Abstract: A data storage system employs a virtual disk enclosure that utilizes a number of physical disk drives to create a set of virtual disk drives that are visible to the remainder of the storage system. The virtual disk drives exhibit a set of characteristics such as respective storage capacities, access times, and reliability measures that are user-selectable within respective limits determined by the set of corresponding physical disk drive characteristics. For example, a RAID protection scheme can be used such that the overall storage capacity of the virtual disk drives is less than that of the physical disk drives, but has greater overall reliability/availability. The system may utilize a recursive protection scheme in which the virtual disk drives are utilized according to a second RAID configuration to provide a set of highly available logical storage volumes to host computer systems connected to the data storage system.