What is an SSD (Solid State Drive)

Solid State Drive

Its a sure bet that 99% of you reading this article on a PC will have a hard drive installed inside your computer. The hard drive has been with us for decades and has never been challenged to storage throne. The hard drive has been generally reliable cost effective and comes in very large capacities. These traits have meant the hard drive has been able to be a solid part of computing for many years. Now we have the Solid State Drive (SSD) sometimes referred to as the Solid State Disk with the same acronym. Solid state drives use non volatile (keeps data after power is removed) flash memory so unlike the hard drive it has no moving parts, this has many benefits that we will go into later. The SSD started of life as high end storage solution for businesses that required an extra tier of fast storage such as for a database on a server, where many people would try and access the data on the drive simultaneously. With a hard drives spindle system this would take some time to keep fetching the data from different parts of the disk. The SSD stores the data electronically and can fetch the required data much faster.

Advantages and disadvantages of the Solid State Drive over the Hard Drive

Data Speed – The main advantage of the Solid State Drive is the speed in which in can retrieve the requested data. because hard drives are a mechanical system they are limited to the speed in which the head can be placed at the correct part of the disk, while technology of hard disk drives has improved a great deal in terms of seek times and transfer rates, they are no match for the electronically stored data of the SSD. Flash memory can be accessed almost instantaneously with no regard to where on the drive the data is located.

Fragmentation –  Fragmentation is when parts of files have to stored in different locations on a disk. This happens because the constant writing moving and deleting of files of different sizes means only patches of a disk are available for the computer to write to. A Solid State drive has no problem with fragmentation because it has no change in performance wherever on the disk data is stored, while a hard drive much physically be aligned to the correct area of the disk for every request. If each file is split into multiple locations this will slow the hard drive down as it seeks out each part of the file in turn. Defragmenting a hard drive will improve its performance, while defragmenting an SSD will only serve to lower the lifespan of the drive as the NAND flash cells have a limited life span.

Start up time – With no moving parts to “spin up” the solid state drive is ready to be used almost instantly, while the Hard Disk Drive must get up to its rotation speed before it starts to transmit data. With the Hard Drive you would have to wait for this small delay every time your hard drive powers down and stops spinning.

Power Consumption – While the power consumption of SSD’s and hard drives does vary by model, the general consensus is that a Solid State drive will use between a third and half of the power of a comparable hard disk drive. This again is mainly down to the lack of moving parts in the SSD.

Lifespan – The Flash cells in a solid state drive do have a limited life span, they can be written to millions of times but in heavy use they can start to fail, modern SSD’s have controllers that make sure that each cells is used equally which extends the life of the products into decades, the hard drives magnetic storage solution does not have a physical limit to the amount of reads/writes, its life depends on the condition the drive is kept in.

Reliability – The flash memory is not prone to sudden failure and be classed as the more reliable product. Once again due to the lack of moving parts SSD’s do not very often fail and can survive a certain amount of shock damage without being rendered inoperable. A hard drive can be a brittle piece of machinery which is finely balanced. They can be susceptible to sudden failure, as well as not well equipped against shock or vibrations. it should be noted that hard drives are not considered “unreliable” they simply have more potential to go wrong than the solid state drive.

Heat Dissipation and cooling – We find ourselves back to issue of the moving mechanical parts, anything that moves creates a certain amount of heat and hard drives can get quite warm, sometimes they also require extra cooling in order to keep them from overheating, at the very least if you are using multiple hard drives in your computer, you may want to think about upgrading your case cooling. Hard drives can fail with excess heat. SSD’s do create there own heat but due to the less power consumption and lack of moving parts, they do not produce as much heat in your system, they can also tolerate much higher temperatures without damage.

solid state drive and hard disk drive comparisonNoise – What could be the factor behind noise? ah yes that’s right, moving parts. another area where the hard disk drive unfortunately falls behind. the noise of disk rotating at around 7200rpm is going to cause some noise, add to this the noise of a fan to cool the hard drive and some drives can sound pretty horrendous at times. Solid state drives can operate in near if not complete silence. This makes the SSD a great option if you are considering building a home media PC and wish to watch a lot of TV/films etc.

Weight – SSD’s weigh very little in comparison, most of the weight comes from the packaging as the memory itself and the controller cards weigh a negligible amount. hard drives are much more bulky and larger capacity drives with multiple platters can weigh a fair amount. New ultra book laptop computers can be found with SSD’s built in as they help with the reduced weight and mobility of laptop computers.

Storage Capacity – The storage capacity of hard drives are nothing short of huge, they can range up to about 4TB as I write this, the solid state drives can be available i up to 2TB but they are non common, most SSD’s are available in sizes around 256GB due to the cost, see below.

Price – Ultimately, this is what it all comes down to in the end. It will be no surprise that the newer technology of the Solid State Drive does cost considerable more than the hard drive, as the SSD becomes more popular however the price will of course drop as they will be manufactured in greater numbers. As an example from Wikipedia, the cost per GB of NAND flash memory in 2011 was around $1, while the cost per GB of hard drive storage was around $0.05.

Its quite clear of the advantages of the Solid State Drive over the common Hard Drive, however the sheer expense of large solid state drives makes them unsuitable for large home computer storage. because of this i don’t think the hard drive is dead, far from it in fact. The speed increases from a solid state drive are noticeable but are the actually required for the home user? many would say not, while enthusiasts will always want the best tech available, and the SSD certainly is the best available out of the two platforms.

The best uses for a Solid State Drive in a home PC

We’ve just said that the expensive nature of a large SSD for the home users makes it impractical to be used as a direct replacement of the hard drive. but that doesn’t mean that they are not useful in a smaller capacity. A disk large enough to be used for full storage purposes is easily going to cost hundreds of pounds (circa 2012) but the smaller capacity drives such as 64GB and 256GB are becoming more popular and therefore the price of them is being reduced. A practical use for this type of drive is as a boot up drive for the home PC. Couple this with a secondary hard drive and you can have your operating system boot from the solid state drive and also have the large and very well used swap file on the fast drive as well. This will definitely speed up Windows boot times as well as making Windows (or another operating system) run faster in general use. To the left is a video of a Windows 7 machine booting with a solid state drive. (model OCZ Agility 3). The video shows the speed in which a computer can be booted and in this video 150 applications loaded. It shows that when a computer is first started that the Hard disk drive is the bottleneck which causes computer slowdown.

Similarities with the SSD and Other Flash Memory

There are many different varieties of flash memory in terms of end product, however they all come from the same basic principle of storing data electronically. Flash memory however has to be adapted to suit the environment it is being placed in. For example you can get SD cards, SD cards are a type of flash memory but are designed to be inserted into small peripherals and to be inserted and removed repeatedly, Solid State drives are designed to have more capacity but are bulkier and tend to be permanently fixed inside the PC, There is also the USB memory stick, which in essence is simply a flash memory card inserted into a casing with a USB connection for reading. The USB memory sticks are no where near as fast as the SSD’s but this is down to the limitations of USB and not down to the flash memory.

SSHD’s (Solid State Hybrid Drives)

SSHD’s bridge the gap between Solid State Drives and the traditional Hard Drive by combining the best of both. In a single casing you can have your bulk storage space from your hard drive and also have a section of high speed NAND flash memory like an SSD incorporated so that the most accessed data can placed in the high speed storage. This speeds up application startup and shutdown times and reduces initial boot up times. Read more about SSHD’s.

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