Using CentOS 7 To Attempt Recovery Of Failed Disk
I have a disk that is flagging errors, attempting to rescue the data.
I tried dd first – if gets about 117G of 320G disk and stops incrementing the save image any more.
Now I’m trying ddrescue and it also stops about the same point
Thoughts on how to continue past that point ?
Thanks,
Jerry
9 thoughts on - Using CentOS 7 To Attempt Recovery Of Failed Disk
did you try
dd conv=noerror …
this flag makes dd not stop on input error. Whatever is irrecoverable is irrecoverable, but this way you will get stuff beyond failure point.
Valeri
Also, does ddrescue “stop” (as in quit) or is it just stuck there spending a lot of time trying to read one or more bad spots? it is intended to keep trying until it gets something, or gives up and skips to the next track/sector/whatever. If you let it go for a long time (overnight???) does it proceed ?
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Hello
I did try the “dd conv=noerror …”
The ddrescue – doesnt stop – it just doesnt “continue” past a certain point. Somewhere around the 117G mark – it just doesnt go past that .
(same with dd, gets to 117G and just doesnt continue. I have let the dd run all night – did not go past the 117G.
Thanks for any suggestions.
Jerry
Well, I’m not a noted expert on ddrescue, but my limited experience tells me that when it hits bad spots (or a big cluster of them) it can go very slowly as it tries multiple times to read each sector (or track, I’m not sure which, in this case). It keeps a list of bad spots and goes back at the end to try again to read something from them. Of course, if you’ve had, eg. a head crash, there’s probably nothing there to read.
CentOS mailing list CentOS@CentOS.org https://lists.CentOS.org/mailman/listinfo/CentOS
I will suggest using dmesg -w to monitor during dd the sector numbers that fail in order to skip them.
Also, perhaps the timeout of each read error is killing you (default 30
seconds) and you may have thousands.
CentOS mailing list CentOS@CentOS.org https://lists.CentOS.org/mailman/listinfo/CentOS
You can interrupt ddrescue and then resume with “-R” (–reverse) option. That will make it start from the end of the device and read backward toward the trouble area.
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Thanks everyone for the suggestions. I finally got a completion with this command:
dd conv=noerror,sync iflag=direct bs@96 if=/dev/sdb of=disk.img
Copying it now to see if it worked.
Jerry
“It is alive”! Fantastic.
So I got a new SSD (500G) to replace the OLD rotating disk (320G) and played with trying to copy off the data for days… Finally got that with everyones help. Today I copied the data to the new 500G disk and it BOOTED and running.
Monday is way better than Friday was!
Thanks and have a great day.
Jerry