(This article is about the different classes of data loss; for recovery of different types of hardware- e.g. hard drive recovery, SSD recovery, etc. see the main data recovery page).

There are many ways to lose data, but they can be separated into four different groups to help decide what approach is needed in recovering it. These can overlap to some extent in certain cases- all the same, they’re helpful in understanding that there can be various types of data loss that require different approaches in recovery.

Your data loss probably falls into one of the following categories.

Logical

This form of data loss occurs when the drive hardware is fine, but a mistake is made by either the computer or the software- or sometimes you. It’s called “logical” because it happens at the data/software logic level.

One example is when you delete an important file, then later realise that you made a mistake. That’s bad news, but the drive can’t be blamed. Or sometimes the part of your computer’s operating system (e.g. Windows) that keeps track of files makes a mistake, or (e.g.) the power is disconnected when it’s updating the catalogue or files. This can leave them in an inconsistent, half-updated state that can cause data loss and further corruption. None of this is a fault with the drive itself.

The silver lining here is that such data recovery normally doesn’t need hardware repair- in fact, if the hardware itself is okay, it can often be safely reused.

See the full article on logical data loss for more details and explanation.

Mechanical and Physical Failure

Mechanical faults, on the other hand, are definitely caused by problems with the drive itself!

“Head crashes” on hard drives occur when the head- which normally floats on an incredibly thin film of air- crashes into the drive surface for one of several reasons. This can cause massive damage to both the delicate head and to the equally delicate drive surface.

The infamous “hard drive clicking” problem is generally caused by a physical problem with the drive itself. The read/write head, unable to locate its position (often due to damage to the platter surface), attempts to return to a “known good” position and start again. If it hits the end of its run, it makes a “clicking” sound. When it repeatedly tries- and fails- to fix the problem this way, the unpleasantly familiar series of clicks is the result.

Electronic

Electronic failures are those caused (for example) by power surges, the use of incorrect power supplies, and so on- often with a noticeable “burning” smell.

Needless to say, if you’re getting a burning smell coming from anything in your computer, you should (safely) disconnect the power and not use it until you’re confident it’s safe to do so- if at all!

Generally speaking, electrical surges will destroy (or “fry”) electronic components. Quite how damaging this is can vary, but often some of the controller components can be damaged while (e.g.) the memory chips or hard drive mechanism itself may be intact and the data still recoverable.

Heart-Stopping

This is basically a catch-all for the really unpleasant scenarios. Cases like:

  • Dropping a hard drive or knocking it off the table
  • Fire damage
  • Water and flood damage

You can see why we’ve called these ones “heart-stopping”. There are endless variations possible- probably best for your sanity not to imagine them- so we can’t list them all (e.g. hyenas eating your backup tape drive). Needless to say, though, we’re the ones to help recover your data once disaster has occurred.