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)

Random read performance has never been SandForce's biggest strength and even Intel couldn't massively improve it with its own firmware. The SSD 335 is in fact slower than the SSD 330 here.

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

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

Random write speed at small queue depths is also slower compared to the 520 and 330, although at queue depth of 32 the difference is negligible. 

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)

Sequential read performance is identical to SSD 330, but sequential write speed is slightly slower. What's notable is sequential write performance with incompressible data: the Intel SSD 335 manages to beat both the 520 and Corsair's Force GS by a noticeable margin.

Inside the Intel SSD 335 and Test Setup AS-SSD Incompressible Sequential Performance


View All Comments

  • meloz - Tuesday, October 30, 2012 - link

    >After Anandtech's 840 Pro review sample died, I'm not super inspired with confidence about the plain 840.

    Oops, I had almost forgotten about that, thanks for the reminder.

    Damn, all SSD manufacturers suck in their own ways.
  • jwilliams4200 - Thursday, November 01, 2012 - link

    I'm disappointed that there hasn't been any more information on that 840 Pro that died.

    Anand should really post some more details. Like what it was doing just before it died, the symptoms of how it failed, whether the SMART parameters could still be read, etc.

    Also, Anand should be hounding Samsung to get back to him about it, if they haven't already. The 840 Pro is apparently shipping on Nov 6. If Samsung has not been able to diagnose the problem and report back by then, it looks bad for Samsung.
  • Kristian Vättö - Thursday, November 01, 2012 - link

    Anand was filling the drive with sequential data (preconditioning it for our enterprise tests) and it just died in the middle of the run. After that it was no longer recognized in BIOS, not even when connected using USB to SATA adapter.

    As far as I know, Samsung has not gotten back to us about it yet but let me ask Anand and see if he knows more.
  • jwilliams4200 - Thursday, November 01, 2012 - link

    Thank you for the additional information.

    I am highly interested in what Samsung has to say about the failure. It seems to me that anandtech should be able to put some pressure on Samsung to give them a thorough failure analysis in a timely manner, or else anandtech will report that Samsung was unable to explain the failure and that looks bad for Samsung.
  • mmonnin03 - Tuesday, October 30, 2012 - link

    The flash on SSDs arent going to get more reliable. ECC basically scales exponentially as the process dimensions keep shrinking. As the lines get closer and closer, the number of electrons holding the charge becomes harder and harder to measure. Each cell is 2 bits, so 4 different amounts of electrons need to be measured. Errors occur more frequently and get fixed. And that's not going to make the NAND any faster by going smaller. SSD speed/reliability improvements will/have come at the controller level. If you truly want a reliable SSD, go 34nm SLC. Its still being produced. Reply
  • jeffrey - Monday, October 29, 2012 - link

    Between the Samsung 840 Pro dying during testing and now the endurance issue testing Intel's 335, I believe OCZ should get some more credit for their Vertex 4.

    Everyone wants to mention Intel, Micron/Crucial, and Samsung for SSDs, but the Vertex 4 deserves to be there too.
  • josephjpeters - Monday, October 29, 2012 - link

    Endurance will play a larger role in differentiating future SSD's as the industry continues to move to smaller NAND geometries.

    I'm interested in seeing OCZ's Vector which will use 20nm MLC NAND. It'll be a big test for OCZ to see how their endurance technology stacks up against the competition (or lack thereof in the consumer space).
  • Samus - Monday, October 29, 2012 - link

    I've had my Intel SSD320 160GB for about two years, use it daily, and still have only written 10.6TB to it and the MWI is still 100%.

    Either way you look at it, this drive will last the average user a decade easily, even with less than 1000 P/E
  • IntelUser2000 - Tuesday, October 30, 2012 - link

    This is false: "Based on the data I gathered, the MWI would hit 0 after around 250TB of NAND writes, which translates to less than 1,000 P/E cycles."

    There is a forum that exclusively tests SSD endurance and Intel drives last far past the MWI of 0. In fact, after it reached zero, it started counting up. I remember the original X25-M lasting until the second MWI is significantly greater than 25(it could be 50 I don't remember).

    They thought that after the Media Wearout Indicator reached 0, the drive would die. In fact, none of the drives did. NONE.

    Even 240TB is hell of a lot. My X25-M has 7.6TB written to it and I had it since the year the drive was announced. At this rate, I'll be 30 years older by the time it reaches that point. So its a needless worry about nothing.

    Contrary to Platter HDDs, which die off slowly and more and more data gets corrupted and gets slower and slower until you notice that the drive is dying. Less than 5 years for lot of people around me too.
  • Kristian Vättö - Tuesday, October 30, 2012 - link

    I did not say the drive will die after the MWI hits 1. In fact, I said the opposite:

    "Even after it has hit 1, it's likely the drive can still withstand additional write/erase cycles thanks to MLC NAND typically behaving better than the worst-case estimates."

    The problem here isn't that 1,000 P/E cycles isn't enough for a consumer, but the fact that there seems to be a huge difference in endurance between 20nm MLC and 25nm MLC if our data is correct. Intel claimed that there is no difference, both are 3,000 P/E cycles, but our data contradicts with theirs. Given that the SSD 335 doesn't bring any immediate price cuts, you are getting a worse product for the same money compared to the SSD 330.

    It's of course possible that there is a simple firmware bug which reports wrong MWI or NAND writes, but at least so far Intel has not said anything to suggest that.

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