Q The hard drive in my iMac 27″ Quad-core failed after seven months, and was replaced under warranty. It now sits on a desk, on top of a floor that is not as solid as it should be, sometimes allowing some movement. Would that movement damage the hard drive, or should I batten the desk to the wall?

A You should avoid moving all computers when they contain a hard disk that is still spinning.

Some drives, notably those for laptops (normally 2.5″ disks), are designed to withstand greater jolts than those in regular desktop computers. This ensures that knocking a laptop when in use, or putting it on your lap, does not destroy the drive. However your iMac should have a 3.5″ drive which is probably not designed to cope with such substantial jolts, and should therefore be treated with respect.

Simply lifting an iMac up and moving it carefully before putting it down gently is not sufficient to crash the hard disk. However such innocent moves often do not go to plan: if you were to drop your iMac onto a hard desk or floor when the drive is spinning, that could readily develop sufficient g forces to crash the drive.

Physical disk crashes caused by excessive jolts are not nice. The classic injury is for the heads to crash against the spinning platters. As the latter are revolving at 7200 rpm or more, this completely destroys the surface of the platter where the impact occurs, can destroy the heads too, and the entire drive and its contents are normally lost.

Although specialist data recovery services may be able to salvage data at substantial cost, this is an experience well worth avoiding. Secure the surface on which you place your iMac to minimise the risk of disaster.

Updated from the original, which was first published in MacUser volume 28 issue 17, 2012.