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Compare Citrix Provisioning Services and Machine Creation Services

One of the most important parts of setting up and managing a XenDesktop deployment is choosing which provisioning tool to use. Citrix provides one streaming option and another that creates VM clones.

Citrix Provisioning Services is the best option for managing enterprise-scale XenDesktop deployments, but Machine Creation Services might be easier for smaller businesses to use because it's simpler to set up.

Between Citrix Provisioning Services (PVS) and Machine Creation Services (MCS), IT has all the tools it needs to configure and deliver virtual desktops to end users. The tricky part is figuring out which one to choose for the task.

Citrix PVS has been around since 2006, when the company acquired the technology from Ardence. MCS came out in 2010 with XenDesktop 5, but Citrix has stated that MCS is not a replacement for PVS; it is another virtual desktop provisioning option for IT.

The basics of Citrix Machine Creation Services

Citrix MCS is a component of XenDesktop that IT can control through the Studio management console. Now that XenApp uses the same FlexCast Management Architecture as XenDesktop in version 7 of those products, companies can now use MCS for XenApp as well. One of the advantages of Citrix MCS is that IT can use it right away, whereas PVS requires administrators to set up an additional infrastructure of Provisioning Servers before they begin virtual desktop production.

MCS is compatible with Citrix XenServer, Microsoft Hyper-V and VMware ESXi hypervisors. It uses the application programing interfaces, or APIs, from those hypervisors to create, configure and control virtual machines (VMs). MCS can create three types of VMs: pooled-random, pooled-static and dedicated.

PVS' streaming technology makes it easier to manage more virtual desktops from a single master image.

The latter becomes a persistent virtual desktop, which includes a Citrix personal vDisk -- a differencing disk that acts as a write cache to store a user's data -- so it will carry over from login to login. Pooled-random desktops are nonpersistent desktops -- meaning they do not save data across VDI sessions -- that are not associated with a specific user. Pooled-static desktops are also nonpersistent, but they are dedicated to specific users. MCS nonpersistent desktops also include differencing disks, but they delete all user-specific data in between VDI sessions.

The first step when using Citrix MCS is to provision a master VM that serves as a template to create clones from. IT can provision the amount of CPU, RAM and disk space included in the VM, and install an operating system and applications. Using the Studio console, admins create a catalog of clone VMs based off the base images. Those VMs live in a data store, which is different from PVS. This setup can take a toll on storage, so it's a good  idea to use thin provisioning, which flexibly delivers only the amount of disk space a user needs, rather than all the allotted disk space for each VM.

IT can also use MCS to update or patch master images and then deploy new VM clones. That capability is useful for nonpersistent desktops, because deleting outdated nonpersistent desktops is no big deal. Persistent desktops can cause trouble for organizations without ample storage, however, because IT has to keep the older version or the user will lose all his data.

In general, MCS uses more IOPS than Provisioning Services. Organizations can mitigate this concern with technologies such as solid-state storage. Additionally, hyper-converged infrastructure, which closely integrates data center hardware and software components, can improve IOPS efficiency and minimize workload concerns.

How to use Citrix Provisioning Services

IT can use Citrix's other configuration tool, Provisioning Services for any version of XenDesktop and XenApp. Citrix PVS is integrated with those two products, but it takes more time to set up because it's not an actual component of XenDesktop. Once IT installs the software and configures the Provisioning Servers, however, PVS' streaming technology makes it easier to manage more virtual desktops from a single master image.

First, IT must install the PVS software onto servers in the data center, and then configure them as a server farm to allow for centralized management. Citrix PVS can stream hundreds or even thousands of desktops from one Provisioning Server, so organizations only need to set up two -- one primary server and one fallback. Additionally, IT has to install the PVS console, configure its master image -- which then lives in a vDisk on or connected to the Provisioning Servers -- and assign that vDisk to the target VMs that will use them. PVS can even stream images to local physical endpoints.

Provisioning Services can stream shared base images to numerous targets at a time, using local storage on the host servers to act as a write cache during read-only XenDesktop sessions. To then deliver virtual desktops to end users, the target VMs stream vDisk images to the endpoints on an as-needed basis. That setup reduces the bandwidth necessary to boot up a VDI session. IT can then use Citrix FlexCast delivery technology to personalize virtual desktops for specific groups of users. Provisioning Services' streaming capability also means that admins only need to update or patch one master image, and the new version streams to the VM the next time it boots up.

IT can use Citrix MCS and PVS for the same VDI deployment, based on which tool is the best fit. The MCS process for production and management might be more familiar to VDI admins, but as a XenDesktop deployment grows and keeping up with maintenance is more of an issue, PVS could be a better fit.

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