Disaster Recovery Software

 One option is the ubiquitous Windows Recycle Bin.  This little dandy has been around for a while.  In essence the Recycle Bin is sort of a state of deletion for a file that comes between deletion and removal.  When you usually delete a file in Windows Explorer, the file goes to the Recycle Bin unless you take steps to prevent it. 

The Recycle Bin can get full and start discarding older files.  You can control the size of the Recycle Bin, but you need to remember to clear it out every so often. It’s remarkable, sometimes, the amount of hard disk space being taken by computer users who have large amounts of space reserved for their Recycle Bin.  And, not all files necessarily go to the Recycle Bin.  If you happen to be working in the Window command line prompt (the old C: prompt) and you use the DEL or DELETE command, you may be surprised to find that the files deleted don’t get to take that side trip to the Recycle Bin; the command line bypasses the Recycle Bin for delete file operations.  When it comes to recovering files from the Recycle Bin, it is as simple as opening it in Windows, selecting the file that you want to recover, and selecting the Restore option from the right-click context menu.

Another option is to use one of the many commercially-available software programs that perform similar operations.  These programs typically allow you to access files that have been deleted and then to recover them.  Better programs will give you search options to locate the files that have been deleted.  Use care when purchasing one of the numerous programs from the Internet that provide this functionality.  Some of these programs have significant limitations on what they can restore and/or have limitations on the ability to locate files for restoration. 

In the worst case, they simply won’t work.  However, there are viable options on the Internet to be found as well.  In this, as in many cases, do your homework and check into reviews of the software by actual users before you plunk down your credit card and commit to the purchase of something that doesn’t meet your needs.  Remember, this software is going to be a part of your disaster recovery toolbox so make sure that it will do what you need.

So how do these programs actually work?  What necromancy is going on here that allows programs to bring your data files back from the dead?  It’s pretty simple, really.  In Microsoft Windows, for example, files are stored in chunks of your hard disk that are of a fixed size.  A big file will take several (or several hundred or more!) of these chunks while a small file may take only a single chunk.  These chunks are typically linked together in a chain, with one chunk pointing to another.  When you delete a file, Windows doesn’t erase the whole chain of chunks.  What it does is go to each chunk and mark it as being not in use. 

This tells Windows that the chunk can be re-used later when it is needed.  Files in the Windows Recycle Bin are marked in a special way so that Windows knows not to show them expect in the Recycle Bin window.  When you use a file recover program, these chunks are re-linked together and marked again as in use, thus recovering your file.

However, there are some limitations to what file recovery programs can do.  What if you delete a file at 9am and then realize that you want it back at 1pm that same day?  For a period of four hours, those chunks were marked as free for use by other files.  If, in that time, another file used some of the chunks, it is unlikely that a file recovery program of any kind can recover the whole file.  Some programs can partially recover the file and could, for example, rebuild a word processing document of a certain percentage of pages out of a whole file.  The point is that file recovery software provides a safety net of sorts, but it is not a foolproof tool and one that should certainly be used along with regular backups of critical files.