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When Good Disks Go Bad - Part 1

by Alan German

You insert your external drive. Windows coughs and splutters, and the dreaded - your disk is not accessible - message box is displayed! This happened recently to a friend who is an avid nature photographer. On her return from Uganda she plugged in a 32 GB SDcard, nominally containing over 1000 photographs, and found that she was unable to access any of the images.



So, now what? Well one option, offered by the service department of a big-box computer store was to hand over the memory card – and $300 – and see if the files could be recovered. Another option is the do-it-yourself solution. Find some disk recovery software and use it to try to recover the disk’s contents.

Now, while I am a huge fan of free software, the bad news is that I am not aware of any such products that will recover data from large-capacity disk drives. Sure, many commercial packages offer trial versions to provide recovery capability, but these always seem to be limited to something like the first gigabyte of recovered files. Addressing the needs of larger data recovery efforts requires use of the full-blown package.

So, it may well be possible to use a trial version of some data recovery software to check out the possibility of accessing a corrupt drive, but it will almost certainly be necessary to purchase the full commercial package in order to recover all the data from the disk.

Fortuitously, for my friend, around the time of her issue with the SDcard that had gone bad, I had been approached by MiniTool to review their Power Data Recovery software. Initially, I had declined to undertake the review since I couldn’t see how to meaningfully do so without having a corrupted drive to work on. Clearly, my friend’s SDcard provided the perfect candidate for a real-world test of the program. So, armed with a licensed copy of MiniTool’s Power Data Recovery software, I was ready for the challenge.

Downloading and installing the software was simple and straightforward. The program’s main screen provides access to a number of modules. My first choice was the sub-program named Digital Media Recovery since this seemed to be the most appropriate potential fix for the SDcard in question.



Starting the recovery process brought up a dialogue box indicating the progress of a scan of the SDcard and, most heartening, an indication of the number of files that had been recovered. Another useful feature of the display was an indication of the likely time remaining to complete the scan. Since this was of the order of 25 minutes, it was obviously time to make a pot of coffee!



Eventually, without me doing anything more than enjoying my coffee, the display changed to advise me that 1030 files had been recovered. The 24.91 GB of data comprised RAW digital image files which were contained in a number of folders and sub-folders. So, it appeared that both the individual data files, and the file structure on the SDcard, had been recovered. I was now able to select all the recovered files and folders and save them permanently to the hard disk on my computer. Success!

Flash Drive Recovery

The second test that I performed was to check the Undelete Recovery module. In this case, I deleted all the files from a USB flash drive. I copied a number of files – a selection of jpg, exe, docx, txt and pdf files – to a folder on my hard drive, and then copied the files from this folder onto the USB drive. Then, I deleted the files from the flash drive so that it was nominally blank. Running the Undelete Recovery process from the Power Data Recovery software very quickly recovered the files on the USB drive.

Most of the files were restored to their original state on the USB drive. A couple of files had the first characters of their file names replaced with the underscore character. This was not totally unexpected since this character substitution is part of the process by which Windows marks files as being deleted. Restoring the original file names was simply a matter of renaming the restored files (e.g. _SC_0184.JPG was renamed to DSC_0184.JPG.)

Once this process was complete, a bit-for-bit file comparison, between the restored files on the USB drive and the original files in the folder on the hard disk, confirmed that the recovery process had been 100% successful. Another triumph for Power Data Recovery!

CD Recovery

The software developers indicate that the CD/DVD Recovery module “is designed specifically to recover lost and deleted files from damaged, scratched or defective CD and DVD disks”. I happened to have a CD that was refusing to open one of several hundred digital photos that were backed up on the disk, and so I opted to try to recover this specific file. The CD/DVD Recovery module’s operation was very similar to that of the previously-used Undelete Recovery module. I chose to conduct a Full Scan of the 698 MB CD. This took about five minutes and identified a number of files and folders. I selected the “corrupted” image file, which displayed correctly in the preview window, and saved it to Drive D: (the data partition on my hard disk).

The only real issue was that, after having saved the file, I couldn’t immediately locate it on the hard drive. It wasn’t saved to the root of the disk, rather it was stored as D:\ISO9660 & Joliet\$Root1\MON_001\001.JPG which was clearly a function of the original file system on the CD-ROM. However, once I realized that the file had been saved to a folder, it was simple matter to initiate a bit-for-bit comparison between the recovered image and a copy of the same file from a second backup on an external hard disk. The recovered file proved to be identical to the backup showing that Power Data Recovery’s third module was completely successful.

It turns out that I didn’t actually need to scan the CD, I could also have used the Open control button. For my test CD, this listed a number of tracks and the available files and folders on these tracks. Once again, the file I wanted to recover was listed, displayed in the preview window, and could be copied from the CD to my hard drive.

The CD/DVD Recovery module includes support for ISO9660, Joliet, and UDF formats, RAW files, and can process multi-session disks. This can lead to a fairly complex directory listing where, for example, my disk contained listings for the same files and folders in different sections (e.g. ISO9660 & Joliet ) or tracks (Track01, Track02, etc.). The good news I that it didn’t seem to matter which listed file I chose to recover.

The other two modules in Power Data Recovery are Lost Partition Recovery and Damaged Partition Recovery. Each of these modules is applicable to the partition structure of a hard drive. Using these modules is a little trickier than those for flash drives and CD-ROM’s so we will leave this discussion for Part 2.

Bottom Line:

Power Data Recovery (US $89.00)
MiniTool Solution Ltd.
Vancouver, British Columbia

Originally published: October, 2017

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