Abstract: In an aggregated file system, a file may begin with a set of stripe fragments all in the RAID-5 scheme in order to take advantage of the RAID-5 scheme's storage efficiency. After that, when one of the fragments is accessed by a file switch, it will be duplicated into the data mirroring scheme. The file's corresponding metadata server maintains a data structure, e.g., a bitmap, indicating which fragments have been duplicated into the data mirroring scheme. In other words, the file, at this moment, exists in a hybrid scheme. A file consolidator running on the metadata server is triggered at a predefined time to copy the fragments from the data mirroring scheme back to the RAID-5 scheme, This file consolidator also updates the bitmap to reflect the changes to the file's scheme change. This hybrid scheme is expected to increase the I/O capacity of the conventional RAID-5 scheme and the storage usage of the conventional mirroring scheme.

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 ensures consistent and atomic behavior of the switched file system by aggregating in a deterministic way the transactions initiated by the client of multiple independent file switches so that only one of the multiple concurrent transactions attempted on the same aggregated data file may succeed, or so that the transactions are serialized so as to be performed as a sequence of atomic operations. In addition, the integrity of the aggregated data file is safeguarded by issuing locking requests on behalf of certain client applications that do not observe locking mechanism consistently.

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: Client computers are decoupled from file servers in a computer network, by placing a network node, also termed a file switch or file switch computer, between the client computers and the file servers. To the client computers, the file switch appears to be a file server having enormous storage capabilities and high throughput. To the file servers, the file switch appears to be a client as it delegates a single transaction received from a client computer to multiple file servers. The file switch aggregates the file servers' responses to the client computer's request and presents a single response back to the client computer. The file switch performs this transaction aggregation function in a manner that is transparent to both the client computers and the file servers.

Abstract: A file switch, logically positioned between client computers and file servers in a computer network, distributes user files among multiple file servers using an aggregated directory mechanism. A hierarchical directory structure is created on the file servers and used to store metadata files, which store metadata for each user file to indicate where data files, containing portions of the user file, are stored. The file switch automatically spreads the data files and metadata files over a large number of distinct directories on multiple file servers, preventing large number of data files from being stored in a single directory on a single file server. In response to a directory enumeration request from a client computer, one or more directories of metadata files on one or more of the file servers is enumerated, instead of enumerating the data file that store the user file portions.

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.

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 supports caching of a particular aggregated data file either locally in a client computer or in the file switch in accordance with the exclusivity level of an opportunistic lock granted to the entity that requested caching. The opportunistic lock can be obtained either on the individual data files stored in the file servers or on the metadata files that contain the location of each individual data files in the file servers. The opportunistic lock can be broken if another client tries to access the aggregated data file. Opportunistic locks allows client-side caching while preserving data integrity and consistency, hence the performance of the switched file system is increased.

Abstract: An apparatus and method are provided in a computer network to decouple the client from the server, by placing a transparent network node, also termed a file switch or file switch computer, between the client and the server. Usage of such a file switch allows reduced latency in file transfers, as well as scalable mirroring, striping, spillover, and other features.