What’s the difference between… SSD and HDD?
Q
I use your Jargon Buster page, so I know that SSD means solid-state drive and HDD means hard-disk drive. However, I’m afraid I’m still not really clear what the difference is. I’m old enough to remember claims of solid-state radios being better than old-fashioned wirelesses but that never meant much to me either. Why is ‘solid state’ (whatever that is) better than something that isn’t? And why are SSDS specifically better than HDDS? Harold Foster
A
Fundamentally, ‘solid state’ means a lack of moving parts — a device that’s all electronics, and nothing mechanical. So, an SSD means a drive where nothing inside moves. By contrast, a hard-disk drive (or HDD) has numerous parts that function mechanically, including disk platters that spin constantly and little read/write heads that dart across the platters all day long.
With no wear and tear caused by mechanical activity, solid-state devices tend to last much longer than their mechanical counterparts. With SSDS in particular, there’s also simply fewer parts that go wrong: they’re really little more than a circuit board with some memory chips.
SSDS are also a lot faster than HDDS, by dint of the fact that they’re entirely electr electronic. When the PC wants a bit of data from an HDD, the drive’s read/write arms have to move to a particular po point on the platter, and th then wait for the relevant area of the platter to spin beneath the read/write head. The data is then read magnetically, converted to an electrical signal and sent to the computer.
Of course, all this happens incredibly quickly. HDDS also operate with unimaginable accuracy, but the endless mechanical movements add up. By contrast, when an SSD is reading or writing data every aspect of the operation is electronic, so there’s no waiting for mechanical or magnetic parts to do their job — and that’s why SSDS tend to be an order of magnitude faster than HDDS. Want to know the difference between technical terms? Email us at noproblem@ computeractive.co.uk.