dd command to copy a cd to a hard disk - Input/output error

Rodney Peters rpeters at pcug.org.au
Tue Apr 2 11:33:18 EST 2002

On Monday 01 April 2002 22:17, Daniel <cottmain at yahoo.com.au> wrote
Subject: Re: dd command to copy a cd to a hard disk - Input/output error

>Thanks to Simon, To: linux at lists.samBrett, Tomasz and others for replies.  
>Yes your script fix 
>worked well thanks. Now I've got the info I wonder what it all means!
>I wanted to find out the correct block size to put into the 'dd' command 
>... does anything stand out to you as block size?
>Anyway thanks very much for your help,

Since you are trying to create an ISO image file you might get more 
consistent results by using "readcd", which is specifically for reading CD 
reliably, instead of "dd".   After all, your attempting to read CDR, not 
pressed CD.  It's only for SCSI devices, but perhaps it will work under SCSI 
emulation.  I've had good results with it on a native SCSI CD drive (or you 
could use your burner, if it's SCSI, as a reader). 
>(in the mean time I have been checking cds given to me by using 'dd 
>if=/dev/cdrom | md5sum' and finding that supposedly exact copies give 
>different checksums .... could this be their M$o/s burner software 

The original CD you mentioned would be "bootable".  Do all copies boot - if 
not, then some may not have been made using the "CD Copy" mode of the burner 

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