How to recover data from Ext4 partitions?

Question

I've removed an old HDD from a computer and to install in another computer to use for data storage (personal files, specifically tv series episodes, not system files) and the file system that I've used was the Ext4, then, for some reason I decided to install another operating system in this HDD, I used the same file system for this OS (Ext4). But then I realized that this HDD, had a lot of tv series episodes that I forgot to burn into DVDs.

Now I'd like to recovery this old data. There is any software with GUI and if possible native, available to Ubuntu, to perform this task?

This is the output of sudo fdisk -l for that disk:

Disk /dev/sdb: 20.0 GB, 20019314176 bytes
255 heads, 63 sectors/track, 2433 cylinders, total 39100223 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x21033f16

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *          63    36132875    18066406+  83  Linux
/dev/sdb2        36134910    39098367     1481729    5  Extended
/dev/sdb5        36134912    39098367     1481728   82  Linux swap / Solaris

Answer 1

You had one system that contained a number of video files, then a new OS installation was performed.

If the new system was installed without reformatting, then the files may just be there, not needing recovery at all. (Check what folders are in /home; perhaps an old home directory from a previous installation is in there, next to your own home directory in the new installation.)

However, if the partitions containing the video files were removed or reformatted, and then data was written on the disk where they existed, it's highly probable the new data (from the newly installed operating system) irreversibly overwrote large parts of the video files. It's likely some parts of all of them were overwritten. This is hard to recover, it could take hours, days, weeks, or you might not succeed, and it would involve trying to repair damaged video files, since it's unlikely you'd be able to recover the files intact.

Unless the TV episodes you lost are rare and cannot be obtained again, it's not worth it to attempt recovery. What you'll likely get from recovery after the drive was formatted and another OS installed is, at best, highly corrupted files. While better outcomes are possible, probably most of the files would cut out and stop playing altogether, somewhere in the middle. It would be one thing if you had just accidentally formatted it, but once a overwriting has happened, data recovery is only worthwhile in cases where valuable, difficult-to-reconstruct data are lost.

It's a hassle to get the files again, and takes time, but so does data recovery, and data recovery will likely take more of your personal time and effort (while preventing that computer, or at least that hard drive, from being put to productive use).

Usually, I only recommend attempting data recovery if the likelihood the data has been overwritten is very low (not the case here), if the value of the lost data is very high (probably not the case), or if the data has intangible value that's hard to quantify but you are very attached to it (e.g., your own creative/artistic works regardless of whether or not they are monetizable; the only copies of pictures of your children or from a vacation with a now-deceased relative).

Still, if you want to try, there's a slight possibility you may recover significant data. It's possible that, by chance, the files were mostly located somewhere on the disk that was not overwritten by the new OS installation.

If you want to attempt recovery, first take a look at this page:

• Data Recovery (Ubuntu wiki)

You would image the drive, then perform analysis on the image to recover files from it. Photorec (it's not just for pictures) might be a good analysis tool to start with.

Also I recommend taking a look at this question:

• Is there any recovery software available for ext4?

Some of these other questions may also be of help.