Note: this is the first part in a multi-part discussion on PVS and MCS
Since XenDesktop 5 came out, one of the biggest questions flying around is, “Should I use Provisioning Services (PVS) or Machine Creation Services (MCS)?” Both options work and both options provide single image management, but what is the right answer? Is it shocking that this question is the wrong question to ask?
What you should be asking is “What is my desktop virtualization solution going to look like?” Are we only doing Hosted VDI desktops? Do we need Local VMs? Are Hosted Shared Desktops in the mix? (Note: look at the Citrix FlexCast site for a description of each option). Each organization’s desktop transformation roadmap plays an important role in picking the right option. The following diagram was taken from the XenDesktop 5 Reference Architecture, which can be found in the XenDesktop Design Handbook.
One thing you should be able to see is that if you select Machine Creation Services, you can only do the Hosted VDI desktop model on a hypervisor (XenServer, Hyper-V or vSphere) in the data center ONLY. That means no Blade PCs. It means no Hosted Shared Desktops. It means no streamed VHDs. If this is your roadmap, then Machine Creation Services is still a viable option, but the decision cannot be made yet. You still need to look at a few other considerations like SAN requirements, storm impacts, imaging team expertise, etc. before you can make a proper decision, which will be discussed in future blogs.
But what if your design calls for some of these other FlexCast options? Then Provisioning Services will definitely play a major role. However, there still might be a need for a mixed imaging solution based on a few other decision factors. For example, what if you need a desktop where users have complete control of the desktop to install applications or make operating system-level changes that are not captured in profile management tools? I can still do Existing, Physical, Dedicated and Streamed desktops. However, would you use PVS for this (streamed desktops)? It does work, but you probably won’t go with this option. In my experience, using a private desktop model with Provisioning Services is not efficient. It requires complete copies of the base image, configured for private (read/write) mode. You still have to manage these images in a 1:1 fashion (or use an enterprise desktop management tool). You are essentially adding too many layers where other options might be a better fit.
Why not use an Existing, Physical or Dedicated desktop, which relies on either installed images or MCS? If I go with installed images, I need to either install them one-by-one or use cloning solutions like SysPrep. If I use MCS, unique identities are built into the solution. MCS makes the deployment easier than the Existing or Physical desktop model, but they both work. What does this all mean? If you use multiple FlexCast options with private desktops, you will end up using [PVS + (MCS or Installed)]
You don’t want to focus on which technology to use, you want to focus on the overall architecture, which will help guide your decision. But the decision is based on more than the big picture. You need to stay tuned for more on this topic as this isn’t the end yet. We still need to dive deeper into the Hosted VDI Desktop model only scenario to align our business requirements with the appropriate solution.