On Fri, 5 May 2006, houghi wrote:
On Thu, May 04, 2006 at 01:54:48AM +0200, houghi wrote:
SUSE uses tagmedia to check the media. I used the following command (and outcome) houghi@penne : tagmedia --md5 --pad 150 --check \ ~/iso/10.1_RC3/DVD_DIR/SUSE-10.1-0-DVD.iso md5sum=99b7d0c508d213aa0c9ab6edfad56ef1 pad=150 check=1
OK. I figured out why it did not work several times and why it suddenly worked. The answer is not in the README but is in the /usr/bin/tagmedia script: # md5sum is calculated assuming all spaces in that area.
So what happend was the first time I did just `tagmedia --md5` and that was not good. I then did a `tagmedia --md5 --pad 150 --check` wwhich is the correct command, but I had not removed (all of) the tags, so it was not all spaces.
That, again, is not true either. ;-) You don't have to remove any tags or such. It is ok to re-run tagmedia with any combination of tags you want.
No idea what the --pad does, but it seems to work. The SUSE iso's have it, so why not mine. :-)
So now we are at the heart of the problem. You should have mentioned that earlier. :-) --pad=150 says to _NOT_ verify the last 150 sectors (that is, 300k) of the iso. Instead, checkmedia assumes them to be all zero without actually reading them. The reason is that many CD-drives have problems reading the last sectors of an iso. So, our CDs are created with an additional padding (= extra sectors) at the end of the iso (150 sectors, as you might have guessed at this point). You need to match the --pad given to tagmedia with what you give to mkisofs and things should be fine. If not, checkmedia will return an md5sum error. Steffen