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OK, so my hard disk crashed the other day and I sent the entire notebook for servicing; now I have a brand new hard disk installed in it and the damaged one out in the open. I've installed Ubuntu and ddrescue with the intention of recovering all data from the C drive (200GB); so far it's been about 2 hours and I think it's going to be a very long time.

I ran the following line:

sudo dd_rescue /dev/sdb2 /mnt/sda4/backup.img

Things started looking good; it expected to retrieve 195354624kB from /dev/sdb2 and started copying stuff; however it's copying in chunks of 2119808kB with avg.rate of just above 400kB/s and an ETA of almost 130:00:00. I have to wait 5 days just to get all my data out?!

This webpage says that he took just 12+h to do 1TB, but given that my hard disk is damaged I should expect the time taken to be longer. Should I be optimistic and pray that it'd take less than 5 days? Currently the state of the hard disk is so bad that I can't view any of the files in Windows, the C drive says it's corrupted and unreadable, and the D drive hangs up the system when navigating through the files, and eventually disconnects each and every single time.

Is there any way to expedite ddrescue (while preserving as much data as possible), or am I doing something wrong?

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If you use ddrescue command from gddrescue package (it's not clear), then to speed up the process (and ensure your drive doesn't die too quickly!) you can use a log file:

sudo ddrescue /dev/sdb2 /mnt/sda4/backup.img logfile

After a couple of ours (or a day) of copying, you can stop ddrescue, let your drive rest (or put it in a colder room or storage), and when it's cooled down you can resume the process where it left off using the same command as above. Since the hard-drive will have time to breath, it will improve operational performance and might speed up the process. It is recommended to do that if the drive is dying.

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What is the file system of the hard disk where you save the rescue image and the logfile? I just made the experience of rescuing a 500GB internal hard drive (connected via SATA) on a Laptop running Linux Mint from a USB Stick, saving the rescue image and logfile on an exFat formatted USB hard drive.

It starting rather slowly (1-2MB/sec) but after around 250GB it was only crawling at <100KB/sec. It seemed to become slower the larger the rescue image file was growing.

Then I moved the rescue image and logfile to another temporary place, re-formatted the USB hard drive with the ext4 file system, moved the files back on it and resumed the ddrescue process - and now it runs with 1-20MB/sec again (fluctuating but around 7MB/sec on average)!

Seems like exFat does not play very well with very large files (several hundred gigabytes), so you might want to give ext4 a shot.

  • I've done the same for the recover target drive, but there's no speed improvement though, still ~60 KB/sec average rate. This means that it will take ages for the entire 1 TB drive ! The source drive is an external USB as well, NTFS formatted. – qdev Nov 14 '17 at 10:12

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