SanDisk X300s (512GB) Review
by Kristian Vättö on August 21, 2014 2:15 PM ESTPerformance 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.
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The IO consistency is good but obviously not as good as the Extreme Pro due to lower over-provisioning (7% vs 12%). The architecture is still the same, though, as first the performance drops to around 10K IOPS, which is followed by a higher throughput burst. At steady-state the X300s averages about 5K IOPS, which is actually similar to the Crucial MX100 but with added over-provisioning the X300s gets close to the Extreme Pro level.
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Death666Angel - Tuesday, August 26, 2014 - link
I'm totally not getting the new drop down menus in the consistency part of the review. I only get one set of data points in the chart even though I can select 2 (different) items. It changes whether I change the first or second part. Can someone explain what it shows me when?doylecc - Tuesday, August 26, 2014 - link
The drop down menus in the consistency part of the review are not working properly. The only way I could make the charts show the performance of the 25% over-provisioning was to choose another SSD from the menu (I chose the A-Data since it is right next to the X300) then change back to the X300. When I did that the chart would update.I had to repeat with the default over-provisioning menu to get the chart to change back. This is a pain and needs to be corrected!
Kristian Vättö - Wednesday, August 27, 2014 - link
I've noticed that too. Let me see if there is something we can do to fix it -- my HTML skills are limited to copy-pasting so I need to ask someone else to have a look at the code.Gonemad - Wednesday, August 27, 2014 - link
I wonder if encryption would affect deduplication in any kind of setup. As far as I know, repeatable patterns that can be compressed are exactly the thing that encryption prevents, and any deduplication effort must happen before the drive is encrypted. Will encryption ALWAYS be transparent?