Recovering data from a dropped hard drive can be challenging, but is possible in many cases. Often after being dropped, a hard drive will make a clicking noise, and no longer show up when plugged in. It is important to switch off a dropped drive ASAP, and not switch it back on again. This will minimise the damage and avoid making things worse.
Dropped Disk Damage
Damage to the delicate read/write heads is very common after a hard drive is dropped. Most portable drives will try to “park” the heads away from the discs if they detect a sudden motion, however this doesn’t always happen. Often the heads are left resting on the discs, so there is a good chance that a small area of damage will be caused. If the hard drive is repeatedly powered on in this state, the damaged heads will scrape more coating from the discs until recovery is impossible. If we receive the dropped drive soon enough then we can replace the damaged heads before they cause too much damage, and then try to work around the damaged area.
Although some desktop-size hard drives also have sudden motion sensors, most don’t. This means 3.5″ drives are likely to be damaged more by drops or falls. With 3.5″ drives, there is also more risk of motor damage when they receive a hard shock. The problem with motor damage is that the disc-pack is clamped on to the motor, and cannot be misaligned. This makes the repair very difficult. We have developed our own in-house equipment to deal with this type of problem, as we were unhappy with the solutions available.
Chances of Success
If the heads were able to park off the discs, there is a good chance of recovery. The drive will probably need some new heads and be checked inside for damage. It’s important that we only open a hard drive inside the cleanroom, so don’t try it at home. We’ve received many hard drives that would have been recoverable if they had not been opened before they arrived with us.
If the heads have hit the discs then the chances of recovery depends on how much damage was caused. Small dots of damage can sometimes be worked around, but any large scrapes or rings will instantly damage any replacement heads we install.
Motor damage can have quite a low success rate. If the hard drive has received enough shock to seize the motor, then it will probably have caused a lot of other damage, and may have even knocked the discs out of alignment. Discs cannot be simply realigned so that would be an unsuccessful recovery. In cases where the motor is damaged we will often be able to recover the data, but will usually also require a set of new heads.