VDI solutions built with Dell PowerStore T storage provide flexibility as you scale, reducing the initial and future cost of ownership. Cluster additional controllers and add SSDs and expansion shelves to the storage system to scale horizontally (scaling out). Upgrade controllers using Anytime Upgrade to scale vertically (scaling up).
Scaling out
Each component of the solution architecture scales independently, depending on the required number of supported users. You can add storage controllers, enclosures, and SSDs at any time to expand the storage pool in a modular fashion. The scaling limit for the storage cluster is restricted to four each with three expansion enclosures.
Sizing recommendations change over time as updates are released and qualifications are performed. See the VMware Configuration Maximums website for the latest recommendations.
A Citrix "pod architecture" consists of a virtual apps and desktop "site" and one or more "zones" at each site. The maximum limit when using Citrix pod architecture with the LHC feature enabled is 10,000 VDAs per zone and 40,000 VDAs per site.
A reasonable limit is 5,000 linked clone VMs per zone. Using this limit, 25 compute nodes with 200 Knowledge Worker VMs per node would reach the maximum number of VMs for the zone. This Dell Validated Design for CVAD uses MCS linked clones. The following figure shows a 5,000-user MCS linked clone configuration, which equates to a single zone within a site.
The following figure shows a scale-out of 20,000 MCS linked-clone VMs. The recommended limit for a zone is 10,000 sessions. In this example, there are two sites with three zones each. The sites are load-balanced and presented to the users as a single entity. Each zone contains its own vCenter Server instance and VDI components, as well as a separate PowerStore T storage appliance.
Scaling up
Dell Technologies recommends selecting a PowerStore storage controller that will accommodate your workload as optimally as possible. If future growth or configuration changes require additional performance, the storage controller can be swapped through the Anytime Upgrade program.
For more information about Citrix best practices for scaling, see Citrix VDI Handbook and Best Practices.