While working on a XenDesktop project in a huge VMware shop, I started thinking if a single hypervisor should be used or if multiple hypervisors should be used in XenDesktop deployments. Then I was on a conference call with Scott Lane, Senior Systems Engineer for Citrix in the Great Plains Area and also a co-author on this post, about the same XenDesktop project and we started discussing thoughts on this. A number of factors came to mind like cost of the hypervisor (VMware licenses for the XenDesktop project are adding a nice chunk of change to the cost of the deployment), hypervisor features, etc. In this blog post I am going to talk about things to consider about different hypervisors for XenDesktop deployments.
I often go into shops that already have large VMware infrastructures deployed and talk about XenDesktop. When I’m talking to the customer or potential customer about XenDesktop I always mention that with XenDesktop VDI, Enterprise, or Platinum Editions they will also get XenServer Enterprise Edition. This always gets mixed results. Most think I’m trying to push VMware out the door when I talk about XenServer. This is not the case at all. When I talk about XenServer I am focused on the XenDesktop environment and nothing else in their environment. I tell the customer that you may want to look at XenServer for the provisioned XenDesktop virtual Windows desktops and XenApp servers and then use their existing VMware infrastructure for the XenDesktop infrastructure components. Use XenServer that is included with XenDesktop for your XenDesktop Windows desktop and XenApp server infrastructure and continue to use your VMware infrastructure for everything else.
I also talk about the open architecture of XenDesktop and that they can choose between Citrix XenServer, Microsoft Hyper-V, and VMware vSphere hypervisors for the XenDesktop virtual desktops. I talk about Hyper-V as another option and the benefits of using Hyper-V for the hypervisor in XenDesktop deployments especially when the customer is talking about deploying Windows 7 and Windows 2008 virtual machines in their XenDesktop infrastructure. Some think that having multiple hypervisors is too much to manage or there is a big learning curve. Most customers I have worked with that are strong in virtualization find XenServer pretty easy to learn. With tools like System Center Virtual Machine Manager that can manage ESX/vSphere and Hyper-V from a single console make management of multiple hypervisors easy for multiple hypervisor deployments. When System Center Virtual Machine Manager supports management of XenServer, all three hypervisors will be managed from a single console.
XenDesktop deployments on Citrix XenServer considerations:
- Included with XenDesktop, no extra cost for the hypervisor
- XenServer redundancy built-in (no management server to deploy)
- XenCenter is easy to use for both server virtualization and desktop administrators
- Single vendor to call for technical support
- XenServer 5.6 features has made XenServer a more complete product
- Dynamic Memory Control
- Enhanced CPU compatibility for XenMotion
- Enhanced snapshots, including full system state and one-click revert
- Automation for Workload Balancing
- Administrative Delegation, Logging and Audit Reports
- XenServer virtual machine tools have to be installed and maintained
- XenServer can direct boot VHD files to update XenServer tools and Provisioning Services tools
- New option in XenServer 5.6 to select network boot when building virtual machine template
- XenServer has built-in optimizations for XenApp
- Citrix Virtual Appliances are released on XenServer first
- Having XenServer already in place makes you already prepared for Multi-GPU Passthrough for HDX 3D Pro Graphics and Distributed Virtual Switching (DVS) that are coming in tech preview/private beta soon.
XenDesktop deployments on Microsoft Hyper-V R2 considerations:
- System Center Virtual Machine Manager is needed to manage hosted virtual desktops
- Server and Desktop administrators who already use System Center products will already be familiar with the look and feel of System Center Virtual Machine Manager console
- System Center Essentials 2010 could be used for smaller XenDesktop deployments (for XenDesktop deployments under 500 seats when supported)
- Management server (System Center Virtual Machine Manager or Essentials 2010) can be single point of failure for management of hosted virtual desktops
- Microsoft Hyper-V Server 2008 R2 Edition is free with features like Live Migration, Host Clustering, etc but needs System Center Virtual Machine Manager or Essentials 2010 to manage hosted virtual desktops
- System Center Virtual Machine Manager or Essentials 2010 console needs to be installed on XenDesktop Delivery Controllers and Provisioning Servers for management and for use with XenDesktop Setup Wizard
- Windows 7 virtual desktops and XenApp servers running on Windows 2008 have integration components built-in to the operating system. No need for 3rd party virtual machine tools to install and maintain.
