An Overview of Citrix PVS and Other Provisioning Alternatives

Citrix Provisioning Services (PVS) is used to deploy and manage virtual machine (VM) images in Citrix Virtual Apps and Desktops. PVS streams a master VM image located on a server file-share to either a VM or physical machine in an organization’s on-premises virtual desktop infrastructure (VDI). While Citrix PVS is ideal for physical machines and VMs, its reliance on a network connection means that it can only be used on-premises, unlike another Citrix image management technology, Machine Creation Service (MCS), which can also be used on the public cloud.

What Is Citrix PVS, and How Does It Work?

In a Citrix environment that uses PVS, a boot file is downloaded from the provisioning server when a VM is started. The VM master image is then streamed from the server to the VM’s cache disk, which is also used for write operations while the VM is in use. When the VM is rebooted, the cache disk gets wiped.

When there are changes in the master image, the VMs need to be rebooted. PVS will then stream the new master image to the VMs. This way, your VMs are assured of always running the latest copy of the master image.

Since PVS requires VMs to boot and pull the master image over the network, it is ideal for on-premises virtualization environments. Moreover, with a single master image stored on a virtual disk, organizations don’t have to maintain dozens of disk images, even as they add more machines to their environments.

How Do Citrix PVS and MCS compare?

Citrix PVS is ideal for provisioning standard desktops such as those found in schools and call centers. It’s also best for thin client devices used in accessing virtual desktops.

While PVS can be used in persistent desktops when it’s set to private image mode, this configuration does not provide any benefits to your organization and, thus, is not recommended.

On the other hand, MCS is built to handle VMs on-premises and the public cloud. However, it cannot handle physical machines.

While MCS provides image management, it often acts only as an orchestration engine for the hypervisor or the cloud provider, except in some instances such as when it is used with a hypervisor that cannot reset disks. However, it is often the best provisioning technology to use within your Citrix environment, unless you’re dealing with physical machines.

MCS is ideal for cloud deployments. It can also be used to set up persistent desktops using any of two models: fast clones with small storage footprints and fast create-and-reset times, or full clones with storage migration, backup, and high availability features.

Since MCS comes standard in all editions of Citrix Virtual Apps and Desktops, you can use it within your Citrix environment without any additional licensing costs. The same cannot be said of PVS.

What Are the Licensing Requirements?

Each target device, or machine that will connect to the Citrix PVS Server, requires either a Citrix on-premises or cloud license. Thus, before you can use Citrix PVS within your VDI, you need to enter the number of licenses required for your PVS farms on the Citrix License Server. If you intend to use Citrix PVS across several farms, you need separate Citrix License Servers per farm.

Once the licenses have been set up on the Citrix License Server, run the Citrix PVS Server and connect it to the license server. You also need to specify the license type that has been configured previously on the Citrix License Server.

When setting up additional VMs, you can always add more licenses if there are no more available licenses on the Citrix License Server.

Organizations should upgrade to the most recent version of the Citrix License Server to get the latest PVS features and avoid any potential issues arising from product license grace periods, which fall into two types:

Out-of-box grace period: The Citrix License Server comes with 30-day startup licenses. You should install Citrix PVS Licenses before the 30-day grace period expires to keep the connection between the Citrix License Server and Citrix PVS Servers after 30 days.
License server connectivity-outage grace period: When the out-of-box grace period expires without your organization procuring the required Citrix PVS licenses, connectivity to the Citrix License Server is lost. However, your organization can still use Citrix PVS for provisioning systems for another 30 days.

How Can You Troubleshoot Citrix PVS with Citrix Cloud Director?

You can troubleshoot performance issues such as slow-loading Citrix PVS target devices using Citrix Cloud Director, which provides several important metrics on the VMs in your VDI. Among the metrics tracked by Citrix Cloud Director are:

Network Bandwidth Utilization: The average bandwidth utilization across all network interface cards (NICs).
Server Reconnect Count: The number of times a VM reconnects to the server. This is helpful for resolving issues related to your network, PVS servers and the PVS stream service.
Boot From: Can be a Virtual Disk or Local Disk, or some other boot medium.
Boot Time: The time in seconds it takes to boot up a VM. IT staff may need to check potential issues if there is a significant increase in the boot time.

Ram Cache Usage MB: The Current RAM cache size in MB, which can be useful in setting and optimizing the RAM cache size

Parallels RAS Templates Make Provisioning Simple

Parallels® Remote Application Server (RAS) helps streamline IT infrastructure deployment and maintenance using a set of cloud automation tools, freeing IT administrators from lengthy and repetitive tasks.

Parallels RAS Templates automates the provision of virtual machines (VMs) from either a Remote Desktop Session Host (RDSH) or a VDI host. Using its Test Guest VM Template Wizard, IT administrators can facilitate VM testing and deployment, ensuring that custom-built templates are working smoothly.

Parallels RAS provides an all-inclusive, single license model, eliminating the need to evaluate different licensing models for your needs.

See for yourself how Parallels RAS can help simplify your VDI infrastructure by downloading the trial.

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