Rebecca Grider, who works at the performance engineering department at VMware posted an article on the VMware VROOM! Blog about performance scaling of an cluster which is build on entry-level hardware. Using VMmark they determined how a four-host cluster with a modest hardware configuration, the Dell PowerEdge R310 running ESX 4.1. would scale under increasing load.
Since most of the times the workload throughput is limited by disk performance the tests were repeated with two different storage arrays, the EMC CX500 and the EMC CX3-20.
The clusters performance was measured under increasing load,starting by running one tile, then increasing the number of tiles until the run failed to meet Quality of Service (QoS) requirements. The tests were conducted using VMmark 2.0, which has the capability to measure the performance of a whole virtual data center and was released earlier this month.
"…As expected, runs using the CX3-20 showed consistently higher normalized scores than those on the CX500. Runs on the CX3-20 outperformed the CX500 by 15%, 14%, and 12% on the one, two, and three-tile runs, respectively. The increased performance of the CX3-20 over the CX500 was accompanied by approximately 10% higher CPU utilization, which indicated that that the faster CX3-20 disks allowed the CPU to stay busier, increasing total throughput.
The results show that our cluster of entry-level servers with a modest disk array supported approximately 220 DVD Store 2.1 operations per second, 16 send-mail actions, and 235 Olio updates per second. A more robust disk array supported 270 DVD Store 2.1 operations per second, 16 send-mail actions, and 235 Olio updates per second with 20% lower latencies on average and a correspondingly slightly higher CPU utilization…"