Tuesday, December 16, 2008

A Date with Disaster

Last week I talked about being prepared for data disasters. Fate, it seems, is not without a twist of irony. Having returned from a short holiday, my camera's memory card was full of pictures and memories. They looked absolutely fine on the camera. Upon importing them into my computer, I was greeted by an error - "367 photos failed to import". Browsing the flash card directly showed a bunch of gibberish. Filenames were corrupted and directories were scrambled.

Digital storage media, be it a hard disk or a pen drive or a flash card, may suffer corruption. This is different than a physical failure, where the device stops responding entirely. Fortunately, it is easier to recover from corruption on digital media than in politics.

The first step would be to take your corrupted hard disk out of the computer and place it into an external USB casing, making it portable. Using a USB cable, connect your hard disk to a working computer. Do not attempt to read or write from the disk directly.

The second step is to use file recovery software. There are many available in the market for a high price, but none can beat PhotoRec in terms of success rate and price. PhotoRec uses what are called "file carving techniques" - to extract data block by block directly from the disk's sectors and piece it together. It can therefore look into disks which cannot be read by the system. The name is slightly misleading. PhotoRec was originally written for extracting image files, but works as well most types of files - documents, ZIP files, mailbox files and many more. PhotoRec is available at http://www.cgsecurity.org/wiki/PhotoRec.

Lastly, no PC troubleshooter should be without the Ultimate Boot CD (UBCD). As the name says, it is a collection of diagnostic and recovery tools, including PhotoRec. UBCD is available at http://www.ultimatebootcd.com/ and a Windows version at http://www.ubcd4win.com/

The price for all these fantastic tools? Free! And yes, I was able to recover 366 out of 367 lost photographs, thanks to PhotoRec. Read the Cyberwatch blog for my photo recovery adventure and a quick tutorial on using PhotoRec.

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