Getting around to completing my thoughts from the previous post… 

The Right Desktop Provisioning Method

Once you know whether a group of users need a common desktop image or their own dedicated virtual desktop, you need to make decisions about how to provision that image at the lowest storage and management costs. XenDesktop includes Provisioning Server technologies that enable thousands of virtual desktops to be delivered from a single master image, streamed on demand, in real time. Only the master image needs to be patched and updated – all users will get the benefit the next time they log on. This “pooling” method provides the lowest management costs, fastest provisioning,  and lowest storage requirements – capable of saving up to 90% on storage costs and up to 40% on desktop  maintenance costs. This model is usually suitable for the great majority of users, including productivity workers, as well as some knowledge workers.

The knowledge workers that often make customizations that are not supported by pooled desktops require a different provisioning approach, such as “cloning” – replication of a base master image. Users can install applications and customize as needed – with a tradeoff in higher storage costs. In addition, these desktop clones are more costly to manage than pooled desktops, because each desktop has to be managed as unique entities.  NetApp’s FlexClone, directly integrated with the XenServer console, provides this functionality that helps to simplify the creation of desktops.

The select few power users in an organization can get their blade PC-based virtual desktops via XenDesktop’s provisioning capabilities, however, using a “private” image rather than a standard shared image. This maintains the bare metal performance of the blade PC, while offering the flexibility of being able to move desktops across hardware resources to optimize utilization. Like cloned desktops, this requires storing and maintaining a unique image per user and, therefore, comes at a much higher capital and operational cost than pooled desktops.

Extending Cost Savings with Storage Technologies

Once you know what types of desktops to deliver and how to provision them for best cost advantage, you can then factor in how your storage investments can extend savings and performance. The desktop images, user profiles and end user data can create an avalanche of fast-growing storage. Deduplication technologies can dramatically increase effective primary storage utilization and slow growth by removing identical copies of data within a volume. This process is transparent to the user and typically occurs when the desktop is not in use. The result is up to 35% less storage for user profiles and data.

“Thin provisioning” storage features can also maximize storage utilization and eliminate the guesswork of allocating storage by dynamically assigning capacity as users consume disk space. For pooled desktops, thin provisioning can be leveraged for user data and write back cache. For assigned desktops given to knowledge workers, thin provisioning means no longer having to commit large, mostly empty volumes for user data that may never get fully utilized.

Lastly, the cache on storage controllers can enhance the performance of the Provisioning Server features in XenDesktop, which aids in scalability and thus can help reduce some server infrastructure costs.
Citrix and NetApp have worked together on some lab environments and papers  that you can find here.