- Hyper-V can direct boot VHD files to update Provisioning Services tools
- Legacy NIC needed for network boot/Provisioning Services and Synthetic NIC for all other traffic
- Network boot enabled in virtual machine settings
- Windows 7 and Windows 2008 on Hyper-V are better together
- Citrix and Microsoft relationship
- Citrix Knowledge Center Article CTX124687 – XenDesktop with Microsoft Hyper-V Design Guide
- The Citrix Blogs – Seven Things I Learned Testing XenDesktop with Hyper-V
- Citrix Essentials for Hyper-V for site recovery/disaster recovery
- System Center Virtual Machine Manager for mixed vSphere and Hyper-V deployments with XenServer support coming in the future for a possibly mixed environment of all 3 hypervisors
- Having Hyper-V already in place makes you already prepared for RemoteFX and Dynamic Memory that are coming in service pack 1
XenDesktop deployments on VMware vSphere considerations:
- Added cost of VMware infrastructure
- Has per processor/core licensing (systems that have processors with over 6 cores need Advanced or Enterprise Plus licenses)
- vSphere/vCenter server is needed to manage virtual desktops
- Management server (vSphere/vCenter) can be single point of failure for management of hosted virtual desktops
- VMware ESXi is free but needs vSphere/vCenter server/agents to manage hosted virtual desktops
- vSphere/vCenter has to be setup to allow HTTP access, default SSL certificate imported (VI 3.5), or SSL certificate needed (vSphere 4) for XenDesktop Delivery Controller access/management and for use with the XenDesktop Setup Wizard
- VMware integration issues with Provisioning Services Target Devices – VMXNet3 driver issues with Windows Vista, 7, and 2008
- VMware integration issues with XenDesktop Virtual Desktop Agent – Video driver issues with Windows Vista and Windows 7
- Citrix Knowledge Center Article CTX124877 – Unable to Connect to XenDesktop Virtual Desktop Agent on Vista or Windows 7 with WDDM Driver
- Citrix Knowledge Center Article CTX123952 – Unable to Connect to XenDesktop Virtual Desktop Agent on Windows 7 with VMware Tools ESX 4.0 Update 1 – also had to do this when installing XenDesktop Virtual Desktop Agent on Windows 7 or install would fail
- VMware virtual machine tools have to be installed and maintained
- VMware virtual machine has to be reversed imaged to update virtual machine tools or Provisioning Services tools – Hyper-V or XenServer instance in VMware environment could also do this
- Network boot enabled in virtual machine BIOS by editing virtual machine properties to enter BIOS on next boot
- Need at least a 1MB disk attached or Target Device will BSOD
- Most matured hypervisor with largest data center footprint
So as you can see a number of factors come into play when choosing a hypervisor for your XenDesktop infrastructure. Some customers I have worked with have stayed with their current hypervisor and kept a single hypervisor infrastructure all on VMware vSphere. While other customers I have worked with have gone with multiple hypervisor infrastructures having the XenDesktop infrastructure components on VMware vSphere and the virtual desktops on Citrix XenServer. I have even had one customer put everything relating to Citrix on Citrix XenServer and kept the rest of their infrastructure on VMware vSphere. I will be doing an install next month in a pure XenServer environment (They have been running Xen since long before the Citrix acquisition). The demo lab at my office and what we use for workshops is a mix of Citrix XenServer for the virtual appliances and Microsoft Hyper-V R2 for everything else. Microsoft Hyper-V R2 is getting more consideration and interest lately and I expect to start doing more and more XenDesktop deployments on Hyper-V soon.
For XenDesktop deployments do you stick with a single or have multiple hypervisors? Every environment is different and everyone has their own take on this. With the way the economy has been customers are looking at other options instead of paying a premium for what they currently have. Especially since cost for and deployment of a XenDesktop infrastructure are a huge factors these days. Citrix XenServer and Microsoft Hyper-V R2 are getting more and more interest and gaining ground every day as the feature sets become more and more comparable with VMware vSphere. With XenDesktop having an open architecture you have options when it comes to the hypervisor. The hypervisor is becoming a commodity anyway, right?