Knocked hard drive off desk

My son recently knocked our external USB hard drive off the desk. Now when I plug it in it makes a clicking noise and is no longer detected by the computer. Is this something that can be fixed?

Dave, Toronto

Hi Dave,

We recommend you immediately disconnect the drive if you still have it attached. By leaving it attached you are potentially causing more damage and reducing the change of recovering data.

To know what is going on you need to understand the basics of how a hard drive works. While solid state drives are becoming more popular and dropping in price there usage is still well outnumbered by traditional hard drives. In this case a solid state drive would most likely survive without damage so we are going to talk about traditional hard drives sometimes referred to as rotating disks.

In a hard drive you have platters. There are generally between 2 and 4 depending on the size of the hard drive. These platters rotate at between 5200rpm and 7200rpm on a desktop however on servers they rotate at up to 15000rpm

These platters have a magnetic surface on the top and bottom and are stacked on a single spindle. For each platter surface there is a read/write head that is attached to an actuator arm. The arm moves the read write head across the disk to access data similar to how a record player has a read arm that moves across a record. The major differences being that the actuator moves the heads in both directions across the platters and the heads don’t touch the disk they float as little as 3 nanometres above the disk.

The read/write heads act similar to how a cassette player works. They measure changes in magnetism on the platter however at a much finer level.

What most likely happened when the drive was knocked off the desk was that the heads touched the platters. This damages the platters and the heads. Generally the platters will have the magnetic surface scratched off so the areas that are scratched can no longer be read. Depending on how sever the damage data may not be able to be recovered.

The reason we recommend turning off the drive straight away is that the heads may be damaged in a way that they are still making contact with the platters causing more damage.

In a scenario like this we send the hard drive to our partner in Sydney. Hard drives can only be opened in specialised clean room environments otherwise dust will get in and cause more damage.

When it comes to physical damage to a drive a working identical model drive is cannibalised. They will take the disk platters out of your drive and put it in the functioning drive. They will then run software utilities over the drive to attempt recovery of your data.

This can cause data recovery to be expensive when physical damage is caused.