A multi-protocol storage appliance serves file and block protocol access to information stored on storage devices in an integrated manner for both network attached storage (NAS) and storage area network (SAN) deployments. A storage operating system of the appliance implements a file system that cooperates with novel virtualization modules to provide a virtualization system that “virtualizes” the storage space provided by the devices. Notably, the file system provides volume management capabilities for use in block-based access to the information stored on the devices. The virtualization system allows the file system to logically organize the information as named file, directory and virtual disk (vdisk) storage objects to thereby provide an integrated NAS and SAN appliance approach to storage by enabling file-based access to the files and directories, while further enabling block-based access to the vdisks.