Re: [Bug-ddrescue] Help

[Kristian Benoit]

Thanks, I just realized that I did not press on "reply all" in my first
reply and I think this discussion might be useful for others.

So basically, to test my computer, you suggest to copy data using ddrescue
from a working device (it could be a small USB key) into another device and
compare their binary content with diff?

Merci pour ton aide 🙂,
Kristian


On Nov 16, 2017 6:11 PM, "Adrien Cordonnier" <address@hidden>
wrote:

Hi Kristian,

>From your description, it appears that the disk is unresponsive on your
computer but not on your friend's computer. Normally ddrescue can stop
within one minute, even if trying to read a bad sector. If ddrescue cannot
stop, it means that the disk is not responding. As it is responding on your
friend's computer, I suspect that the problem is in the connection.

It has happened to me once with a defective USB controller and once with a
defective motherboard. With the defective USB controller, I tried to
recover the content with ddrescue thinking that the disk was failing. The
disk was further damaged before I understood the cause. It may not show
with other devices, for example it does not matter if a few bits are wrong
for a mouse. Now I always make sure to have reliable hardware for the
recovery. Then I investigate whether I continue to use the suspect
hardware, but only once the data is safe.

In the two previous cases, I detected the defect by comparing data taken
from a disk known to work and different connections (IDE/USB/SATA). Yet
with the defective USB controller, it also damaged this second disk.
Considering the price of the USB controller compared to the price of the
disks, I think I should have replaced it from the start. I would have saved
some money and a lot of time.

Cheers,

Adrien



2017-11-16 16:54 GMT+02:00 Kristian Benoit <address@hidden>:

> Why do you suspect defective hardware on my computer? I suspect that, if
> not told and the map is stopped in the first pass, ddrescue assume the map
> is complete, do a check of the saved data and switch to the second phase.
> At least, that is what it seemed.
>
> USB is normally working fine. The disks where also plugged through an
> extension (USB hub), another suspect from what I understand of your view,
> but if I plug other hardware on this hub/in this computer, they are working
> fine. What make you suspect defective hardware on my computer ?
>
> If they are defective, I would try to fix or at least, confirm it. How
> would you investigate failing hardware so I could confirm that supposition
> (without using my failing hard drive)?
>
> Kristian
>
> On Nov 14, 2017 4:56 PM, "Adrien Cordonnier" <address@hidden>
> wrote:
>
> Hi Kristian,
>
> You likely have defective hardware in your own computer (bus adapter or
> disk controller). I advice to complete the rescue with a reliable computer
> such as your friend computer, continuing with the map file from your
> friend's computer: if the adapter or controller is damage, the data
> recovered with your own computer may have been altered during copying.
> Don't forget to identify and change the defective part, it will damage your
> next disk.
>
> Good luck,
>
> Adrien
>
> 2017-11-14 19:53 GMT+02:00 Kristian Benoit <address@hidden>:
>
>> Hi,
>> I'm trying to use ddrescue, with some issue, I hope you can help me.
>>
>> So here's my process so far:
>> My USB hard drive (2 GB) was slow. So I thought of using badblock, after a
>> few hours it did not find anything bad, but was still at 0%, so I stopped
>> it and the drive was no longer mounting. So a friend of mine suggested to
>> use ddrescue. I went to his place and started ddrescue, after a few hours,
>> as we were reading it could restart where it was, I decided to do it from
>> home so I stopped it (Ctrl-C).
>>
>> Here's were it starts to go weird:
>>
>>    1. At home, I restarted with the same command (sudo ddrescue -f -n
>>
>>    /dev/sdb1 /dev/sdc1 dd_rescue.log). dd_rescue.log was the copied map
>>    from the previous run at my friends place. It was first checking
>> something
>>    (I dont remember what ?) then it reported being in second (pass/phase
>> ?)
>>    and  backward. Something's wrong I should stop it. So I then (Ctrl-C)
>> and
>>    nothing was happening, it was ignoring (I thought) my Ctrl-C so I
>> pulled
>>    the plug after a few minutes.
>>    2. I was waiting/searching for more help during a few days and the
>> other
>>
>>    day, I accidently try to mount the (backup) hard drive. It told that it
>>    failed to mount it, but did not say anything about trying to fix the
>>    partition, did it change the change anything to the rescued map ?
>>
>> Searching for help with the first topic was already hard and now I must
>> find some more info. Some help would be appreciated, thanks,
>> Kristian
>> _______________________________________________
>> Bug-ddrescue mailing list
>> address@hidden
>> https://lists.gnu.org/mailman/listinfo/bug-ddrescue
>>
>
>
>