Abstract: A primary processor manages metadata of a production dataset and a snapshot copy, while a secondary processor provides concurrent read-write access to the primary dataset. The secondary processor determines when a first write is being made to a data block of the production dataset, and in this case sends a metadata change request to the primary data processor. The primary data processor commits the metadata change to the production dataset and maintains the snapshot copy while the secondary data processor continues to service other read-write requests. The secondary processor logs metadata changes so that the secondary processor may return a “write completed” message before the primary processor commits the metadata change. The primary data processor pre-allocates data storage blocks in such a way that the “write anywhere” method does not result in a gradual degradation in I/O performance.

Abstract: Accordingly a method and interface allows an attribute data base used by an Information Manager to be quickly populated and accurately maintained. A single Bulk Attribute Retrieval Request triggers the primary storage device to collect object attribute information. The method allows for selective collection of objects and attributes by providing filters and attribute lists in the Requests. The Request may be used to provide an incremental scan with appropriate time stamp filtering. In addition, the size of the results can be controlled by the IM by eliminating attributes that are not of interest to the IM. The Request is advantageously issued over a FileMover interface, which is an HTTP connection, and encoded in XML, allowing the IM to easily customize the Request as desired.

Abstract: An intelligent network client has the capability of accessing a first network server in accordance with a first high-level file access protocol, and responding to a redirection reply from the first network server by accessing a second network server in accordance with a second high-level file access protocol. For example, the intelligent network client can be redirected from a CIFS/DFS server to a NFS server, and from an NFSv4 server to a CIFS server. Once redirected, the intelligent network client performs a directory mounting operation so that a subsequent client access to the same directory goes directly to the second network server. For example, the first network server is a namespace server for translating pathnames in a client-server network namespace into pathnames in a NAS network namespace, and the second network server is a file server in the NAS network namespace.

Abstract: A namespace server translates client requests for access to files referenced by pathnames in a client-server namespace into requests for access to files referenced by pathnames in a NAS network namespace. The namespace server also translates between different file access protocols. If a client supports redirection and is requesting access to a file in a file server that supports the client's redirection, then the namespace server may redirect the client to the NAS network pathname of the file. Otherwise, the namespace server forwards a translated client request to the file server, and returns a reply from the file server to the client. A file server may redirect a redirection-capable client's access back to the namespace server for access to a share, directory, or file that is offline for migration, or for a deletion or name change that would require a change in translation information in the namespace server.

Abstract: A file server system has a cluster of server computers that share access to a file system in shared storage. One of the server computers has primary responsibility for management of access to the file system. In order to reduce the possibility of primary server overload when a large number of the clients happen to concurrently access the same file system, most metadata processing operations are offloaded to secondary server computers. This also facilitates recovery from failure of a primary server computer since only a fraction of the ongoing metadata operations of a primary server computer is interrupted by a failure of the primary server computer. For example, a secondary data mover may truncate, delete, create, or rename a file in response to a client request.

Abstract: A namespace server translates client requests for access to files referenced by pathnames in a client-server namespace into requests for access to files referenced by pathnames in a backend NAS network namespace. The namespace server also translates between different file access protocols. The namespace server may change the translation of a client-server network pathname from an old backend NAS network pathname to a new backend NAS network pathname for file migration without disruption to client access during file migration for load balancing or for a more appropriate service level. Client access can also be routed automatically and transparently to replicas in case of server or site failures. The namespace server may create the appearance of a virtual file system that contains multiple physical servers, a virtual share that contains physical shares from different servers, directories that contain files on different servers, and files that contain data from files on different servers.

Abstract: For each high-level protocol, a respective mesh of Transmission Control Protocol (TCP) connections is set up for a cluster of server computers for the forwarding of client requests. Each mesh has a respective pair of TCP connections in opposite directions between each pair of server computers in the cluster. The high-level protocols, for example, include the Network File System (NFS) protocol, and the Common Internet File System (CIFS) protocol. Each mesh can be shared among multiple clients because there is no need for maintenance of separate TCP connection state for each client. The server computers may use Remote Procedure Call (RPC) semantics for the forwarding of the client requests, and prior to the forwarding of a client request, a new unique transaction ID can substituted for an original transaction ID in the client request so that forwarded requests have unique transaction IDs.

Abstract: A protocol is provided for allocating file locking tasks between primary and secondary data mover computers in a network file server. When there is frequent read access and infrequent write access to a file, a primary data mover grants read locks to the entire file to secondary data movers, and the secondary data movers grant read locks to clients requesting read access. When write access to the file is needed, the read locks to the entire file are released and the read locks granted to the clients are released or expire or are demoted to non-conflicting byte range locks managed by the primary data mover. Concurrent read and write access to the same file is then managed by the primary data mover.

Abstract: To permit multiple unsynchronized processors to update the file-modification time attribute of a file during concurrent asynchronous writes to the file, a primary processor having a clock manages access to metadata of the file. A number of secondary processors service client request for access to the file. Each secondary processor has a timer. When the primary processor grants a range lock upon the file to a secondary, it returns its clock time (m). Upon receipt, the secondary starts a local timer (t). When the secondary modifies the file data, it determines a file-modification time that is a function of the clock time and the timer interval, such as a sum (m+t). When the secondary receives an updated file-modification time (mp) from the primary, if mp>m+t, then the secondary updates the clock time (m) to (mp) and resets its local timer.