Abstract: Non-disruptive migration of the native volume from the source server to the destination server performed by a file switch involves converting the source native volume to a native with metadata volume; converting the native with metadata volume to a mirrored native with metadata volume including the source server and the destination server, the destination server including a mirror copy of the native with metadata volume; removing the source server from the mirrored native with metadata volume; and converting the mirror copy of the native with metadata volume on the destination server to a destination native volume on the destination server.

Abstract: Load sharing clusters in which each node is responsible for one or more non-overlapping subset(s) of the cluster namespace and will process only those requests that access file or directory objects in the partitioned namespace that the node controls while redirecting requests designated for other nodes. A non-overlapping subset may be migrated from a source node to a destination node, for example, for load sharing or hotspot mitigation. Migration typically includes maintaining a file virtualization link from the destination node to the source node to permit forwarding of requests by the destination node to the source node during migration of metadata and then migration of data from the source node. After migration is complete, the file virtualization link is broken and the destination node services requests for the non-overlapping subset from the migrated metadata and data.

Abstract: A method and apparatus for removing duplicated data in a file system utilizing the concept of storage tiers. A synthetic namespace is created via file virtualization, and is comprised of one or more file systems. Deduplication is applied at the namespace level and on all of the file systems comprising the synthetic namespace. All files in a file system in a higher storage tier whose contents are identical to at least one other file in the synthetic namespace are moved to a destination file system in a lower storage tier. For each set of duplicated files that are moved from the original servers, a single instance copy of the file is left behind as a mirror copy. Read access to a duplicated file is redirected to its mirror copy. When the first write to a duplicated file is received, the association from the duplicated file stored in the destination server to its mirror copy that is stored in the origin server is discarded.

Abstract: A method and apparatus for removing duplicated data in a file system utilizing copy-on-write storage tiers. A synthetic namespace is created via file virtualization, and is comprised of one or more file systems. Deduplication is applied at the namespace level and on all of the file systems comprising the synthetic namespace. A set of storage policies selects a set of files from the namespace that become the candidates for deduplication. The entire chosen set is migrated to a Copy-On-Write (COW) storage tier. This Copy-On-Write storage tier may be a virtual storage tier that resides within another physical storage tier (such as tier-1 or tier-2 storage). Each file stored in a Copy-On-Write storage tier is deduped, regardless of whether there is any file with identical contents in the set or in the COW storage tier. After deduplication, the deduped file becomes a sparse file where all the files storage space is reclaimed while all the file's attributes, including size, remain.

Abstract: Inserting a file virtualization appliance into a storage network involves configuring a global namespace of a virtualization appliance to match a global namespace exported by a distributed filesystem (DFS) server and updating the distributed filesystem server to redirect client requests associated with the global namespace to the virtualization appliance. Removing the file virtualization appliance involves sending a global namespace from the virtualization appliance to the distributed filesystem server and configuring the virtualization appliance to not respond to any new client connection requests received by the virtualization appliance.

Abstract: In a switched file system, a file switching device is logically positioned between clients and file servers and communicates with the clients and the file servers using standard network file protocols. The file switching device appears as a server to the client devices and as a client to the file servers. The file switching device aggregates storage from multiple file servers into a global filesystem and presents a global namespace to the client devices. The file switching device typically supports a “native” mode for integrating legacy files into the global namespace and an “extended” mode for actively managing files across one or more file servers. Typically, native-mode files may be accessed directly or indirectly via the file switching device, while extended-mode files may be accessed only through the file switching device. The file switching device may manage file storage using various types of rules, e.g., for managing multiple storage tiers or for applying different types of encoding schemes to files.

Abstract: A plurality of network file manager switches interoperate to provide remote file virtualization. Copies of file data and/or metadata are maintained at a central site and at one or more remote sites. The network file manager switch at the remote site may satisfy certain client requests locally without having to contact the network file manager switch at the central site. A global namespace is maintained and is communicated to all network file manager switches.

Abstract: A switched file system, also termed a file switch, is logically positioned between client computers and file servers in a computer network. The file switch distributes user files among multiple file servers using aggregated file, transaction and directory mechanisms. The file switch distributes and aggregates the client data files in accordance with a predetermined set of aggregation rules. Each rule can be modified independently of the other rules. Different aggregation rules can be used for different types of files, thereby adapting the characteristics of the switched file system to the intended use and to the expected or historical access patterns for different data files.

Abstract: In a switched file system, a file switching device is logically positioned between clients and file servers and communicates with the clients and the file servers using standard network file protocols. The file switching device appears as a server to the client devices and as a client to the file servers. The file switching device aggregates storage from multiple file servers into a global filesystem and presents a global namespace to the client devices. The file switching device typically supports a “native” mode for integrating legacy files into the global namespace and an “extended” mode for actively managing files across one or more file servers. Typically, native-mode files may be accessed directly or indirectly via the file switching device, while extended-mode files may be accessed only through the file switching device. The file switching device may manage file storage using various types of rules, e.g., for managing multiple storage tiers or for applying different types of encoding schemes to files.

Abstract: An apparatus and method are provided in a computer network to decouple client computers from file servers, by placing a transparent network node, also termed a file switch or file switch computer, between the client computers and the file servers. Usage of such a file switch allows reduced latency in file transfers, as well as scalable mirroring, striping, spillover, and other features. The file switch preferably includes at least one processing unit for executing computer programs, at least one port for exchanging information with the file servers and client computers, and a file aggregation module. The file aggregation module includes computer programs for determining a set of file servers from the group of file servers for storing a specified user file, creating a metadata file storing information identifying the set of file servers for storing the user file; and updating directory structures on the set of file servers to indicate storage of the user file.