Abstract: Input data is divided into a plurality of segments, which are processed, in parallel, by respective first processing elements to locate landmarks in the segments. At least one other processing element is used to produce chunks from the input data based on positions of the landmarks provided by the first processing elements.

Abstract: Chunks are stored in a container of a data store, where the chunks are produced by dividing input data as part of a deduplication process. In response to determining that the size of the container has reached a predefined size threshold, at least one of the chunks in the container is moved to another container.

Abstract: A method of limiting redundant storage of data comprises receiving a data stream and partitioning the data stream into a series of data chunks. At least one content hash value for a set of data chunks is generated based on data content of the set of data chunks. One or more data chunks are grouped into a segment with at least one boundary of the segment defined based on an evaluation of content hash values of data chunks. Content hash values of data chunks of the segment are compared to content hash values of data chunks of segments stored on a backup mass storage device. A pointer to a stored data chunk of an existing segment is stored on the backup mass storage device if a content hash value of a data chunk of the segment matches the content hash value of the stored data chunk.

Abstract: A computer-executed method for forming data chunks from a sequence of data values comprises determining whether processing of the sequence of data values has entered a landmark-free region. If processing has entered a landmark-free region, a data chunk is produced using a specialized landmark chunking technique that is specialized for landmark-free regions. Otherwise, the method comprises producing a data chunk using a standard-data landmark chunking technique.

Abstract: A method for backing up data in a plurality of computers connected via a network. The method includes forming partnerships between the plurality of computers such that each computer in a partnership commits under agreements to help backup the data of its partners. The method further includes periodically verifying that previously backed up data is being retained by the computers committed to act as backup partners in accordance with the agreements. In another embodiment, the method provides a distributed cooperative backing up of data in a system that includes a loose confederation of computers connected via a network. In this embodiment the method includes selecting computers as potential backup partners from among the loose confederation of computers connected via the network based on predetermined criteria, and negotiating a reciprocal backup partnership agreement between the computers based on predetermined requirements, including backup requirements.

Abstract: Data processing apparatus comprising: a chunk store containing specimen data chunks, a manifest store containing a plurality of manifests, each of which represents at least a part of a data set and each of which comprises at least one reference to at least one of said specimen data chunks, a sparse chunk index containing information on only some specimen data chunks, the processor being operable to: process input data into input data chunks; identify manifests having at least one reference to one of said specimen data chunks that corresponds to one of said input data chunks and on which there is information contained in the sparse chunk index; and prioritize the identified manifests for subsequent operation.

Abstract: A method for managing access control of a resource includes storing a revocation list containing a list of revoked capabilities and their corresponding groups; storing a group list containing a list of valid groups; receiving a capability revocation request to revoke a specified capability; selecting a revocation method from among a plurality of revocation methods, including an individual capability revocation method and a group revocation method; revoking the specified capability by invalidating the group to which the specified capability belongs if the group revocation method is selected; and revoking the specified capability by invalidating only the specified capability if the individual capability revocation method is selected.

Abstract: A method and an apparatus analyze a computer program for dependencies of the program output on the program input. To analyze the program, the program is transformed by a function into a Boolean expression called a verification condition. An example of this function is the weakest liberal precondition. The verification condition characterizes a condition between the input and the output of the program that must be satisfied for the output to be independent of the input. A theorem prover evaluates the verification condition to determine whether the output would depend on the input if the program was executed. If the verification condition evaluates to true, then the output is independent of the input; false, then the output depends on the input.