The 2U form factor is suitable for many kinds of projects. From virtualization, to specialized appliances, to high-end storage. While 1U servers have certainly become power houses over the past few years, some projects require more expandability.There is no shortage of expansion options with this category of systems. These models allow for 5.25" bays for optical disc drives, CRU bays, and other easy-to-access expansion. While a 2U server can run full-height PCI-express cards in certain configurations, this form factor really shines with low-profile PCI-express cards. Since the low-profile cards are able to fit in the system vertically, you can insert as many cards as the motherboard supports (up to 7 cards total). Storage capacity is great, with some chassis offering up-to 12 full sized hard drives. Thats 120TB of raw storage! This is a good choice as a file server for a medium to large buisness, or as a video surveillance system.