev/cdrom of=RedHatDiskx.iso > > > > > > > > thing and created the ISOs. I then burned the CDs and > > > > began the checkmedia routine. CDs 1 and 2 passed and I > > > > wasn't going to check the rest but did anyway. CDs 3-5 > > > > failed checkmedia. I then re-checked the originals > > > > and they all passed checkmedia. So I ended up with 3 > > > > coasters, which isn't a > > > > > > > > big deal but pretty annoying. > > > > > > > > I looked at man dd and man md5sum. I don't see any > > > > way to verify with dd or to create md5sums from a data > > > > CD. Did I miss something? Is there a way to verify > > > > that an ISO created with dd is valid? Or that a CD > > > > burned from an ISO is good? > > > > > > > > BTW, if it makes any difference, the versions are: > > > > > > > > md5sum (textutils) 2.1 > > > > dd (fileutils) 4.1.11 > > > > > > > > on a SuSE 8.1 system. > > > > > > > > Dave > > > > > > > > > > > > __________________________________________________ > > > > Do you Yahoo!? > > > > Yahoo! Tax Center - forms, calculators, tips, more > > > > http://taxes.yahoo.com/ > > > > _______________________________________________ > > > > Eug-LUG mailing list > > > > [EMAIL PROTECTED] > > > > http://mailman.efn.org/cgi-bin/listinfo/eug-lug > > > _______________________________________________ > > > Eug-LUG mailing list > > > [EMAIL PROTECTED] > > > http://mailman.efn.org/cgi-bin/listinfo/eug-lug > > _______________________________________________ > > Eug-LUG mailing list > > [EMAIL PROTECTED] > > http://mailman.efn.org/cgi-bin/listinfo/eug-lug > _______________________________________________ > Eug-LUG mailing list > [EMAIL PROTECTED] > http://mailman.efn.org/cgi-bin/listinfo/eug-lug _______________________________________________ Eug-LUG mailing list [EMAIL PROTECTED] http://mailman.efn.org/cgi-bin/listinfo/eug-lug
