The virtual aspect is two fold. First, VRA abstracts multiple controller chipsets from Intel, Broadcom, Marvell, and LSI, whether on the motherboard or an expansion with this Unified RAIDCore Driver. The single driver is the same, regardless, which means the feature sets presented to the system and the user are the same. Because of the virtualization, the management application is the same regardless of chipset, even when there are two separate chipsets in the same server. Unified management seems like small thing until you have to manage multiple systems each with their own management GUI.
More importantly, however, the virtualized driver means that VRA can do some interesting things like spanning RAID volumes across multiple SAS/SATA controller chip sets, which means you are no longer limited to the capacity of a RAID volume based on the number of drives per chip. VRA also supports RAID multiple RAID volumes across multiple SAS and SATA drives.
Other features included support the creation of hidden drives that are used by OEM's as a recovery partition and split and mirror RAID 1n/10n split and mirror configurations. Split mirror is the ability to mirror, in real time, data written from one disk to another for fast back-up and recovery. For example, a server could contain a RAID 1 drive and two mirror drives. One mirror drive is for fast recovery, and the second mirror drive can be removed for off-line storage or given to a developer to work on.
VRA will be supported on Widows and Linux 32 and 64 bit operating systems and Apple's OSX. However, support for hypervisors like Citrix XEN, Microsoft's Hyper-V and VMWare's ESX or vSphere, is not available though Dot Hill says hypervisor support is road mapped. However, since both Linux and Windows are supported by VRA, chances are you might be able to get VRA working on those OS's, but you will be unlikely to get support until they officially offer it for those products.