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Re: [Bug-ddrescue] Rescueing CDs burned with Track-At-Once

From: Antonio Diaz Diaz
Subject: Re: [Bug-ddrescue] Rescueing CDs burned with Track-At-Once
Date: Sun, 31 Aug 2014 20:28:00 +0200
User-agent: Mozilla/5.0 (X11; U; Linux i586; en-US; rv:1.7.11) Gecko/20050905

Hello John,

John Bokma wrote:
rescued:   667650 kB,  errsize:    4096 B,  current rate:        0 B/s
   ipos:   667652 kB,   errors:       1,    average rate:     565 kB/s
   opos:   667652 kB, run time:    1.88 m,  successful read:      52 s ago

Based on what I've read those are most likely 2 blocks created by
Track-At-Once: "two unreadable run-out blocks at the end of the track."

I think so.

Based on the above I calculate the size of the ISO image as: 32581 x
2048 = 667342848

The rescued image, however, is 667650048 bytes; 307200 bytes larger, or
150 blocks. Is this also a side effect of Track At Once?

Should I use the --size option (on both) to just grab the blocks as
reported by isoinfo?

I am no CD expert, but I remember to have read about some "150 lead-in sectors". If I were to store the iso images, I would store them complete just in case I cut the wrong 150 sectors out of them.

So dd and ddrescue give me an identical iso. The big question is, am I
at risk at losing data by specifying the size?

If the excess sectors are at the beginning, then probably yes.

Hope this helps.


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