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Solid State Drives and why you should invest

Computers weve been buying for years now have been running on conventional Hard-Disk-Drives (otherwise known as HDD's) - the benefit today of these types of drive is the large amount of storage, as of 2015 you can get 6-8Tb (TeraByte) HDD storage space (enough to store around 1600 2 hour Full High Definition 1080p Movies) and you can get them at a reasonale price, and that a lot of storage, the only issue is these drives can suffer from fragmentation and are certainly not as fast as a Solid Sate Drive (also known as SSD's).

HDD's have moving parts such as the spinning magnetic platters and read/write heads / SSD have no moving parts and so use a heck of a lot less energy saving you money, they say over the course of 2-3 years an averaged sized SSD has paid for itself in the money you save on energy bills.

What is Fragmentation?
over time the files on your computers hard-drive become fragmented which causes it to be slower, this happens because when you save a file it saves it in the nearest location of free space of the same size with some extra thats known as padding in case you add extra to the file, however the padding calculation is not always right as its up to the user how he/she expands that file...i.e. adding content that is larger than the space the file is in, what happens next is the extra block of information is stored on another part of the disk meaning now that one file has become multiple fragments across your hard-drive...now magnify this with program installation and use, web browsing etc...over time the drive will become heavily fragmented and thus slower - this is why windows have built in Defragmentation Tools (or you can get better ones such as Raxco PerfectDisk which has excellent file placement algorithms).

So what is a Solid State Drive and why are they better?
Basically, a Solid Sate Drive (or SSD) is made of NAND memory chips and has no moving parts saving energy, it has memory in the drive instead of a spinning magnetic disk, as it uses NAND or V-NAND memory chips this means it can read the data many thousands of times faster...for example your typical HDD may read data (not fragmented) at about 160MB/s sequentially, perform about 90-100 Input/Ouput Operations per Second (known as IOPS) and have a response/access time of 5-8ms (meaning it takes that long on average for the head to move to the next position needed on the drive). SSD's on the other hand (if using a SATA one that plugs into the same SATA port as your HDD) can read data up to 550MB/s (on a SATA-3 port, 300MB/s limit on a SATA-2 port). Also SSDs do not suffer from fragmentation because of they way they operate, it doesnt matter if the file is split in 3 it will still take the same time to load, this is why you should never defragment an SSD as your wasting your writes (see below).

Two of the most important factors are that they can perform up to 100,000 IOPS (compared to 90-120) and have access times such as 0.05ms, it these two combined that make your system really quick and load up in seconds, the faster sequential reading (like the 550MB/s I mentioned before) is good for loading large files very quickly; such as games or photoshop RAW files or AutoCAD and do so 3-5 times faster than a non fragmented HDD, also because they have no moving parts they are 100% silent.

Thats just the SATA-3 Interface versions I've mentioned, SSD's are now so fast they are limited by SATA-3 because the fastest it can go is 600MB/s, you can get SSD's that are PCE-I, NVMe or M2 and slot into your motherboard allowing it to use PCI-E lanes which (depending on which port you use) has several thousands of MB/s of bandwidth and give you as much as 200,000 IOPS and slightly less access times.

The only bad thing about SSDs is they have limited write capability, typical MLC flash drives have an endurance rating of 3,000 P/E cycles (Program/Erase), TLC based flash drives have an endurance rating of 1,000 P/E cycles, this means you can write to the entire drive 3000 or 1000 times respectively before it should start to fail. Tests have been done and its now confirmed that SSD's will last quite a bit further than the ratings above, one website has been testing SSDs by writing to them constantly and they managed to reach an average of 3 times more than the ratings qouted above for MLC and TLC flash drives, Reads are unlimited, the write limitation is due to the cell being charged and uncharged repeatedly billions of times.

As SSD's are a relatively new technology they do cost more than HDD's, but as more people buy them and time goes on they will get cheaper, at time of writing you can get a excellent performing 250GB Samsung 850 EVO 'TLC' SSD of 250Gb for about 70-80, or you can pay about 40 extra for the Pro version which is an MLC drive and has more endurance/write capability.


Whats TLC and MLC and whats the difference?

There are 3 types of SSD: SLC (Single Level Cell), MLC (Multi-Level Cell) and TLC (Triple Level Cell) - these refer to the amount of bits stored in a cell, where SLC=1, MLC=2 and TLC=3. SLC drives dont really exist in the mainstream market as the cost of them is so expensive its not really viable, this because you can still get similar performance from MLC and TLC drives by use of an SLC cache, the more bits stored in a cell means more write amplification and lower endurance (write capability), this is because cells have to be re-written with extra data quite a bit, SSDs employ 'wear-levelling' algorithms to try and ensure the cells of the drive are written to in equal amounts giving you better endurance. MLC drives will last longer than TLC drives, but TLC drives are much cheaper, also the bigger the drive - the longer it will last as it has more cells to write too. Most SSD's come with 5-10% extra storage onboard thats 'hidden' and used for reserve when cells start to fail, this means the size of your drive doesnt decrease until its used up all the reserve, this gives you time to consider replacing the drive.

So, if you have upgraded to an SSD I would recommend you do so...at time of writing the Samsung Pro range tend to be the best

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