What is the difference between persistent VDI and non-persistent VDI, and how do they affect storage resources?
Virtual desktops are divided into two types: persistent and stateless. In persistent VDI, the desktops contain the entire configuration and customization performed by the user as the desktop is being used. Storage for persistent desktops is typically a separate logical drive that is mapped to the Documents folder for the user. This means that user data storage is integrated into the desktop virtual machine setup. Clearly, this ties all file performance and data access characteristics to the underlying storage used to provide the virtual machine.
In non-persistent VDI, or stateless VDI, all user configuration and user data is stored on separate hardware that is accessed remotely, for instance, as a network share via CIFS. The stateless approach has a number of advantages. By separating OS from user data, each can be managed separately for capacity, reducing the risk of user data growth affecting all VDI deployments. It also enables both data types to be treated independently from a performance perspective. This provides the opportunity to place user data on lower-cost storage hardware. Finally, the stateless option results in fewer requirements for backup as only the virtual machine master and user data need to be backed up. The recovery of stateless environments is therefore much quicker.
This was first published in June 2012