Re: [Bug-ddrescue] ddrescue errors: maybe yes, maybe no

[Antonio Diaz Diaz]

Hello Kevin.

Kevin Hubbard wrote:
> I have used PayPal to send "ANTONIO" $15 EUR = $20 USD.Confirmation Number 
> 7WL22909N9065834D on 2014-02-11 17:00 EST

Thank you very much. :-)

I am not a user of Mac, so I can only give limited answers.


> My objective is to identify the failing hardware sectors and thentry to have 
> Mac OS X reassign alternates.

If you use a logfile, the exact position of the failing hardware sectors 
is recorded in it.


> 1) What is the correct Sector (-b hardware block) size for AdvancedFunction 
> (AF) HDD in the Mac OS X environment - 512 or 4096 ? I didnotice that ddrescue 
> only accepts -b as 512 or some multiple of 512.

Ddrescue accepts almost any value as sector size, but of course only the 
right value (or a multiple) works (at least in direct access mode). 
(Unless your drive is simulating a 512 byte sector from a real sector 
size of 4096).


> 2) Why does changing the -b and -c values affect whether or not ddrescue 
> encounters errors ?

For -b see above. A large value of -c may produce a large error around a 
bad sector, but the good sectors should be read succesfully during the 
trimming phase.


> 3) Why does each output log start with 
> "About to copy 9223 PBytes from /dev/rdisk5s2 ..."
> when the partition/volume is 1.5 TB ?

Because ddrescue can't determine the size of some devices on some 
systems. An explicit --size option is needed in your case.


> 4) What does the ? in progress size value in the log always somegigantic 
> number, such as 0x7FFFFFE89F8FFFFF ? Does it have meaning ?
> Since 0x7FFFFFE89F8FFFFF = 9223371936452570000 then perhaps thisaccounts for 
> the 9223 PBytes message ...

Exactly.


Best regards,
Antonio.