A performance evaluation of the CVAD offering on IBM Cloud and bare metal server type recommendations based on the results.
The Citrix Virtual Apps and Desktops offering on IBM Cloud offers a streamlined solution for administrators to deploy a CVAD environment in any global IBM data center. The core components are maintained by Citrix, so an administrator can focus on managing their applications and desktops. IBM Cloud handles the provisioning of the Citrix Cloud Connectors and adjacent compute, network and storage and connects the IBM Cloud resource location to the Citrix Cloud.
CVAD for IBM Cloud offering architecture
The CVAD for IBM Cloud architecture is comprised of several virtual machines (VMs) and bare metal servers to enable a full customer-managed virtual desktop resource location. Each resource location is comprised of three cloud connector VMs for communication with the Citrix Cloud — one Linux VM for managing DHCP, one Linux VM to function as a proxy to the internet, one Windows VM for Active Directory Management and a variable number of bare metal servers running Citrix Hypervisor and using shared network-attached file storage.
Citrix Cloud manages the core components and central control layer. Once provisioned, it is the customer’s responsibility to create the resource pools and the master VM image(s) that will run the Citrix Virtual Delivery Agent (VDA) and deliver various applications and desktops to end-users:
Figure 1. Citrix Virtual Apps and Desktops for IBM Cloud architecture diagram.
Performance scalability benchmarking approach
For the performance evaluation, we leveraged LoginVSI — an industry-standard load-testing tool — to evaluate the scalability of the IBM Cloud infrastructure. Over a period of 48 minutes, LoginVSI would launch hundreds or thousands of simulated-user sessions while performance metrics would be collected on the individual session level down to the bare metal host. LoginVSI provides several built-in workloads, three of which we leveraged. Task, Knowledge and Power Workers would simulate varying levels of system load, from light email and Microsoft Office to CPU-heavy Java applications.
LoginVSI would then provide a VSIMax metric, representing how many sessions a system can support before it is saturated. The results of these runs fed into a resource-sizing calculator provided on the main order page for administrators to size and estimate their resource needs. We tested Windows Server 2016 and Windows 10 with November 2020 Microsoft updates and optimized with the Citrix Optimizer tool.
Price-performance results and recommendations for bare metal servers to use for CVAD services
Across all the workloads and processors tested, the primary bottleneck was host CPU utilization. Prior to saturating the host CPUs, roughly 5-9x hosted-shared users per physical core were able to fit on a server, depending on the workload and processor.
Based on these evaluations of different server models, the best overall performance was seen on the platinum series 8260 Cascade Lake, allowing us to reach highs of 8-9x hosted-shared users per physical core. The increased user density can be seen in the price-performance chart below, with the 8260 processor the clear winner for large deployments ranging from several hundred to in the thousands. Additionally, note the inclusion of the silver series 4210 Cascade Lake. Based on a combination of factors —‚ including lower base price, lower user capacity and less physical memory — it can be a favorable option for customers looking to support under 200 users.
Figure 2. Price-per-user per month comparison.
In Table 1, we provide the raw VSImax numbers used for the price-performance calculations in Figure 2.
Table 1. VSI Max and price-per-user breakdown.
Summary of the CVAD on IBM Cloud performance evaluation
This blog post and the white paper serve as overviews of the performance of the Citrix Virtual Apps and Desktops for IBM Cloud offering. Given the price-per-user estimates that customers can achieve, the customer-managed solution provides a flexible, highly performant environment for delivering VDIs on the Cloud.