Virtual desktop failures can often be traced back to the image file, so it's critical that you keep the golden image pristine. As you build a virtual disk image, pay special attention to the pre-installed applications and OS, security settings, user access and more.
Most virtual desktop infrastructure (VDI) deployments begin with the creation and distribution of a virtual disk image file, which contains the virtual machine (VM), its OS, preferences, applications, settings and so forth. The first step to building a VDI image is determining what kind of image you need.
Software licensing, application security, user rights, platform hardware, data access, user location and infrastructure design can all affect how a VM operates and what services it can run. If any of those elements differ between users, it is almost impossible to build a virtual disk image that multiple users can share. If that's the case, you may need to create a unique image for each user, but that makes VDI harder to deploy and manage than traditional desktops.
Ideally, the image file would be universal golden image, directly usable for each VM and identical across all virtual desktops. As the primary starting image that all others are based off, a gold image is created using the latest licensed OS and is based on the most common elements in the environment. Creating that gold image is arguably the most important step in your VDI deployment because if a golden image is faulty, then every VM created from it will have those problems.
Here are some of the elements you must take into consideration when creating a golden image for VDI.
Operating system. First consider which OS/patch level you will use for the base image. For the majority of implementations, it is probably best to go with what is currently on the physical machines. After all, that will be a stable starting point and reduce the amount of change the end user may experience.
Applications. You also need to decide which applications should be pre-installed. A good starting point is the applications that the majority of end users use most frequently. Apps such as Microsoft Outlook, Office and so forth are a safe bet to include in a base virtual disk image.
Security settings. What security enhancements should be pre-installed? For many, pre-installing the in-house desktop anti-virus and other security applications used as a standard in the enterprise proves to be a wise choice.
Patching and updating. How you will patch and update the golden image? Many administrators choose to manually apply patches and upgrades to make sure the task is done properly. Others rely on automated tools, some of which are included with VDI platforms.
How to provision VMs from a golden image
Customizing the golden image can affect VDI performance
Planning a virtual lab
Default desktop settings. What default settings and policies will be integrated into the golden image? Ideally, you should use the settings that are common to the most users, to standardize the VDI deployment.
Support. What support mechanisms and clients will be pre-installed in the VDI image? Easing support and speeding help desk calls is advantageous for IT staffers. By pre-installing remote support clients, your system will be supported as soon as it goes live.
Virtual machine settings. Look at the application requirements to make sure enough memory, CPU and local storage are available for the virtual machine to perform adequately. Also consider whether the image needs to support and store multimedia data, such as video.
Hardware abstraction. The quickest way to build a virtual disk image is to use a physical machine and then use a physical-to-virtual utility, which abstracts the hardware requirements and creates a virtual machine image. However, the physical machine should be free of any bugs, unneeded applications or obscure settings -- any of which may become resident in the golden image.
Image controls. Will the VDI image be maintained after use or recreated each time a user accesses it? If the virtual machine is assembled each time a user accesses it, the users will get the latest settings and applications, but logins take much longer and they can't personalize desktops. Pre-assembled images load faster and preserve user settings, but those images can take up significant storage space on the network.
Shared vs. dedicated images. Something else to consider is whether individual users only have access to their own images or if they'll share images. Shared images keep storage requirements down but prevent users from personalization. Dedicated images allow users to customize their desktops and install additional applications, but they can quickly consume disk space as more elements are added.
Backup. How will each user's individual virtual disk image be backed up?
Customization. Can users make modifications to their virtual environments?
Disconnected VDI. Consider whether users can run the virtual machine on local hardware to allow for disconnected VDI.
07 Mar 2013