The sys admin's daily grind: ddrescue and DDRescue-GUI
Recovery Needed
Sometimes even sys admin Charly doesn't have a backup at hand; or, maybe it's ruined because the removed disk had corrupt data. Here, he offers some advice on how to handle the situation.
Krrr, krrr …! At least things are clear-cut when a hard disk gives up the ghost: You toss the offending disk, get a new one, and put the backup on it. However, those undead data media – that trick people into continuing working on them with no idea of the potential impact – are a real pain.
I recently determined that an SDHC card in my camera saves one out of 20 images (on average) as a colorful mess of pixels. I do know that memory cards give up the ghost sooner or later. However, I didn't realize that my camera could save to two cards simultaneously – a feature I stupidly didn't use. But, I'm all the wiser now.
What if really important data is stored on a haywire device that you just can't get rid of? This is where ddrescue
[1] comes in. The tool is already quite ancient, but its developers look after it untiringly and adapt it to new types of data media. (It should not be confused with the even older dd_rescue
.) Ddrescue is officially named GNU ddrescue; the packages on Debian and derivatives are therefore dubbed gddrescue
.
The tool is included with many popular distributions. The first two letters subtly indicate a relationship with dd
, and ddrescue
actually generates a data medium's or partition's image. Unlike dd
, however, it can't be stopped by read errors; instead, it stubbornly saves everything that it can get its teeth into.
Two-Speed Transmission
Administrators usually use ddrescue in two phases. The first phase involves creating an image with all the data that can be accurately read. In the following example, /dev/sdd1
is a partition with read errors on a USB flash drive:
sudo ddrescue -n /dev/sdd1 /home/charly/stick.img logfile.log
The second, more time-consuming phase involves using the tool to sort through the faulty blocks and save as much data from them as possible. The command is just the same as before, except you leave out the -n
parameter. In the wake of ddrescue, there is still an armada of other parameters that control the tool's behavior.
There is also a GUI [2] that you can use to make some quick, useful default settings. I installed it quickly on my test Ubuntu using these three steps:
sudo add-apt-repository ppa:hamishmb/myppa sudo apt-get update sudo apt-get install -fym ddrescue-gui
As Figure 1 shows, the interface is businesslike and functional. The GUI sets the important parameters, but not all of them by far. Although I hope no one will need to use ddrescue permanently, the GUI is nevertheless a real help.

Infos
- ddrescue: http://www.gnu.org/software/ddrescue/
- DDRescue-GUI: https://launchpad.net/ddrescue-gui
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you've found an article to be beneficial.
News
-
The GNU Project Celebrates Its 40th Birthday
September 27 marks the 40th anniversary of the GNU Project, and it was celebrated with a hacker meeting in Biel/Bienne, Switzerland.
-
Linux Kernel Reducing Long-Term Support
LTS support for the Linux kernel is about to undergo some serious changes that will have a considerable impact on the future.
-
Fedora 39 Beta Now Available for Testing
For fans and users of Fedora Linux, the first beta of release 39 is now available, which is a minor upgrade but does include GNOME 45.
-
Fedora Linux 40 to Drop X11 for KDE Plasma
When Fedora 40 arrives in 2024, there will be a few big changes coming, especially for the KDE Plasma option.
-
Real-Time Ubuntu Available in AWS Marketplace
Anyone looking for a Linux distribution for real-time processing could do a whole lot worse than Real-Time Ubuntu.
-
KSMBD Finally Reaches a Stable State
For those who've been looking forward to the first release of KSMBD, after two years it's no longer considered experimental.
-
Nitrux 3.0.0 Has Been Released
The latest version of Nitrux brings plenty of innovation and fresh apps to the table.
-
Linux From Scratch 12.0 Now Available
If you're looking to roll your own Linux distribution, the latest version of Linux From Scratch is now available with plenty of updates.
-
Linux Kernel 6.5 Has Been Released
The newest Linux kernel, version 6.5, now includes initial support for two very exciting features.
-
UbuntuDDE 23.04 Now Available
A new version of the UbuntuDDE remix has finally arrived with all the updates from the Deepin desktop and everything that comes with the Ubuntu 23.04 base.