RDBMS 22 K is a 100 percent random workload – consisting of 60 percent reads and 40 percent writes – that is reflective of real-world relational database data center workloads. Rather than picking a singular application to get results, this test can apply to virtually any application workload that shares a similar workload profile.
The chart below shows that the RDBMS 22 K workload benefits from the increase in available network bandwidth. Peak IOPS for the cluster increased 49 percent from 237 K to 354 K with a 20 percent drop in latency from 2.16 to 1.73 millisecond. However, few environments can run any resource at peak load by choice for a sustained period.
Note: CLM-007409 Disclaimer: Based on internal Dell Technologies testing of a P670N 6 node cluster, running VxRail 8.0.000 with vSAN ESA with 25 GbE and 100 GbE networking. February 2022. Actual results will vary.
The blue 25 GbE line shows that once the workload goes above 190 K IOPS, latency increases sharply from 1.05 to 2.16 millisecond. While this tail of performance does deliver an additional 25 percent of performance or 47 K IOPS, it does come at the price of increased latency. As a best practice, when sizing a cluster for a workload, keep resources at 70 to 80 percent of maximum potential. This best practice allows headroom for unexpected spikes in demand, or a drop in resource availability during planned or unplanned node downtime.
Reviewing the performance at 70 to 80 percent of maximum potential, consider the performance results at these data points:
High performance must be delivered with consistent and predictable latency. The green 100 GbE line shows an almost flat latency line of 0.46 millisecond at 38 K IOPS to 0.75 millisecond at 266 K IOPS, which is in stark contrast to the blue 25 GbE line where a sharp rise in latency is shown.
As mentioned, the only difference between the two test environments was the network configuration. Deploying ESA with 25 GbE networking will only limit the performance potential of an ESA cluster. By using 100 GbE networking, the full potential of ESA can be delivered with high performance and with low, consistent, and predictable latency. If you choose to deploy 25 GbE networking in the future, high performance will be required. Thus, you will need to choose between purchasing additional VxRail nodes or a disruptive upgrade to 100 GbE networking.