4K Random Read/Write
We preconditioned the SMART Optimus with a heavy 4K random write workload for 18,000 seconds, or five hours. Every second we are receiving reports on several parameters of the workload performance. We then plot this data to illustrate the drives' descent into steady state.
This chart consists of 36,000 data points. The red dots signify the IOPS during the test, and the blue dots are the latency encountered during the test period. We place the latency data in a logarithmic scale to bring it into comparison range. This is a dual-axis chart with the IOPS on the left and the latency on the right. The lines through the data scatter are a moving average during the test. This type of testing presents standard deviation and maximum 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 the scatter testing can give our readers a good feel for the latency distribution by viewing the IOPS at one-second intervals. This should be in mind when viewing our read and write results below.
We provide histograms to provide further latency granularity below. This preconditioning slope of performance happens very few times in the lifetime of the device, and we present these test results only to confirm the attainment of steady state convergence.
Each QD for each 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 SMART Optimus 4K random read speed tops out at 95,250 IOPS at QD256.
The 4k random write speeds top out at 43,936 IOPS at QD256, with very solid consistency. There is very little variability in the write speed results; especially in the high QD range, the I/O stream is remarkably consistent.
The histogram represents the latency of every single I/O during the QD256 testing period represented in percentages. During testing the majority of 4K writes, 73% (9,514,589 I/O's), fell in the 6-8ms range. 24% of requests (3,133,340 I/O's) fell into the 4-6ms range.