Understanding SSD Advertised Performance and Its Purchase Implications – An SSD Primer

Understanding SSDs Performance and Implications

Today’s SSD close up is going to teach us the most valuable thing we can ever learn about an SSD.

This is the fourth paper in a series of articles that explain the benefits, types and components of a solid state drive and will go so far as to make up our SSD Beginners Guide . Each article is designed to be easily understood and will enable the reader to become proficient in every aspect of the SSD as it relates to their specific computing needs.


Learning of a new technology and what it can do for us as consumers is somewhat similar to walking into a room blindfolded only to learn that the lights are out once the blindfold has been removed.  Try to find the light switch now right?  The world of solid state drives is no different as many are now buying Ultrabook computers only to have to come here to learn what an SSD is and why their new system hasn’t any hard drive.  Then again many may be here having an idea and hoping to migrate from a hard drive to an SSD.

Solid state drives are an amazingly fast move forward in the world of computers and, unfortunately, their purchase is much the same as we described above where consumers purchase blindly based on high performance numbers that they will never use.  This article is written to dispel the fallacies of ‘high sequential’ speed advertisement and help you along with a key SSD performance speed that you should be looking at in your SSD purchase, the one that will demonstrate very visible computer upgrade.

We are not exaggerating when we state that this is probably going to be the single most important piece of information you will ever learn about solid state drives.


Lets get right to the point shall we?  Take a little look at these performance scores and tell me what SSD  you would buy.
Ok… A few of you got it but I am disappointed in most so, lets try again.  Look carefully at the left performance results below and then the right.  Which setup would you believe will result in faster visible performance for the typical user?

Thorough examination should have resulted with your selection of the result on the right. No? I know, I know¦ Some of you are about to write me off as a lunatic and and find another article to help out with your purchase and, in fact, I even cheated a bit by using the performance score of an old RAID configuration to serve my purpose a bit further.  I’ll make you a deal.

Give me just a few minutes and I will change your mind completely  to the way you look at the performance of a solid state drive.


When first considering the purchase of an SSD, most will immediately look at performance specifications in order to determine what SSD is best. Unknowingly, they will quickly choose in awe of lightning fast speeds such as 550MB/s read and 520MB/s write that we are seeing in today’s solid state drives. After all, a SSD with a speed of 520MB/s must be faster than one capable of only 415MB/s right?

The answer is both yes and no.  A bit of an understanding of disk access percentages is necessary to be able to intelligently decide specifically what SSD is best for you.  Many may have seen an older version of this article where the disk access results were slightly different than we see below.  I believed it imperative to attain my own test sample and the following results were attained at the time of this article.

Top 5 Most Frequent Drive Accesses by Type and Percentage:

  • -4 Read (8%)
  • -4K Write (58%)
  • -512b Write (5%)
  • -8k Write (6%)
  • -32k Read (5%)

Top 5 account for: 80% of total drive access over test period

Largest access size in top 50:256K Read (-1% of total)

Using Microsofts Diskmon, I simply monitored my typical computer usage in doing things such as using the internet, running applications, playing music etc.  In short, I did my best to recreate the computer use of a typical user and then used the program to break down the percentage that specific disk transfer speeds were being utilized. The above results were calculated through a ten minute test period during which results were supplied throughout the test.  This is a simple test that anyone could recreate once they have downloaded the software.