On 23 May 2010, at 15:31, Manolis Kiagias wrote:

> On 24/05/2010 1:23 π.μ., Doug Hardie wrote:
>> I am periodically backing up a bunch of files to DVD.  I use mkisofs to 
>> create the original image and growisofs to write it to a real DVD.  However, 
>> at that point I want to verify that the write was successful.  I tried using 
>> dd to read back in the DVD to a file.  Its interesting that the bs parameter 
>> must be at least 2048 or dd complains about a parameter error.  However, the 
>> big issues is that the original image file is shorter than the read file.  
>> The difference is 10240  bytes.  This difference is the same for bs 2048, 
>> 10240, or 102400.  It appears that dd is adding one last block.  Is there a 
>> way to prevent this or remove that block?
> Use the count= parameter in dd to read the exact count of blocks in the
> DVD. Use isoinfo to obtain this information from the media itself. Have
> a look at the instructions here:
> http://www.troubleshooters.com/linux/coasterless.htm

Thanks.  That works great.  I did discover that appending 10240 zeros to the 
end of the original iso file also works.  However, I am not convinced that it 
will always be that value.  The approach above should be more 
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