HDDs+vs+SSDs


 * HDDs vs SSDs **

There are many types of digital storage, but in the end, the most popular forms are the good old hard drives (HDDs) and new solid-state drives (SSDs). These are internal storage devices that are the backbone of most if not all storage applications, ranging from external hard drives, NAS servers, to even data centres, which basically host the entire Internet, including cloud storage services. (Memory sticks and thumbdrives are just popular derivatives of solid-state storage.)

It's hard and complicated to explain in detail the difference between the storage and system memory (or just "memory" or RAM) in a computer.
 * Storage vs. memory**

In a nutshell, storage is where the information (such as Word documents, photos, movie clips, programs, and so on) is stored. In a computer, the whole operating system itself, such as Windows 7 or Mac OS, is also stored on the internal storage device.

Storage is non-volatile, meaning that the information is still there when the host device (a computer, for example) is turned off and becomes ready again when the device is turned back on. It's like a book or a paper notebook that's always there, ready for you to read or write on.

System memory, on the other hand, is where information is being processed and manipulated. Data in the system memory is volatile, meaning when the computer is turned off, it's gone; the memory becomes blank as if nothing had been there before. It's somewhat like the short-term memory part of your brain, where images or ideas are being formed and processed when you read a book, those that disappear the moment you stop reading.

There's a strong relationship between system memory and storage. The Word document that you're working on, for example, is in the computer's memory. When you save it, a copy of it now resides on the computer's storage (the hard drive). When you close Microsoft Word completely, the document now only resides on the hard drive (storage) and no longer in the memory, until you open it again.

All this means, you generally never experience storage. Everything, including the operating system, that's presented to you on a computer's screen or via the speakers actually take place in the system memory. Before it gets there, however, it needs to be loaded from the computer's storage device into the system memory. So the larger and faster system memory the computer is equipped with, the more quickly the information becomes ready and the more you can do with a computer at a time (multitasking).

Of course, memory is just one of many factors that decide a computer's performance. Another factor is the storage itself, which mostly likely is either a hard drive (aka, hard disk) or a solid-state drive.

__**Hard drive vs. solid-state drive**__ A modern hard drive is very different from earlier generations, which dated back to the late 1950s. However, essentially, the basics remain the same. It's a box that contains a few magnetic disks (known as platters) attached to a spindle, very similar to a spindle of blank CDs or DVDs. Each of the platters has a reading/writing head hovering on top. As the spindle spins, the head moves in and out to write or read data to and from any part of the platter, on tiny information-recording unit called "data track." This type of access to information is called "random access," as opposed to the inefficient "sequential access" found in the old and obsolete types of storage, such as tape.

While the concept is rather simple, the inside of a modern hard drive is a world of advanced nanotechnology. This is because as hard drives' storage capacities increase while their physical sizes remain the same, the density of information written on the platters becomes so great that if we use measurement units, such as foot or inch, to talk about certain parts of a hard drive, we'll have to deal with decimal numbers of unimaginable proportions. Instead, we need to use nanometers. One nanometer equals 1 billionth of a meter (a meter is about 3.3 feet )

Inside a regular 2.5-inch laptop hard drive, the WD Scorpio Blue, for example, the gap between the head and the platter is just a few nanometers. The two can never touch each other--or else the drive will be "bricked"--and note that when a hard drive is at work, its platters spins at 5,400rpm. Desktop and high-end laptop hard drives spin even faster at 7,200rpm or 10,000rpm.

To put this in context, if we enlarged the Scorpio Blue by 13,000 times, the platter would look like a circular race track about 3.3 miles in diameter; a data track would be about 0.4 inch in length, and the head would be about the size of a go-cart. When the hard drive is in operation, this go-cart would be flying on the track less than the thickness of a human hair above it, at the speed of some 3.4 million miles per hour.

It's just amazing how hard drives don't crash every day. Most of them actually last for about five years of continuous usage.

An SSD, on the other hand, has no moving parts. Similar to system memory, SSDs are microchips designed to store information. However, these are non-volatile memory chips that can retain information the way hard drives do.

On the outside, a standard SSD looks just like a regular 2.5-inch hard drive and it also works in any applications where hard drives are used. The fact that it has no moving parts means that an SSD is much more efficient in terms of energy usage, more durable, quiet, and much faster than a hard drive. For this reason, a computer that uses an SSD as the main storage device boots and shuts down very fast and can resume from sleep mode instantly. Software applications, including heavy ones like a 3D game or video-editing application, also take significantly less time to start and operate, compared with when the computer uses a hard drive as the main storage.

There's a big catch, however: SSDs are currently much more expensive than a regular hard drive of the same capacity, disproportionately more expensive than they are faster.