To provide a comparison with what was considered a leading-edge system for a SQL Server 2008 implementation, we tested a legacy Dell EMC architecture with SQL Server 2008. The goal was to show the performance, scalability, and consolidation improvements that are achievable by moving from a legacy architecture to a modern hyper-converged solution. Key components of the legacy system include:
We matched the configuration and size of the databases and the VMs for the tests of both systems.
The following figure illustrates the distributed workload for the legacy incremental load tests.
Figure 5. Legacy incremental test plan with distributed workload
The test methodology for the legacy system is a two-step load test in which the first step is running a single virtualized database and the second step is running two virtualized databases in parallel. Comparing the legacy SQL Server architecture test metrics with the new Ready Solution test metrics provides insights into the advantages of the new hyper-converged infrastructure.
The legacy system uses a dedicated PowerEdge R720 server and a Compellent SC4020 array to support the workload of a virtualized database. Before the advent of hyper-converged platforms, many IT organizations had dedicated servers for production database workloads. The primary disadvantage of having dedicated servers was the resulting server sprawl that increased both capital expenditure and operating expenses. The advantages of having dedicated servers included:
We used the incremental load‑test methodology on the legacy system to determine system scalability and to create a comparative model against a modern hyper-converged platform. Running one virtualized database on the PowerEdge R720 server produced 1,683 TPS. Running two virtualized databases produced an average of 1,256 TPS, which is a 25 percent drop in performance. Comparatively, the modern hyper-converged infrastructure dropped 1.43 percent in TPS from the first to the second test. Because a 25 percent loss of TPS is significant, we decided to compare a legacy production environment supporting one virtualized database to the hyper-converged platform supporting twelve virtualized databases. The benefits of this comparison include:
Using the findings of one virtualized database on one PowerEdge R720 server, our tests show a peak TPS of 1,683. To simulate the challenge of server sprawl in managing older SQL Server databases, we show that 11 databases servers are required to achieve 18,513 TPS, as illustrated in the following figure.
Figure 6. Simulated legacy SQL Server environment with 11 servers
The Ready Solution for SQL Server with 12 virtualized databases achieves approximately 19,268 TPS. Comparing the legacy to the modern database solution shows that the 11 databases can be migrated to the new platform, providing the capability to retire the legacy servers and reclaim substantial data center space. In this scenario, the organization achieves nearly a 3 to 1 physical consolidation ratio, as illustrated in the following figure.
Figure 7. Consolidating 11 legacy servers to four S2D nodes
The PowerEdge R720 servers have a 2U form factor, and 11 R720 servers would require 22U or 50 percent of a 42U server rack. With the addition of the Compellent SC4020 storage array that is used in the legacy infrastructure, the total rack space is 24U. Comparatively, the PowerEdge R640 servers in the S2D cluster take 1U each, for a total of 4U for all the nodes. Thus, the capability to achieve a near 3 to 1 consolidation ratio of legacy servers to the modern SQL Server solution means a six-times savings in rack space.