Abstract: A method of reading data comprises receiving a request for a stripe of erasure coded data, sending read messages to at least a quorum of storage devices, and receiving at least the quorum of reply messages from the devices. The quorum of the reply messages includes at least a minimum number of stripe blocks needed to decode the data. The quorum meets a quorum condition of a number such that any two selections of the number of the stripe blocks intersect in the minimum number of the stripe blocks. A method of writing data comprises generating a timestamp, encoding the data, sending query messages including the timestamp to the storage devices, receiving query reply messages from each of at least the quorum of the devices, sending write messages to the devices, and receiving a write reply message from each of at least the quorum of the devices.

Abstract: A computer storage system includes a controller and a storage device array. The storage device array may include a first sub-array and a fast storage device sub-array. The first sub-array includes one or more first storage devices storing data. The fast storage device sub-array includes one or more fast storage devices storing a copy of the data stored in the first sub-array.

Abstract: A configuration method includes selecting a design configuration, and modeling the solution configuration having a failure event for the selected solution configuration to determine an amount of down time associated with the failure event. A first penalty cost function is applied the amount of down time to determine a first penalty cost associated with the failure event of the selected solution configuration.

Abstract: The present invention provides techniques for assignment and layout of redundant data in data storage system. In one aspect, the data storage system stores a number M of replicas of the data. Nodes that have sufficient resources available to accommodate a requirement of data to be assigned to the system are identified. When the number of nodes is greater than M, the data is assigned to M randomly selected nodes from among those identified. The data to be assigned may include a group of data segments and when the number of nodes is less than M, the group is divided to form a group of data segments having a reduced requirement. Nodes are then identified that have sufficient resources available to accommodate the reduced requirement. In other aspects, techniques are providing for adding a new storage device node to a data storage system having a plurality of existing storage device nodes and for removing data from a storage device node in such a data storage system.

Abstract: Read, write and recovery operations for replicated data are provided. In one aspect, a system for redundant storage of data included a plurality of storage devices and a communication medium for interconnecting the storage devices. At least two of the storage devices are designated devices for storing a block of data. Each designated device has a version of the data and a first timestamp that is indicative of when the version of data was last updated and a second timestamp that is indicative of any pending update to the block of data. The read, write and recovery operations are performed to the data using the first and second timestamps to coordinate the operations among the designated devices.

Abstract: A method and apparatus is used to divide a storage volume into shards. The division is made using a directed graph having a vertex for each block in the storage volume and directed-edges between pairs of vertices representing a shard of blocks, associating a weight with each directed edge that represents the dissimilarity for the shard of blocks between the corresponding pair of vertices, selecting a maximum number of shards (K) for dividing the storage volume, identifying a minimum aggregate weight associated with a current vertex for a combination of no more than K shards, performing the identification of the minimum aggregate weight for vertices in the directed graph, and picking the smallest aggregated weight associated with the last vertex to determine a sharding that spans the storage volume and provides a minimal dissimilarity among no more than K shards of blocks.

Abstract: Data structure and timestamp management techniques for redundant storage. A plurality of storage devices are interconnected by a communication medium. At least two of the storage devices are designated devices for storing a block of data. Each designated device stores a version of the data and a first timestamp that is indicative of when the version of data was last updated. A second timestamp is indicative of a pending update to the block of data. When the update to the block of data is completed at one of the designated devices, the device discards the second timestamp. A storage device acting as coordinator instructs the device to discard the second timestamp. The designated storage devices store a plurality of blocks of data and corresponding timestamps according to a data structure. At least some of the entries in the data structure correspond to a range of data blocks that share a common timestamp. Entries in the data structure are arranged such that the ranges do not overlap.

Abstract: A technique for emulation of a data storage system. The invention allows the level of services to be provided by a data storage system to be specified in terms of the level of services provided by another storage system. In one aspect, a performance characterization of a data storage device to be emulated is obtained (e.g., by experimental techniques). A specification of a workload is also obtained that includes a specification of a plurality of data stores for the workload. The data stores are assigned to an emulation data storage device according to the performance characterization and according to the specification of the workload such that sufficient resources of the emulation data storage device are allocated to the workload to meet the performance characterization of the data storage device to be emulated. The emulation data storage device is then operated under the workload. Quality-of-service (QoS) control may be performed so as to provide a degree of performance isolation among the workloads.

