While HDDs are sensitive to vibration which can cause data access delay, one of the advantages SSDs have over HDDs is that they have no moving mechanical components which preserves them from any bad effect caused by shocks and vibration.
It has been claimed by some SSD vendors that shock may cause the head of HDD to crash. Although we cannot find a solid proof to support this claim, the proven fact is that an HDD’s actuator (the read/write head mechanism) can be dislodged away from its track, causing a one-rotation delay before it can get back to its original position and access the desired sector.
So how much of a problem can this be? Is it an issue to worry about?
Well, imagine that the tracks on a terabyte HDD are only about 100nm apart (that’s one ten-millionth of a meter) which is really a very short distance. Now how much vibration do you think is required to move the actuator that tiny amount of space? It is not that much. So disk array designers are very interested in shock isolation to ensure that the movement of an actuator from one single HDD is less likely to vibrate an adjacent HDD.
For an average PC user this is not going to be of any problem, even in the data center this may not pose significant problems. But in other environments, like in industrial applications, it’s justified why many engineers tend to use an SSD instead of an HDD, even if the high speed of an SSD is not required by them.