<br><br><div class="gmail_quote">On Sat, Oct 2, 2010 at 4:40 AM, Andre Robatino <span dir="ltr"><<a href="mailto:robatino@fedoraproject.org">robatino@fedoraproject.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
JD <jd1008 <at> <a href="http://gmail.com" target="_blank">gmail.com</a>> writes:<br>
<br>
> I burned Fedora-14-Beta-i386-DVD.iso to blank dvd.<br>
> One time I used wodim, and 2nd time I used growisofs.<br>
> After each burn, I would dd the dvd back in:<br>
><br>
> dd if=/dev/sr0 of=f14.iso bs=2k<br>
><br>
> In both cases the size of f14.iso was 10240 bytes larger than<br>
> Fedora-14-Beta-i386-DVD.iso.<br>
<br>
In general this won't work unless dd is told exactly how much to read off.<br>
Unfortunately, it works often enough that people think it's supposed to. Use the<br>
rawread script from<br>
<br>
<a href="http://www.troubleshooters.com/linux/coasterless.htm#rawread" target="_blank">http://www.troubleshooters.com/linux/coasterless.htm#rawread</a><br>
<br>
instead. This determines the ISO size from the ISO header and then automatically<br>
reads off the right amount.<br>
<br>
There is a defect in the Live and netinst images (which started in F12 Alpha,<br>
and only affected i386 and x86_64, not ppc), in that they are larger than the<br>
ISO header indicates:<br>
<br>
<a href="https://bugzilla.redhat.com/show_bug.cgi?id=585006" target="_blank">https://bugzilla.redhat.com/show_bug.cgi?id=585006</a><br>
<br>
To read these off properly, the rawread script won't work, since it assumes that<br>
the ISO header size is correct. Instead, you have to manually compose a dd<br>
command that reads off the size corresponding to the actual ISO file (not the<br>
size in the ISO header).<br></blockquote><div><br>One can also tell dd to read by single physical layer sectors using the "bs=2048"<br>option. This may increase the read time a bit, but generally results in s more consistent<br>
chance of getting the correct size.<br><br>-- <br>G.Wolfe Woodbury<br> <br></div></div>