Re: [Bug-ddrescue] GNU ddrescue HELP

[Florian Sedivy]

Hello Kevin!

You would NOT want to access an already damaged disk through the Finder, 
especially not while you are trying to get a consistent image of the drive. 
And you do realize that to "Initialize" or "Format" a disk means to erase its 
contents on purpose? That's why you don't see the partition any more. 

I am sorry, but from your first email I supposed you basically know what you 
are doing and just need some tips for optimization. Now I see that this might 
not be the case. 

So if the data is as important to you as you write, the only responsible advice 
I can give you is to leave it alone and hand it over to a professional. Give 
him also the partially recovered "Rescue.dmg" and a detailed record of what you 
did to the drive so far. This might help recovering some of your data, if you 
are lucky. 

Greetings, 
Florian

Am 11.10.2014 um 05:14 schrieb Kevin Doan:

> Hello Florian,
> 
> Thank you very much for your kind detailed reply. I think my external hard 
> disk has really faced its destiny.
> 
> I can’t access the hard disk anymore even from finder, I did some research 
> and I saw if I click on Initialize it actually formats the hard drive but 
> when I choose Ignore then pretty much nothing happens.
> 
> <PastedGraphic-1.png>
> 
> I have many years of data and would be really pity if nothing could be 
> recovered :-(. Is there any method to at least get to see the files from the 
> hard disk as I used to as it seems like the partition has completed 
> disappeared.
> 
> Once again thank you very much for your kind help.
> 
> Best regards,
> Kevin
> 
> On 3 Oct, 2014, at 21:27, Florian Sedivy <address@hidden> wrote:
> 
>> Hello Kevin!
>> 
>> Obviously you are doing this on a Mac. This and the actual command line you 
>> used would have been important details to share when asking for help. 
>> 
>> From what I can deduce, you are using -c 4096 (or probably -c 4Ki). In my 
>> testing values bigger than 256 sectors of 512 bytes did not improve speed 
>> any further. The only drawback of such a big value however are less frequent 
>> updates to ddrescue's UI, so while -c 256 would be the optimal value, yours 
>> probably did no harm. 
>> 
>> You can speed up the transfer a lot by using the raw character device 
>> instead of the block device. So in your case that would be /dev/rdisk3s3 
>> instead of /dev/disk3s3 IF the device did not change - always check the 
>> device name before you start ddrescue! Still you will need A LOT of patience 
>> if the drive has real problems and it certainly looks like it has. Let 
>> ddrescue do it's thing. 
>> 
>> There is no use in trying to write a partially rescued image to another 
>> partition. Even the last rescued byte could make all the difference to the 
>> validity of the enclosed filesystem. So just wait until you think you have 
>> everything the damaged drive is ever going to give you, before proceeding to 
>> the next step.
>> 
>> I seriously hope /Users/kevin/Desktop/MPA/recovery.log wasn't the original 
>> log file you used for the recovery? If it was, then you destroyed it by 
>> using it for restoring the image and will have to create a new one. You 
>> could either start over from zero or find a good backup of your log file 
>> (Time Machine?) or create a new log file from Rescue.dmg with ddrescue's 
>> Generate-Mode. Here I'd like to cite the help-screen: Do not use options 
>> '-F' or '-G' without reading the manual first!
>> 
>> By the way, you can mount .dmg images directly to check for your results, 
>> without having to restore it to a partition first. Most file system repair 
>> tools will also happily accept an image file. Just make sure you prevent 
>> writing to your original dmg so you don't compromise the raw rescue result! 
>> You can work on a copy, write-protect the original (obviously not while 
>> ddrescue is running), mount with shadow option, use some tool like Disk 
>> Arbitrator to prevent mounting read-write, or whatever you can think of, but 
>> let NO other tool except ddrescue write to your image before you have your 
>> data safe AND know exactly what you are doing. To be clear, that also means 
>> DON'T just double-click Rescue.dmg without having protected it first!
>> 
>> Good Luck, 
>> Florian
>> 
>> Am 02.10.2014 um 23:54 schrieb Kevin Doan:
>> 
>>> Dear Sir or Madam,
>>> 
>>> After many research I found your great tool on your site and spend =
>>> several days on trying to recover my damaged external Western Digital =
>>> hard drive. That being said, it seems like it is taking eternity for it =
>>> complete therefore I hope if you could help me. I have stopped the =
>>> process and restarted the PC but speed is still extremely slow.
>>> 
>>> GNU ddrescue 1.18.1
>>> About to copy an unknown number of bytes from /dev/disk3s3 to =
>>> /Users/kevin/Desktop/Rescue.dmg
>>>   Starting positions: infile =3D 0 B,  outfile =3D 0 B
>>>   Copy block size: 4096 sectors       Initial skip size: 128 sectors
>>> Sector size: 512 Bytes
>>> 
>>> Press Ctrl-C to interrupt
>>> Initial status (read from logfile)
>>> rescued:     8716 MB,  errsize:   6676 MB,  errors:    2056
>>> 
>>> Current status
>>> rescued:     9177 MB,  errsize:   7092 MB,  current rate:        0 B/s
>>>  ipos:    77938 MB,   errors:    2142,    average rate:     118 kB/s
>>>  opos:    77938 MB, run time:    1.07 h,  successful read:      38 s =
>>> ago
>>> Copying non-tried blocks... Pass 1 (forwards)
>>> 
>>> 
>>> Even with the incomplete the Rescue.dmg file I tried to use the below =
>>> command to recover the files:
>>> 
>>> kevin$ sudo /opt/local/bin/ddrescue --force -v -c 4096 =
>>> /Users/kevin/Desktop/Rescue.dmg /dev/rdisk4s2 =
>>> /Users/kevin/Desktop/MPA/recovery.log
>>> 
>>> But without any luck. Any help you could provide is greatly appreciated.
>>> 
>>> Thank you and best regards,
>>> Kevin
>>> 
>>> _______________________________________________
>>> Bug-ddrescue mailing list
>>> address@hidden
>>> https://lists.gnu.org/mailman/listinfo/bug-ddrescue
>> 
>