Rather than trying your as* off to recover data afterward, it’s always best to take some precautions (no disrespect intended :D). This is one of the reasons why most people (including me) like to backup their data to optical discs such as CD/DVD or Blu-Ray discs rather than using Hard Disk Drives as optical discs can keep your data safe for years.
For instance, because the HDD is a mechanical device rather than a electronic one it has somewhat a shorter life-cycle (you know the poor bugger is always spinning, parts easily wear out etc). And also the margin for error is very little (sudden drops can be fatal) too. But that’s not to say that the optical discs are perfect since they too have their own vulnerabilities.
For instance unlike with HDDs… they’re more prone to scratches, accidental drops etc and if you use a low quality product then within a short period (say 2-3 years, if you’re lucky) you could end-up with a discs that’s “transparent (unreadable), if you know what I mean.
So, most of the time if a sector becomes unreadable due to those types of error there’s very little we can do where with HDDs, if the issue is with the motor then experts may have a shot at repairing them. Anyhow, there’s an awesome utility that I came across few years ago that gives a mechanism to easily recover data from damaged optical discs (it works extremely well, but no guarantee though).
It’s called DvdDisaster. Now before you get confused, this is not a CD/DVD data recover utility that you can use after the disc damage occurs, it’s rather an application that you should run while the optical disc is fully read-able!.
What Dvdisaster basically does is, it actually first scans your fully readable disc and creates a database (takes about 15% of the size of the actual disc) that it’ll use as a “guideline” in the future attempts of data recovery on that disc.
If you want a bit technical info, then what Dvdisaster creates is acutally a checksum file of the optical disc’s content.
*. Dvdistater can create a error-recovery file out directly from your optical drive or if you already have an ISO image file then you can load it to the program and create the recovery content from that as well.
*. You can access few additional settings such as: Drive read speed, accessing methods, change the reading sector manually, wait seconds for optical drive to spin-up, change memory cache and other few advanced settings from the preferences window.
*. Supports CD/DVD and Blu-Ray mediums. Read this official supported media page for more.
*. Cross-platform utility thus you can use it in MS Windows and Mac OSX apart from GNU/Linux.
You can install Dvdisaster in Ubuntu 11.04 Natty Narwhal, 11.10 Oneiric Ocelot, 12.04 Precise Pangolin, 10.10 and 10.04 (may work in the older versions too) by using the below command in your Terminal window.
sudo apt-get install dvdisaster
How can I use it?
I won’t be going into all the details because you can get all the instructions from this official Dvdisaster help page (extremely easy to follow). But for a basic data backup and recovery afterward, this is what you gotta do.
*. I’m assuming that you have a perfectly read-able optical disc (they say that it’s okay even if it has few errors). Then put it into the disc drive and load the newly installed Dvdisaster utility.
1. We have to create an ISO image of the disc. And then Dvdisaster will use that ISO image file to create the recovery data. So make sure to have a free space according to your medium.
2. Now open Dvdisaster and from its main window, choose your optical disc drive and hit the “Scan” button to your upper right corner as with the below screenshot (you can change the ISO and recovery data path using this window too).
3. This should start the process and you should see a graph and a circle (representing sectors) showing the progress (shown in Step 2). As long as the circle fills up with “Green”, is good but if there are a lot of “Red” sectors… it could mean trouble.
4. Now for this example I used a burned CD of Ubuntu 11.04 (about 695MB) and at the end it did gave me a “warning” saying that two sectors to the end are missing (yikes!). But the app itself suggested that this is pretty normal if you burn the CD in TAO mode (default mode in may burning apps).
5. Now click the “OK” button and it’ll save a complete image of the disc in the ISO format.
Now, from the main window, again just below the “Read” button to the upper right corner, this time click on the “Create” button (with the Ying-Yang sign :D) to create the error recovery file (uses the “.ecc” format) and this should open a progress bar window as shown below.
That’s it!. Now go to your “Home” folder and look for a file with the extension of “.ecc” and in my case the source image file is about 695 MB and the error recovery file is about 99MB which is like 15% of actual content. You can delete the ISO file but do not delete the “.ecc” file.
Now make sure to keep/store this “.ecc” file in a very safe manner because if you wanted to recover the data in that disc (say due to a bad scratch or comprehensive sector damages=transparent discs), then Dvdisaster will ask for this specific image.
How can I recover data afterwards?
Simple. Just put your somewhat troublesome disc drive and load Dvdisaster.
Now also make sure to enter the path of the error correction file (ecc) from the upper section. Now from the main window choose “Scan” button, Dvdisaster will start scanning for any damages and if found, it will recover your data and put it in an ISO disc image.
But remember, there’s no guarantee that you’ll be able to recover all the data, all the time… but if you’re willing to accept the fact that you’ll need additional backup storage (about 15% per medium for the error correction file), then Dvdisaster can come in extremely handy.