How does Storage Spaces work in Hyper-V 3.0?
Storage Spaces (which has also been referred to by Microsoft as "Windows Storage Spaces" or "Storage Spaces and Pools") is a new feature in Windows 8 and Windows Server 2012 that enables thin provisioning of raw storage. The idea is to abstract a storage volume from the physical disk.
The process works like this: An administrator defines a storage pool consisting of physical disks. In doing so, Windows writes pool-specific metadata to each disk in the pool. That way, each physical disk can be uniquely identified within the pool.
Once the storage pool has been created, administrators are free to begin creating virtual hard disks within the pool. These virtual hard disks appear to the operating system as a physical disk even though a virtual hard disk can easily span multiple disks.
Windows Storage Spaces is about far more than just the creation of virtual hard disks. For starters, Windows offers a number of RAID-like features to improve a virtual hard disk's resiliency. For example, a virtual hard disk can be mirrored or striped with parity in order to prevent data loss in the event that a physical disk within the pool fails.
With Windows Storage Spaces' thin provisioning, an administrator can plan for the future without purchasing excessive storage up front. A virtual hard disk's capacity can far exceed the underlying physical disk capacity. Physical disk resources are allocated only as data is added to the virtual hard disk. The nice thing about the storage pool design is that it is possible to add additional physical storage to the pool at any time without impacting the virtual hard disks.
This was first published in October 2012