Windows Server 8 introduces a new approach to storage called Storage Spaces. This is a form of storage virtualisation that makes it easier to scale storage up on demand. There are two components involved. Storage Pools let you aggregate physical disks into a single management unit using any storage subsystem that is available. You can then create virtual disks on those pools. When you create a virtual disk, you specify its resiliency, which can either be none, or mirror, or parity, these options being similar to RAID but according to Microsoft not quite the same. Volumes on virtual disks can be assigned drive letters, or can appear as folders. Storage spaces support thin provisioning. A virtual drive can be bigger than the pool on which it resides. Windows will alert you when the physical free space is running out, and then you can add further drives to the pool.