Which types of storage virtualization are recognized?

Block-level virtualization is recognized as a type of storage virtualization because it abstracts and manages the storage at the block level, making it possible for multiple physical storage devices to be presented as a single block storage unit. This approach allows for enhanced performance and flexibility in managing storage resources, such as allowing for dynamic allocation and resizing of storage based on demand.

Block-level virtualization operates by allowing the virtualization layer to present a unified block storage interface to servers and applications, while behind the scenes, it can manage multiple underlying physical storage devices. This method is crucial for environments that require high performance and low latency, such as databases and enterprise applications.

Other types of storage virtualization exist, such as file-level and application-level virtualization, but they serve different purposes and may not encompass the same breadth of functionality as block-level virtualization, particularly in enterprise storage environments. File-level virtualization manages storage based on files and directories, while application-level virtualization typically refers to the way applications are separated from the operating system and environment, rather than dealing specifically with storage at a low level. Session-level virtualization is related to user sessions and does not pertain to storage virtualization.