Random Read/Write Speed

The four corners of SSD performance are as follows: random read, random write, sequential read and sequential write speed. Random accesses are generally small in size, while sequential accesses tend to be larger and thus we have the four Iometer tests we use in all of our reviews.

Our first test writes 4KB in a completely random pattern over an 8GB space of the drive to simulate the sort of random access that you'd see on an OS drive (even this is more stressful than a normal desktop user would see). I perform three concurrent IOs and run the test for 3 minutes. The results reported are in average MB/s over the entire time. We use both standard pseudo randomly generated data for each write as well as fully random data to show you both the maximum and minimum performance offered by SandForce based drives in these tests. The average performance of SF drives will likely be somewhere in between the two values for each drive you see in the graphs. For an understanding of why this matters, read our original SandForce article.

Desktop Iometer - 4KB Random Read (4K Aligned)

Desktop Iometer - 4KB Random Write (4K Aligned) - 8GB LBA Space

Many of you have asked for random write performance at higher queue depths. What I have below is our 4KB random write test performed at a queue depth of 32 instead of 3. While the vast majority of desktop usage models experience queue depths of 0 - 5, higher depths are possible in heavy I/O (and multi-user) workloads:

Desktop Iometer - 4KB Random Write (8GB LBA Space QD=32)

Sequential Read/Write Speed

To measure sequential performance I ran a 1 minute long 128KB sequential test over the entire span of the drive at a queue depth of 1. The results reported are in average MB/s over the entire test length.

Desktop Iometer - 128KB Sequential Read (4K Aligned)

Desktop Iometer - 128KB Sequential Write (4K Aligned)

AS-SSD Incompressible Sequential Performance

The AS-SSD sequential benchmark uses incompressible data for all of its transfers. The result is a pretty big reduction in sequential write speed on SandForce based controllers.

Incompressible Sequential Read Performance - AS-SSD

Incompressible Sequential Write Performance - AS-SSD

The Review AnandTech Storage Bench 2011
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  • UltraTech79 - Sunday, April 15, 2012 - link

    lol boot time and how fast it loads a program? They **ALL** load windows in about 15 seconds from a clean install and all programs open in less than 3 seconds. Photoshop maybe 4. That would be the most retarded benchmark I have ever heard of doing to get a real grasp on how fast these things are and the actual difference between them.

    If you understand anything about this stuff, you can determine real world performance from the numbers given. This isnt the old days with screwed up random reads anymore. Look at the I/O ability and get with the program.
  • AnnonymousCoward - Monday, April 16, 2012 - link

    If they **ALL** load Windows and boot programs at the same speed, what does that say about all these graphs that show alleged large differences? (it says they're bunk, misleading, and stupid) Why do you defend synthetic benchmarks that have no relevance to reality?
  • mikbe - Wednesday, April 11, 2012 - link

    "Moore's Law ensures that large SSDs can be delivered in small packages."

    Moore's Law is an inductive observation not an actual law of physics so it doesn't ensure anything.
  • AnnonymousCoward - Wednesday, April 11, 2012 - link

    That's also what I thought when I read that.
  • UltraTech79 - Sunday, April 15, 2012 - link

    Oh shut up.
  • spooky2th - Tuesday, April 24, 2012 - link

    Boy, would I like to win one these boards! It would be a nice start to a new build.
  • asawyer13 - Tuesday, June 26, 2012 - link

    I am looking at purchasing a higher end Dell XPS 15 laptop. It comes w3rd gen I7 cpu, and 1tb 5400 rpm drive + 128GB mSata drive.

    Would it be possible and does it make sense to replace the 1TB 5400 drive with a Crucial m4 512GB SSD???


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