Re: [Bug-ddrescue] Reverse not working on OS X

[Florian Sedivy]

Hallo Perttu!

It seems to me that ddrescue doesn't know the size of your disk yet and tries 
backward from 9223 Petabytes 1 sector at a time. "-i" does not help, because in 
a reverse run it specifies the end of operation. You COULD solve this by 
producing an approximate log file and option "-C" (complete only). 

BUT the better way in my opinion would be a normal run forward with "-i" set to 
a position after the bad beginning. This will be much faster than reverse mode, 
which ignores copy block size and goes strictly sector by sector (as far as I 
know). 

On OS X use the raw device (rdisk) and "-c 256" or more for better read 
performance. 

Greetings, Florian 

Am 29.12.2013 um 01:21 schrieb Perttu Aaltonen <address@hidden>:

> Hi,
> 
> I use ddrescue for every defective disk, great piece of software! I mainly 
> use ddrescue on OS X. Lately I've been trying to use the reverse-option for 
> disks that have most of their bad sectors in the beginning. For some reason 
> this isn't working. The position for rescue isn't right and nothing gets 
> transferred. For example, on a 320 GB disk I tried this the epos & opos are 
> shown as "9223 PB", even if I use the "-i" option to tell to start from a 
> certain position. The "time since last succesful read" only gets longer and 
> nothing transfers. I'm testing on OS X 10.7.5, ddrescue 1.17 installed from 
> MacPorts.
> 
> Br,
> Perttu
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