Recover Data From a dead hard drive using ddrescue

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http://www.debianadmin.com/recover-data-from-a-dead-hard-drive-using-ddrescue.html

October 24, 2006 by Admin

Like dd, dd_rescue does copy data from one file or block device to another.dd_rescue is a tool to help you to save data from crashed partition. It tries to read and if it fails, it will go on with the next sectors where tools like dd will fail. If the copying process is interrupted by the user it is possible to continue at any position later. It can copy backwards.

[…] the whole article ignored because the author didn't even know that 'dd_rescue' and 'ddrescue' are different programs.

Moreover, jack Said on February 28th, 2007:

I think /dev/sda1 and /dev/sda2 are two partitions of the same hard disk. If you want to save a backup of the crashed sda1, you shouldn't place it onto the same physical disk.
/dev/sda2 is a device file, so the "/dev/sda2/backup.img" reference is invalid. You should mount the partition first, and then - if it has a writeable filesystem on it - you can create the backup file (the next example assumes that neither sda1 nor sda2 is mounted):
```
# mkdir /root/rescue
# mount /dev/sda2 /root/rescue
# dd_rescue /dev/sda1 /root/rescue/backup.img
```
I think when you try to mount a regular file as a partition you can only do it through a kernel loop device. It goes like this:
```
# mount -o loop /root/rescue/backup.img
```

Recover Data From a dead hard drive using ddrescue

Actually, there are two programs with similar names, 'dd_rescue' and 'ddrescue' (my preference)……The difference is 'ddrescue' is also known as gnu ddrescue, which can automate the whole process by specifying the log file option, and can resume where it left off if interrupted…….dd_rescue requires a separate wrapper script to automate it…

So you should make sure to use the correct name throughout the entire article, and not interchange dd_rescue with ddrescue….

documented on: November 4th, 2006, thegeekster

Recover Data From a dead hard drive using ddrescue

The big difference is that ddrescue can keep track of the bad sectors, and go back and try to do a slow read of that data. dd_rescue will slow down and read more carefully, yeah, but ddrescue is more thorough. Personal experience tells me that dd_rescue is ok for slightly wonky drives/removable media, but ddrescue is better for the slowly-dying-hard-drive variety of problem.

documented on: 10/25/06, regeya

Recover Data From a dead hard drive using ddrescue

The program described in this article is Garloff's original dd_rescue.

The program which I very much prefer is Diaz's newer GNU ddrescue.

Both are mature, well-respected tools. However, Diaz's ddrescue maintains a logfile so that it always knows what has been recovered, and what has not. So if you stop it (or your computer crashes) in the middle of a recovery operation, you can just run it again and it'll pick up where it left off.

Also, you can try again with different options (e.g., after disabling readahead or dma on the drive, or reading smaller chunks), or you can retry while reading from a raw device bound to the /dev/hdx instead of to the drive itself, to read individual sectors. It just works: if you put the drive in the freezer overnight, then hook it up and re-run GNU ddrescue with "-r 1" (retry bad sectors 1 time), it'll only try to read the unrecovered sectors, and won't waste time re-reading the parts that have already been recovered.

What's more, the logfile is plain ASCII and well-documented, so it serves as a record that you can use for other purposes. E.g., I've written a Perl script which reads the ddrescue logfile and spits out a Windows .bat file of 'nfi' commands, to determine which files on an NTFS file system are damaged.

documented on: February 3rd, 2007, Dave Burton

Recover Data From a dead hard drive using ddrescue

http://digg.com/linux_unix/How_To_Recover_Data_From_a_dead_hard_drive_using_ddrescue

Yet another disk recovery blog that fails to point out some very important information. While the rest of the blog is quite helpful, hard drive failures can occur for many varied reasons. Just listening to the drive will often tell you.

Does it spin up? No - it's beyond mere mortals.

Does it make a clicking noise? Yes - ddrescue as in the blog will probably help.

No clicking and it might just be a partial electronics failure. In such cases, hdparam will allow you to turn off some advanced drive features that will get around the part of the electronic component that has failed.

I've had 100% recovery of a few failed drives simply by turning off DMA access. (hdparam -d 0 /dev/hda) Other hdparam options can also help. Man hdparam for more information! Note however, that hdparam is most useful on IDE PATA devices. YMMV for SATA. For USB & SCSI, hdparam is next to useless.

documented on: 10/25/06, digg0t