11.7 File System and NAS Virtualization

Similar in concept to the virtualization of block-based storage, the virtualization of file systems promises to simplify administration and facilitate sharing of resources. File systems, whether supported on individual file servers or on NAS appliances, become difficult to manage as more file systems proliferate throughout the network.

As shown in Figure 11-9, a virtualized file system configuration relies on software installed on each host. The virtualized file system is the result of merging file system metadata from multiple systems into one extended file system. This design both simplifies administration and enables more efficient use of shared resources such as network-attached storage. As with conventional NAS, NFS and CIFS protocols are used for file access across the LAN, with the further benefit that heterogeneous operating systems can be supported on the same virtualized file system.

Figure 11-9. Virtualized file system based on NAS storage

Virtualization at the file system level can be combined with virtualization of block-level data. The NAS appliances shown in Figure 11-9, for example, could use SAN-attached external storage with interconnection-based virtualization engines to create a storage pool. Administration of both file systems and block data storage would thus be streamlined, reducing the cost of ongoing system management.