Performance Consistency

Performance consistency tells us a lot about the architecture of these SSDs and how they handle internal defragmentation. The reason we do not have consistent IO latency with SSDs is because inevitably all controllers have to do some amount of defragmentation or garbage collection in order to continue operating at high speeds. When and how an SSD decides to run its defrag or cleanup routines directly impacts the user experience as inconsistent performance results in application slowdowns.

To test IO consistency, we fill a secure erased SSD with sequential data to ensure that all user accessible LBAs have data associated with them. Next we kick off a 4KB random write workload across all LBAs at a queue depth of 32 using incompressible data. The test is run for just over half an hour and we record instantaneous IOPS every second.

We are also testing drives with added over-provisioning by limiting the LBA range. This gives us a look into the drive’s behavior with varying levels of empty space, which is frankly a more realistic approach for client workloads.

Each of the three graphs has its own purpose. The first one is of the whole duration of the test in log scale. The second and third one zoom into the beginning of steady-state operation (t=1400s) but on different scales: the second one uses log scale for easy comparison whereas the third one uses linear scale for better visualization of differences between drives. Click the dropdown selections below each graph to switch the source data.

For more detailed description of the test and why performance consistency matters, read our original Intel SSD DC S3700 article.

SanDisk Ultra II 240GB
Default
25% Over-Provisioning

The IO consistency of the Ultra II is not too good. At steady-state it averages about 2,500 IOPS, whereas MX100 and 840 EVO manage around 4,000-5,000. However, what is positive is the fact that it takes about 200 seconds before the performance starts to drop, which is mostly due to the fact that the Ultra II does not provide as many IOPS in the first place.

Since we are dealing with a value client drive, I would not consider the IO consistency to be a big issue because it is very unlikely that the drive will be used in a workload that is even remotely comparable to our performance consistency benchmark, but nevertheless it is always interesting to dive into the architecture of the drive. While the Ultra II is not the fastest SSD, it is still relatively consistent, which is ultimately the key to a smooth user experience.

SanDisk Ultra II 240GB
Default
25% Over-Provisioning

 

SanDisk Ultra II 240GB
Default
25% Over-Provisioning

 

TRIM Validation

To test TRIM, I filled the Ultra II with sequential 128KB data and proceeded with a 30-minute random 4KB write (QD32) workload to put the drive into steady-state. After that I TRIM'ed the drive by issuing a quick format in Windows and ran HD Tach to produce the graph below.

And TRIM works as it should.

The Introduction, The Drive & The Test AnandTech Storage Bench 2013
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  • maecenas - Tuesday, September 16, 2014 - link

    Interesting stuff, good to see that competition is picking up in this market. I think it will be a significant threshold moment when we see the 240gb SSDs drop below $100. Reply
  • NeatOman - Tuesday, September 16, 2014 - link

    I just saw an OCZ Vertex 460 240GB drive go for $104 the other day on newegg, and of course there sold out. Thats Nucking Futs, since i bought a 120GB 840 pro last year for $140 and the speed looks to be about the same, possibly faster in some ways on the OCZ Reply
  • D. Lister - Sunday, October 12, 2014 - link

    But then, it is OCZ, and many people who know their tech history, wouldn't take an OCZ SSD for free (regardless of whether they are right or wrong in doing so). Reply
  • simonrichter - Friday, October 03, 2014 - link

    I agree, really interesting to see and I'm looking forward to see what the future holds for SSDs. /Simon from http://www.consumertop.com/best-computer-storage-g... Reply
  • CamdogXIII - Tuesday, September 16, 2014 - link

    I bought my first SSD back in 08. 16GB for 80$ Second SSD was 32GB for 100$. Third SSD was 64GB for 100$. Just bought a 256GB 840 Pro for 160$. We have come a long way. Reply
  • PICman - Tuesday, September 16, 2014 - link

    Having an SLC cache is clever. I also like the low power consumption, reasonable performance, and especially the low price. I've had bad luck with the reliability of Samsung products, so it's great that they are getting some competition. Reply
  • Wixman666 - Wednesday, September 17, 2014 - link

    I've had nothing but stellar performance from Samsung SSDs. I have dozens of them out in the field, and not one single failure. Sandisk is OK as well... OCZ might end up OK since Toshiba owns them now. Reply
  • Essence_of_War - Tuesday, September 16, 2014 - link

    I feel like with every new ssd review I read, I grow to appreciate the fantastic value that the MX100 represents even more. Reply
  • frontlinegeek - Saturday, September 20, 2014 - link

    Totally agree. We just outfitted our development PCs at work with MX100 256 GB drives and they are utterly fantastic for price/performance. I cannot at all get over how big an impact an SSD at work makes. FAR more than at home I can say. At least for average home use.

    We run multiple Visual Studio sessions and Oracle SQL Developer along with browsers and other misc apps so the impact has been just terrific.
    Reply
  • fanofanand - Thursday, May 12, 2016 - link

    I know this article is old, but I was researching SSD's and as I trust Anandtech over any other tech site, I came here for the truth. The sad reality is, the MX100 has been overly praised, and is now priced (on Amazon) $72 more than the Sandisk Ultra II at same/similar (512 vs 480) capacity. The MX100 isn't Ultra 2 good...... Reply

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