Simply put, anytime that your files and data aren’t accessible you will need to perform data recovery to get them back. That sounds simple enough; however, the recovery process is not always that simple and may, in fact, be a rather complicated ordeal at times.

Types of hard drive failure

To better understand how files are recovered, it might be a good idea to find out why they got lost in the first place. While there are many different reasons a file could go missing, there are only two causes for loss: logical failure and physical failure.

While you may have heard those terms applied to hard drive failure, understand that other forms of media fail. USB memory sticks and digital camera media cards also fail. Even though floppy disks aren’t as prevalent as they once were, floppy drive recovery is still done occasionally.

Logical Drive Failure and Recovery

We’ll start with logical failure because it is the easiest to understand and often the easiest to recover from. This type of failure stems from a failure in the logic, or coding of the drive media. It would be safe to say that almost every computer user has experienced a logical failure; and if they haven’t yet, they certainly will at some point.

Accidental or Intentional Deletion

File deletion, both accidental and intentional, is a form of logical failure. Hopefully, the files are still resident in the operating system’s Recycle Bin or Trash Bin. Recovering the files would simply being a matter of restoring them to their previous location. Unfortunately, it’s rarely that easy.

On the plus side, files are not actually deleted until they are overwritten by another file. With today’s large hard drives, that could take a while. What happens is that the identifying markers or pointers are removed from the files, breaking their association with any programs used to access them. To recover them, they must be found and the association restored.

Data recovery software does exactly that. It finds the missing files, restores the broken association and makes the files accessible again.

Any form of digital media can be recovered this way. However, some logical failures are more complex than accidental deletion.

Operating Failures and File Corruption

These types of logical failure are a bit more complex and require a more intensive recovery process. However, they still may be recovered using a data recovery software program.

These logical failures are caused by several conditions:

• Malware and virus attacks that corrupt system file and data file structure • Improper shutdown of the computer by the user • Improper shutdown of the computer as a result of power failure • Removal of storage media while it is still being written to

In most cases, these issues are resolved using a recovery program; although in the first one, OS corruption, an emergency boot disk may be needed if the computer will not boot up into the operating system.

While data recovery by software is effective, although time consuming, there is one caveat that must be considered. It is prudent to have installed the software before data loss occurs. If the software is installed after the data is lost, the act of installation may overwrite the very files that are to be recovered. If this is the case, using the emergency boot disk is preferred and the recovered files should be written to a secondary media location, such as an external disk or flash drive.

Physical Failure and Recovery

Now it’s time to turn our attention to a much more formidable foe: physical failure. Again, this type of failure can occur to any digital storage media, not just hard drives. However, hard drive physical failure is common and it can be difficult to recover the files.

In a physical failure, data loss is caused by actual damage to the hard drive itself, either mechanically or electrically. Some of the causes for physical failure are:

• Normal wear and tear on the read/write heads of the recording component. If the heads stop working, data cannot be retrieved. A grinding sound emanating from the computer is usually a warning sign of this type of failure. Turn off the computer immediately to prevent further damage.

• Damage to recording media caused by worn or damaged read/write heads. The recording surface can be damage by contact with the head.

• Electrical or electronic damage, often caused by voltage spike or surges. Lightning during a storm can send surges through the power lines, damaging equipment.

• Physical abuse of the drive or computer damages the drive media. For example, excessive heat exposure, such as when a laptop is left on the back ledge of a car and exposed to the sun’s radiation and heat, will damage delicate drive media.

• Contact with water and other liquids can damage delicate drive components. While often associated with rain storms and flooding, don’t forget that a USB stick or digital camera media card may need special attention if run through a washing machine cycle!

Physical drive failure recovery is more involved

Because of the nature of physical damaged components, a data recovery software is rarely, if ever, successful. If is it used, it must be deployed as part of a process that includes drive repair. And while logical data recovery can usually be done by the computer user or a computer savvy friend, a hard drive recovery service is needed for physical drive failure recovery.

Any person with a few tools and a little patience can replace almost any component on a computer, even the hard drive. However, hard drive repair is another thing altogether. For one thing, if the computer is still under warranty, any unauthorized person opening the hard drive case will void that warranty.

Secondly, hard drive repair is not something that can be done successfully on the kitchen table, in the garage, or in any normal environment. When a drive is exposed to normal environmental conditions, airborne dust and debris will contaminate the delicate surface of the recording media, preventing a successful recovery.