4K Random Read/Write
We precondition the Toshiba PX02SMF080 for 18,000 seconds, or five hours, receiving reports on several parameters of workload performance every second. We then plot this data to illustrate the drives' descent into steady state.
This chart consists of 36,000 data points. This is a dual-axis chart with the IOPS on the left and the latency on the right. The red dots signify IOPS during the test, and the grey dots are latency measurements during the test period. We place latency data in a logarithmic scale to bring it into comparison range. The lines through the data scatter are the average during the test. This type of testing presents standard deviation and maximum/minimum I/O in a visual manner.
Note that the IOPS and Latency figures are nearly mirror images of each other. This illustrates the point that high-granularity testing can give our readers a good feel for the latency distribution by viewing IOPS at one-second intervals. This should be in mind when viewing our test results below.
We also provide histograms for further latency granularity. This downward slope of performance happens very few times in the lifetime of the device, typically during the first few hours of use, and we present the precondition results only to confirm steady state convergence.
Each QD for every parameter tested includes 300 data points (five minutes of one second reports) to illustrate the degree of performance variability. The line for each QD represents the average speed reported during the five-minute interval.
4K random speed measurements are an important metric when comparing drive performance, as the hardest type of file access for any storage solution to master is small-file random. One of the most sought-after performance specifications, 4K random performance is a heavily marketed figure.
The Toshiba PX02SMF080 produces a blistering average of 124,224 IOPS at QD256, followed by the SMART Optimus with an average of 100,290 IOPS at QD256 in dual port mode. The Optimus has a tighter read pattern with less variability, but with the Toshiba blasting away with 24,000 more IOPS, the variability isn't a concern.
Garbage collection routines are more pronounced in heavy write workloads, leading to more performance variability. The Toshiba PX02SMF080 does not quite reach the beastly random write performance of the SMART Optimus, which averages 44,326 IOPS at QD256. The Toshiba 12Gb/s chugs along with a respectable average of 27,165 IOPS at QD256, but significant performance variability muddies the performance picture. The outlying I/O's that reach down to 15,000 IOPS lower the average speed. Some of this variability might be introduced with the use of dual port functionality. However, the Optimus is tested with the same parameters and does not experience as much variability.
Our write percentage testing illustrates the varying performance of each solution with mixed workloads. The 100% column to the right is a pure write workload of the 4K file size, and 0% represents a pure 4K read workload.
The PX02SMF080 leads the pack with the pure random read workload, but falls into range of the Optimus as we mix in more write activity. The Optimus actually overtakes the PX02SMF080 in the 90% and 100% write categories by leveraging its higher random write performance.
The Toshiba PX02SMF080 provides 2,557,840 I/O's (31.49%) in the 10-20ms range, 1,766,687 I/O's (21.75%) at 6-8ms, 1,544,610 I/O's (19.02%) at 8-10ms, and 1,153,118 I/O's (14.20%) at 2-4ms.
We record the power consumption measurements during our precondition run. We calculate the stated average results during the last five minutes of the test, after the device has settled into steady state.
The Toshiba sports significantly lower power consumption than the Optimus, with an average of 5.63 Watts in comparison to the Optimus' measurement of an average of 7.48 Watts.
IOPS to Watts measurements are generated from data recorded during our precondition run, and the stated average is from the last five minutes of the test. The Toshiba PX02SMF080 averages 4,843 write IOPS per Watt in comparison to the Optimus with 5,906 write IOPS per Watt.