Whenever I am asked to architect or discuss a virtual desktop infrastructure, I try to ensure that my audience grasps essential design concepts, regardless of the vendor, and the user persona is the No. 1 topic that needs to be understood and discussed.
A user persona is the collection of files and settings unique to an individual user, such as the Windows user profile,
The following five design methods can be used to manage user personas:
1. Local user
This is basically how Windows has dealt with profiles: All user data and profile information is kept locally on the Windows C:\ drive in the Users folder. This method does not allow any flexibility in virtual desktop deployments because many snapshot-based technologies such as VMware View destroy and recreate the C:\ upon refresh of the snapshot. Therefore, local profiles can be a problem.
2. Roaming profiles and folder redirection
For years, Microsoft has told administrators to use this method to handle user profiles. In this configuration, the user profile is synced between a network location and the local desktop. If folder redirection is enabled, then the local copy is also kept on the network file share. This fix can work in a VDI environment, however, roaming profiles have also caused problems and they don't allow for a flexible environment.
3. User data disk (UDD)
VMware has integrated UDD into View to let administrators to move the user persona from the local C:\ to another drive letter. This solution has allowed the linked clones module to function as built.
4. Profile migration, caching and streaming engines
An entire industry has grown up around profile management. The majority of players in this market have developed products that cache a copy of the profile on a central file share and copy or stream it back and forth as needed or scheduled. Vendors include Liquidware Labs (ProfileUnity), RTO Software (recently purchased by VMware for View), RES Software, TriCerat , Immidio and many others.
5. Layered persona
The layering or container concept is the newest design type on the list, and it applies to profile management as well as image management. These tools basically create layers of the operating system, application, patches and personality, and they handle the user profile and data by making each user a container/layer that appears to be on the C:\ but is actually a separate folder. Therefore, the underlying shared OS and applications are never modified by users and can be shared among many users. Companies such as Unidesk and Atlantis do this form of user persona management.
VDI breaks typical local user persona management because a virtual desktop based on the Microsoft, Citrix and VMware model should be flexible and easy to manage. But once a desktop's user profile is on the local C:\, that desktop is tied directly to an end user. As a result, administrators are unable to modify the desktop without affecting the end user. The best way to fix this is to move to a more robust profile management solution. Currently, third parties such as Liquidware, Unidesk, Atlantis, RES Software and many others are doing this much better than the big players.
ABOUT THE AUTHOR
Brad Maltz is CTO of International Computerware, a national consulting firm focused on virtualization and storage technologies. He holds certifications from VMware and EMC for many technologies. Maltz can be reached at firstname.lastname@example.org for any questions, comments or suggestions.
This was first published in September 2010