A dropped hard drive or disk, particularly if it was running at the time can cause significant damage to platter surfaces and or the HSA head stack assembly as you would imagine.
Perhaps it was an external hard drive which was knocked over on the table? Worse still falling directly to the floor?
During R&D lab tests we have seen catastrophic failure to certain hard drives which are dropped from just 1″ while in operation.
Why does the hard drive become so damaged?
Spinning magnetic media operates at a typical rotation speed 7200 RPM (speeds vary on exact model) the HSA Head Stack Assembly literally files over the disk surface by the Bernoulli effect and has a distance of less than 1 micron, so any excessive horizontal movement can cause impacts to the surface.
The term is ‘head crash’ and can strike fear into the hearts of any who have heard those words and have important data on the drive.
Do not on any circumstances open the hard drive, ‘just to have a look’, as some have tried as this will compound the recovery further.
In a class 10 clean room environment a full and professional diagnosis can be made and a clear process can be developed as to secure a successful recovery of data.
The HSA will often need replacement, and this is not as simple as it first starts, as hard drives are unique and require exact replacement parts to be fitted, and it is not simply a case of contact the manufacturer for parts, because they do not sell such parts, a replacement hard drive with the correct MLC machine level code or DCM drive configuration matrix, site code and or relevant dates are required, no mean feat I can tell you, and requires a full time position to track down such parts.
Following a dropped hard drive many users attempt to restart the drive, again this is not a wise move as further damage can occur, for those that have attempted to spin up the drive they may hear a beeping like noise, this could indicate that the spindle is now seized, and for a modern 1-2 tb disk this is a very serious and complex recovery as a procedure called a ‘platter swap’ is now required, and as the name suggests it involves moving the damaged ‘patient’ platters to a good working ‘donor’ which has a free working spindle, this procedure must preserve the rotational alignment of all disks and in some instances eccentricity issues must be catered for.
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