Abstract: An adjustable storage system modifies a layout of a storage device having a plurality data blocks during a transfer process. The storage system may include an array controller connected to the storage device, and an index table connected to the array controller for storing addresses of data blocks from the magnetic storage device. The addresses of stored data blocks represent the data blocks involved in the transfer process.

Abstract: A computer storage system includes a controller and a storage device array. The storage device array includes a first sub-array and a fast storage device sub-array. The first sub-array includes one or more log-structured storage devices storing data. The fast storage device sub-array includes one or more fast storage devices storing a copy of the data stored in the first sub-array.

Abstract: A method of global data placement. The method includes assigning one or more workloads to one or more compute servers such that each workload flows to one compute server, assigning the data chunks that the workloads accesses to one or more storage servers, and determining how the workloads access the data.

Abstract: A computer storage system includes a controller, a first storage device and a second storage device including at least one fast storage device. The controller is configured to perform data operations. The first storage device stores data, and the second storage device stores data redundant to the data stored in the first storage device.

Abstract: A computer storage system includes a controller and a storage device array. The storage device array may include a first sub-array and a fast storage device sub-array. The first sub-array includes one or more first storage devices storing data. The fast storage device sub-array includes one or more fast storage devices storing a copy of the data stored in the first sub-array.

Abstract: A method and apparatus is provided for measuring and optimizing the orientation of data access of an electronic storage device according to data access characteristics. Monitoring storage access activity in an area of storage space is performed to gather data pertaining to one or more storage access characteristics. Measuring is performed of the characteristics of the storage access activity of at least two individual portions of the storage space. The portions are then combined in a manner to more judiciously utilize storage space. Depending on their homogeneity of access characteristics, the individual portions may then be left alone, merged with other similar portions, or further subdivided into sub-portions, which may be further merged, divided or left alone. At each merger or division determinations can then be made of whether the characteristics of storage access activity of one individual portion or sub-portion are similar to that of another portion according to predetermined criteria.

Abstract: Data storage devices of an enterprise system are tested to determine whether the enterprise system is optimally configured. Each data storage device is tested to determine whether it can satisfy a performance requirement for an assigned group of n workloads. A group of n inequalities are generated, and only up to n of the inequalities may be evaluated to determine whether the device satisfies the performance requirement for the assigned group of workloads. The inequalities are based on a phased, correlated model of I/O activity.

Abstract: A method and apparatus is provided for measuring and optimizing the orientation of data access of an electronic storage device according to data access characteristics. Monitoring storage access activity in an area of storage space is performed to gather data pertaining to one or more storage access characteristics. Measuring is performed of the characteristics of the storage access activity of at least two individual portions of the storage space. The portions are then combined in a manner to more judiciously utilize storage space. Depending on their homogeneity of access characteristics, the individual portions may then be left alone, merged with other similar portions, or further subdivided into sub-portions, which may be further merged, divided or left alone. At each merger or division determinations can then be made of whether the characteristics of storage access activity of one individual portion or sub-portion are similar to that of another portion according to predetermined criteria.

Abstract: An apparatus for and a method of non-linear constraint optimization in a storage system configuration. In accordance with the primary aspect of the present invention, the objective function for a storage system is determined, the workload units are selected and their standards are determined, and the storage devices are selected and their characteristics are determined. These selections and determinations are then used by a constraint based solver through non-linear constraint integer optimization to generate an assignment plan for the workload units to the storage devices.

Abstract: Given a multi-component system and a multi-part performability requirement, a method and apparatus for determining whether the system will satisfy the multi-part performability requirement is described. The method uses a failure-scenario generator that analyzes the most-likely failure scenarios first and operates only until a PASS-FAIL determination can be rendered.

Abstract: A method predicts performance of a system that includes a plurality of interconnected components defining at least one data flow path. The method references a workload specification for the system. The method models the system using one or more component models. Each component model represents selected one or more of the components. Each component model is arranged in like relationship to the data flow path as the selected one or more of the components represented by the component model. Each component model is (a) a constraint upon the workload specification input to that component model or (b) a transformer of the workload specification input to that component model so as to result in one or more output workload specifications that are input workload specifications to subsequent component models along the data flow path or (c) both a constraint and a transformer. At least one of the component models is a constraint.

Abstract: A high-level language description of a data storage system is generated and translated, directly or indirectly, into specific configuration commands.