This section provides an architecture overview and guidance on managing and scaling a Citrix Virtual Apps and Desktops environment on Dell EMC XC Family devices.
The following figure depicts the architecture of the validated solution, including the network, compute, management, and storage layers.
The deployment option for this Dell EMC Ready System for VDI uses Citrix Machine Creation Services (MCS) with a random or non-persistent desktop—that is, virtual desktops are assigned randomly as users connect. When users log off, changes they made are discarded. The desktop is reset to its original state and is available for another user to log in and use.
Solutions that are based on XC Family devices provide flexibility as you scale, reducing the initial and future cost of ownership. Scale-up flexibility is provided through server hardware upgrade capabilities (for example, addition of storage capacity), while scale-out is enabled through the easy addition of additional XC devices to the XC environment. For XC-based VDI environments, Dell EMC recommends XC640 or XC740xd devices.
Distributed Storage Fabric
The Distributed Storage Fabric (DSF) delivers enterprise data storage as an on-demand service by employing a highly distributed software architecture. Nutanix eliminates the need for traditional SAN and NAS solutions, while delivering a rich set of VM-centric software-defined services. Specifically, the DSF handles the data path of such features as snapshots, clones, high availability, disaster recovery, deduplication, compression, and erasure coding.
The DSF operates via an interconnected network of controller VMs (CVMs) that form a Nutanix cluster. Every node in the cluster has access to data from shared SSD, HDD, and cloud resources. The hypervisors and the DSF communicate using the industry-standard NFS, iSCSI, or SMB3 protocols, depending on the hypervisor in use.
Note: The following example uses a VMware ESXi hypervisor environment. For environments based on other hypervisors (for example, Microsoft Hyper-V, Citrix XenServer, or Nutanix AHV), ensure that you scale pods according to the limits of the hypervisor clusters. Consult your vendor documentation to obtain the cluster-limit information.
Each component of the solution architecture scales independently depending on the required number of supported users. You can add XC devices at any time to expand the Nutanix software defined storage (SDS) pool in a modular fashion.
While there is no scaling limit for the Nutanix architecture itself, VMware recommends that pods be scaled based on the limit of an ESXi cluster, which is 64 nodes.
Another option is to design a large single contiguous NDFS namespace with multiple hypervisor clusters within to provide single-pane management. For example, The following figure shows a large-scale user environment segmented by vSphere HA cluster and broker farm. Each farm compute instance is segmented into an HA cluster with a hot standby node providing N+1. A dedicated pair of management nodes per compute cluster in a separate management HA cluster provides multiple broker farms with separated HA protection while maintaining a single NDFS cluster across all nodes.
Dell EMC recommends a validated disk configuration for general purpose VDI. These configurations leave drive slots available for future vertical expansion and ensure that you protect your investment as new technology transforms your organization.
Citrix VDI Handbook and Best Practicesprovides more information about Citrix best practices and scaling.
Dell EMC recommends that the VDI management infrastructure nodes be separated from the compute resources. Because our test environment was small, both management and compute are in the same vSphere HA cluster. Optionally, the management node can also be used for VDI VMs with an expected reduction of 30 percent of host resources for these nodes only. The 30 percent accounts for management VM resource reservations and should be factored in when sizing.
Compute hosts can be used interchangeably for Virtual Apps and Desktops published apps and desktops.
This design guide describes a single-site or single data center design. For multi-site or disaster recovery (DR) configurations, refer to the following Citrix resource.