There are several different architectures possible when configuring any virtual environment, but especially VDI, with Cisco UCS servers. The first one I'm going to talk about is on-board architecture. This could be used with both rackmount (C Series) and blade (B Series) servers. An on-board architecture simply means that you flash or SSD located directly on the server and you're using it as a sort of cache to increase the performance of your virtual environment.
This is great for VDI especially, because there is a lot of duplicate data being accessed that can be held in the cache on the server. Essentially instead of having to retrieve all the data by going through the LAN and SAN, you can just access the data directly on the physical server. This is a more inexpensive option than buying an all-flash or hybrid array as well. Ideally you would use this for floating pools, rather than persistent desktops.