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

[Antonio Diaz Diaz]

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.

Antonio.