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the IT department

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Hard Disk or Solid State?

A hard disk drive is the most familiar type of storage device, present in all kinds of computer from laptops to servers and even mainframes. The most popular alternative is the Solid State Disk (or Solid State Drive), which we have been starting to see over the past couple of years – especially in the low-weight laptops – but which is best?

Hard Disk (HDD)


The HDD comprises a number of disks that typically spin at 5200 or 7200 RPM or even faster for high-speed data requirements such as video. A moving arm tracks across the surface of the disk, creating or detecting data coded as different areas of magnetism arranged in discrete tracks across the surface of each disk.

The read/write head “floats” very close to the surface of the disk but does not actually make contact – if it does, known as a ‘head crash’, the drive is essentially destroyed. Although it is sometimes possible to recover data from a damaged drive, it requires specialist equipment and skill and generally costs hundreds of pounds, at least!

HDDs have been around for a long time and are very reliable when you consider the precision engineering that is necessary and these days are incredibly inexpensive.

The control electronics built into HDDs is very sophisticated and will generally allow a disk to fail gracefully, giving a bit of time to replace it before it is too late.

Solid State Drive (SSD)

ssdBecoming more popular as capacity increases and price falls, the SSD is not a disk drive at all. In fact it has more in common with flash memory chips than disk drives and has no moving parts. SSDs are orders of magnitude faster at reading and storing data and because there is no need for powerful motors and actuators, they are much lighter and consume far less power.

The downside? Well, a solid state drive is still a lot more expensive than a disk drive of similar capacity. However, the advantages of speed, power consumption, and shock tolerance tend to outweigh the higher cost, particularly in mobile applications such as tablets and laptops, where weight is important.

In terms of reliability, the jury’s still out. Because they are relatively new to the mass market, 3 or 4 years compared to 30+ years for HDD, there is a dearth of reliable stats. Earlier devices were prone to early-life failures but the more recent ones are said to be very reliable. What does seem clear, however, is that the brand matters, with Intel and Samsung coming out on top.

You pays your money and takes your choice!

For speed of operation and weight, SSDs are the clear winner. If you are worried about cost or you want bigger capacities, perhaps the HDD is for you.

As for reliability, HDDs have a proven and well known failure rate and when they do fail, there is often sufficient warning to do something about it before you lose your data. They are particularly susceptible to shock. Affordable SSDs are a fairly recent development and certainly the earlier ones were not so reliable and tended to fail without warning. However, recent research suggests that a decent modern SSD, should last at least 10 years before wearing out and this is comparable with HDDs but there are many stories to be found of much higher failure rates. Brand seems to be an important consideration, with Intel and Samsung devices coming out on top.

Whatever your choice, never trust your data to a single drive, whether SDD or HDD and always, always take regular backups – and remember to test them!

eek a mouse

About the Author:

John Sanderson is the Chief engineer at the IT Department, a division of Clantec Solutions Limited,
helping individuals and small businesses with their IT challenges.

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