The Truth Behind SSD Performance Numbers
As someone who has purchased many different storage devices (HDD, SSD, flash drive, etc.), I have experienced first hand the confusion that can come from all the numbers we are bombarded with.
IOPS! MB/s! Sequential! Incompressible! they yell at us with numbers to back up their lofty claims of ever increasing performance. But what do all of these things mean? Some people may give up and just get the one that has the largest numbers plastered on the box. Hopefully after reading this article, that will not be you.
Sequential vs Random Performance
One of the largest performance differences you are going to see with any drive is when working with sequential data vs random data. The term sequential data is fairly self explanatory. It’s stored linearly, that is, it’s all side-by-side or very close together. Random on the other hand is just that, random. The data is scattered and therefore the drive has to work harder to access it. Think of the data like marbles. If you place 100 marbles in a pile, you could quickly and easily pick them up and put them away. But if you were to take those marbles and throw them across the room, you’ll be picking up marbles all day.
So now that you understand what each term means you are probably wondering, “which one is more important?” And that is where it gets tricky. It is impossible to put a black and white answer on it and say that one is always better than the other. It really depends on what you will be doing with the drive. Sequential data is generally used with things like copying or accessing stored files. So if you plan on using your SSD for working with or often transferring large amounts of files such as pictures, movies, etc., then sequential would be pretty important to you. Random data is what is generally accessed by the operating system. The files are usually small and spread out which really puts a strain on the drive. For general, everyday purposes, random performance is what you are going to notice.
Hopefully you now understand what sequential and random data is and how it affects your computing. With that out of the way we move on to read vs write.