Virtual desktop infrastructure introduces unique challenges to storage professionals that aren't as pressing in other types of virtualized environments. The benefits of a virtual desktop infrastructure -- mainly ease of management and access to desktops from anywhere -- are end-user driven. Unfortunately, what's beneficial to end users can often make the task of providing adequate storage more difficult.
Because a single disk image is shared among all desktops, latency is an issue. That makes finding a balance between capacity and performance a struggle for storage administrators. Another potential user benefit of virtual desktop infrastructure (VDI) -- preserving the customizable aspects of individual desktops -- can make storage management more difficult.
Howard Marks, chief scientist at DeepStorage.net, told IT professionals at a recent virtualization seminar that the complexity of VDI storage comes down to whether it is persistent VDI or nonpersistent VDI -- whether a virtual desktop maintains user data or not. Instead of using only one master disk image, persistent VDI uses a separate image for each desktop. So, while it might be more attractive to users, the technology requires more storage capacity.
To limit the storage demand created by persistent VDI, Marks offered several tips:
- Deduplicate full clones. Persistence can be achieved by creating clones of desktops. In many cases, most of the information on those clones will be identical, making it a good opportunity for deduplication to reduce the required capacity to only a fraction of the nondeduplicated clones.
- Local caching. Even in persistent VDI environments, less expensive storage can be used to offset the price of solid-state drives while still providing the performance VDI needs if caching is used for I/O-intensive periods such as boot storms. Marks advised using cache as much as possible.
- Store linked clones on solid-state drives. Linked clones are the images all desktops will work from, so you need to ensure they are stored on higher-performing media.
To hear more of what Marks had to say about storage for persistent and nonpersistent VDI, watch this video of his virtualization seminar.