VMware vSphere® 5.5 introduces the beta availability of VMware® Virtual SAN™ (VSAN). This feature allows a new software-defined storage tier, pools compute and direct-attached storage resources, and clusters server disks and flash to create resilient shared storage.
This blog showcases Virtual Desktop Infrastructure (VDI) performance on Virtual SAN using VMware View Planner, which is designed to simulate a large-scale deployment of virtualized desktop systems. This is achieved by generating a workload representative of many user-initiated operations that take place in a typical VDI environment. The results allow us to study the effects on an entire virtualized infrastructure including the storage subsystem. View Planner can be downloaded here.
In this blog, we evaluate the performance of VSAN using View Planner with different VSAN node configurations. In this experiment, we build a 3-node VSAN cluster and a 7-node VSAN cluster to determine the maximum number of VDI virtual machines (VMs) we can run while meeting the quality of service (QoS) criteria set for View Planner. The maximum number of passing VMs is called the VDImark™ for a given system under test. This metric is used for VDI benchmarking and it encapsulates the number of VDI users that can be run on a given system with an application response time less than the set threshold. For response time characterization, View Planner operations are divided into three main groups: (1) Group A for interactive operations, (2) Group B for I/O operations, and (3) Group C for background operations. The score is determined separately for Group A user operations and Group B user operations by calculating the 95th percentile latency of all the operations in a group. The default thresholds are 1.0 second for Group A and 6.0 seconds for Group B. Please refer to the user guide, and the run and reporting guides for more details. Hence, the scoring is based on several factors such as the response time of the operations, compliance of the setup and configurations, and so on.
The host running the desktop VMs has 16 Intel Xeon E5-2690 cores running @ 2.9GHz. The host has 256GB physical RAM, which is more than sufficient to run 100 1GB Windows 7 VMs. For VSAN, each host has two disk groups where each disk group has one PCI-e solid-state drive (SSD) of 200GB and six 300GB 15k RPM SAS disks.
View Planner QoS (VDImark)
The View Planner benchmark was run to find the VDImark for both 3-node and 7-node VSAN clusters and the results are shown in the chart above. In the 3-node cluster, a VDImark of 286 was achieved and for 7-node cluster, a VDImark score of 677 was achieved. So, there is nice scaling in terms of maximum VMs supported as the numbers of nodes were increased in VSAN from 3 to 7.
To further illustrate the Group A and Group B response times, we show the average response time of individual operations for these runs for both Group A and Group B, as follows.
Group A Response Times
As seen in the figure above, the average response times of the most interactive operations are less than one second, which is needed to provide good end-user experience. If we look at the 3-node and 7-node run, we don’t see much variance in the response times, and they almost remain constant when scaling up. This clearly illustrates that, as we scale the number of VMs in larger nodes of a VSAN cluster, the user experience doesn’t degrade and scales nicely.
Group B Response Times
Since Group B is more sensitive to I/O and CPU usage, the above chart for Group B operations is more important to see how we scale. It is evident from the chart that there is not much difference in the response times as the number of VMs were increased from 286 VMs on a 3-node cluster to 677 VMs on a 7-node cluster. Hence, storage-sensitive VDI operations also scale well as we scale the VSAN nodes from 3 to 7.
To see other parts on the VDI/VSAN benchmarking blog series, check the links below:
VDI Benchmarking Using View Planner on VMware Virtual SAN – Part 1
VDI Benchmarking Using View Planner on VMware Virtual SAN – Part 2
VDI Benchmarking Using View Planner on VMware Virtual SAN – Part 3