<snip> All references to non FOSS software.

 

Greetings!

 

First, and most important, please allow me to complement you on one of the
best and most efficient recovery utilities I have found.

 

Allow me to suggest the following entries be included in future
documentation:

.         Within the "useful things you can do with ddrescue" part of the
documentation. . .
Ddrescue is excellent for ripping unprotected CD's and DVD's since it will
read every sector on the disk, whereas a straight "dd" bombs at the end if
the copy size is larger than one sector at a time.  (And a one-sector read
is slow as . . . .)

o   Example:  I have a newly received Ubuntu distribution disk that I
ordered, and I like to create image, (iso), files of these disks so that if
one is damaged or lost, I can recover from the image.  If I use "dd [infile]
[outfile] bs=(some multiple of 2048)" then - unless the disk is EXACTLY the
same multiple long - the last read fails with the potential for data being
missed.  If I use ddrescue, I can choose an efficient large chunk size for
the rip.  Once I reach the end of the disk, there's an EOM (end of media)
collision that causes ddrescue to back-off and make progressively smaller
reads until the last 2048 bytes is read - whereupon it ends.

o   Command used:  ddrescue [option: block size = 2048 bytes] [option:
blocks per initial chunk = 512] /dev/sr0 (or whatever) ./diskname.iso
./diskname.log - which assumes you're sitting with a terminal window in the
folder you want to write to.)  Note that I am not on my Linux box while I
write this, and I don't remember the exact option commands.

.         Within the "Rescue methods" of ddrescue. . . .
If you have a failed CD/DVD (I order and receive software and - more often
than you would think - one or more of the disks are defective), and if you
have access to multiple optical media drives, you have a better chance of
recovering the bad sectors since one drive may fail to read a particular
sector, but another drive might be able to squeeze the data out of it,
depending on the laser frequency and the sensitivity of the laser-sensor
that reads the reflected laser light.  This is especially useful if you only
have one copy of a disk, and it fails when being imaged.  This has worked
for me on many occasions where I have only one copy of a disk, it was
ordered to help repair a customer's system, and I don't have time to wait
for the replacement disks to arrive.

 

Again, let me thank you for an excellent utility and let me express my
gratitude on behalf of everyone who depends on ddrescue, but has not had the
time to write you personally to express their thanks.

 

Jim "JR" Harris 
Principal Engineer / Owner

Arrowhead Computer Consulting, LLC

 

Some see things as they are, and ask "Why?" 
I dream things that never were, and ask "Why Not".
Robert F. Kennedy 

 

"Impossible" is only found in the dictionary of a fool. 
Old Chinese Proverb 

 

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