Abstract: A method is presented for operating a filesystem. The method includes (a) storing data of the filesystem in a data storage filesystem (DSFS) in block-addressable non-volatile storage and (b) storing metadata of the filesystem in a metadata filesystem (MDFS) separate from the DSFS, at least a portion of the metadata being stored in word-addressable memory (WAM) having a persistence feature. Several embodiments are described for achieving this, using, for example, only non-volatile WAM, while other embodiments are described using, for example, a combination of volatile WAM and persistence techniques, while yet other embodiments are described using, for example, a combination of persistence-enhanced WAM and data storage.

Abstract: Read delay or write delay is added to server computers of a geographically distributed data processing system so that when writing to a dataset occurs at a first server and reading from the dataset occurs at a second server, the sum of any delay of returning an acknowledgement of completion of each write request and any delay in the reading of data for each read request is at least the data transmission delay between the two servers. For certain client applications such as NFS, the added delay is sufficient to compensate for the transmission delay without the use of a conventional read lock, which would require a round-trip delay. The method can provide an up-to-date global view of the dataset at each of the servers. The method can also provide equal performance of read access and write access at each of the servers.

Abstract: A request is received, by a storage server, to access a resource based on a filehandle for the resource. A determination is made of whether an entry of a plurality of entries in an exports table has a filehandle that matches the filehandle for the resource. The entry includes a physical path of the resource that is different than an advertised path of the resource, in response to the filehandle in the entry retrieved using the physical path. In response to determining that the filehandle in the entry matches the filehandle for the resource, a determination is made of whether a pathname in the entry matches a pathname for the resource. In response to determining that the pathname in the entry matches the pathname for the resource, a determination is made of whether the client has permission to access the resource. The request to access the resource is executed.

Abstract: A storage system, such as a file server, uses pathname aliasing and exports a stored resource to clients by advertising to the clients a different pathname than the actual pathname of the resource.

Abstract: A system and method integrates a persistent reply cache with operation of a file system executing on a storage system. In an illustrative embodiment, the persistent reply cache is embodied as a file comprising a combination of contents of (i) one or more enhanced non-volatile log records of non-volatile electronic storage, (ii) “dirty” in-core buffer cache data structures, and (iii) on-disk data structures corresponding to those dirty buffer cache data structures. Integration is achieved through atomic operation of the reply cache with the file system to store information associated with a reply, e.g., to a client request, on electronic storage implemented as in-core buffer cache memory of the storage system, as well as on magnetic storage implemented as disks of the system.

Abstract: Apparatus and method are disclosed for managing lock state information in a distributed file system. A set of data containers storing data is maintained. The data containers are striped across a plurality of volumes, where each volume includes one or more data storage devices. A metadata volume is maintained with the plurality of volumes, the metadata volume configured to include a lock state database that stores lock state information for the plurality of volumes. The lock state information is communicated between the metadata volume and the plurality of volumes.

Abstract: A method for managing locking requests for a computer file is disclosed. A plurality of locks is maintained for the file, the plurality of locks having locks of different types. Constraints are tracked on the plurality of locks of different types. A request for a requested lock is received. A determination is made if the requested lock violates any of the constraints on the plurality of locks. The requested lock is granted if there is no violation of any constraint on any of the plurality of locks. The requested lock is denied if the requested lock violates any constraint on any of the plurality of locks. An action disposition set having bit positions which define each lock of the plurality of locks is maintained. Bit-wise logic using the action disposition set determines if a requested lock violates any constraint on any of the plurality of locks.

Abstract: A storage system, such as a file server, uses pathname aliasing and exports a stored resource to clients by advertising to the clients a different pathname than the actual pathname of the resource.

Abstract: A system and method manages lock state information in a storage system. A meta-data volume node includes a lock state database which is a comprehensive source for lock state information about data containers in the system. A plurality of data volume nodes include local lock caches, which contain information about locks. Lock state messaging between the meta-data volume node and the data volume nodes is used to assign locks and to update local lock caches. The meta-data volume node is configured to determine whether input/output requests should be allowed or denied and to instruct the data volume nodes of this input/output operation result. Lock information is also sent to the data volume nodes for storage in local lock state caches to the extent the data volume nodes have the network capacity locally.

Abstract: A system and method to make file handles opaque to other network devices is provided. The system and method encrypts a file handle after it is generated and returns the encrypted file handle to a requesting client. The system and method may also generate a hash table storing hash key, a copy of the encrypted file handle and a copy of the unencrypted file handle. Upon a later receipt of an encrypted file handle, the system and method may hash the encrypted file handle to identify an appropriate hash table entry and it's associated unencrypted hash key. Alternately, the system may decrypt every received encrypted file handle and not utilize a hash table.

Abstract: A system and method manages lock state information in a distributed file system. A meta-data volume includes a lock state database which is a comprehensive source for lock state information about a striped volume set in the system. A plurality of data volumes includes local lock caches which contain information about locks. Lock state messaging between the meta-data volume and the data volumes is used to assign locks and to update local lock caches. The meta-data volume is configured to assigned permissive areas in the data containers accessed by clients in order to efficiently manage the lock state information.

Abstract: A multi-protocol lock manager efficiently manages granting, revoking and releasing of various types of locks on files or regions of files located on a file server, such as a filer. The various locks are associated with multiple different file access protocols, each having its own semantics. The multi-protocol lock manager allows the filer to take appropriate actions with respect to locking requests and other file access operations, while ensuring that the actions taken are always consistent with semantic requirements for each lock, as established by the associated file access protocol.

Abstract: A system and method for mounting and unmounting volumes attached to a data storage system, such as a file server, tracks specific sub-states within each of the overall mounting and unmounting procedure states, in which specific file system requests are and are not allowed (as appropriate) with respect to the mounting/unmounting volume based upon the sub-state. More specifically, for mounting or unmounting, a storage operating system in the file server transitions a volume through a series of sub-states, as tracked in appropriate control structures. Each sub-state is characterized by a set of permitted operations that may be performed while the volume is in that sub-state, entrance and exit criteria for that sub-state, and restricted operations that may not be performed while the volume is that sub-state. During transaction request handling, the storage operating system validates each request against the sub-state to determine the disposition of the request.