Storage virtualization is the amalgamation of multiple network storage devices into what appears to be a single storage unit. Storage virtualization is usually implemented via software applications and often used in SAN (storage area network), a high-speed subnetwork of shared storage devices, and makes tasks such as archiving, back-up, and recovery easier and faster.
Recommended Reading: Storage Virtualization: Myths, Realities and Other Considerations
A similar phrase, virtualization-aware storage, facilitates management and monitoring of storage in virtualized environments. Learn more about virtualization-aware storage in this Webopedia definition.