Example data storage systems and methods are described. In one implementation, a method identifies data to be written to a shared storage system that includes multiple storage nodes. The method communicates a write operation vote request to each of the multiple storage nodes. The write operation vote request is associated with a data write operation to write the identified data to the shared storage system. A positive response is received from at least a portion of the multiple storage nodes. The data write operation is initiated in response to receiving positive responses from a quorum of the storage nodes.

Embodiments herein are directed to efficient crash recovery of persistent metadata managed by a volume layer of a storage input/output (I/O) stack executing on one or more nodes of a cluster. Volume metadata managed by the volume layer is organized as a multi-level dense tree, wherein each level of the dense tree includes volume metadata entries for storing the volume metadata. When a level of the dense tree is full, the volume metadata entries of the level are merged with the next lower level of the dense tree. During a merge operation, two sets of generation IDs may be used in accordance with a double buffer arrangement: a first generation ID for the append buffer that is full (i.e., a merge staging buffer) and a second, incremented generation ID for the append buffer that accepts new volume metadata entries. Upon completion of the merge operation, the lower level (e.g., level 1) to which the merge is directed is assigned the generation ID of the merge staging buffer.

A distributed storage integrity system in a dispersed storage network includes a scanning agent and a control unit. The scanning agent identifies an encoded data slice that requires rebuilding, wherein the encoded data slice is one of a plurality of encoded data slices generated from a data segment using an error encoding dispersal function. The control unit retrieves at least a number T of encoded data slices needed to reconstruct the data segment based on the error encoding dispersal function. The control unit is operable to reconstruct the data segment from at least the number T of the encoded data slices and generate a rebuilt encoded data slice from the reconstructed data segment. The scanning agent is located in a storage unit and the control unit is located in the storage unit or in a storage integrity processing unit, a dispersed storage processing unit or a dispersed storage managing unit.

A distributed storage integrity system in a dispersed storage network includes a scanning agent and a control unit. The scanning agent identifies an encoded data slice that requires rebuilding, wherein the encoded data slice is one of a plurality of encoded data slices generated from a data segment using an error encoding dispersal function. The control unit retrieves at least a number T of encoded data slices needed to reconstruct the data segment based on the error encoding dispersal function. The control unit is operable to reconstruct the data segment from at least the number T of the encoded data slices and generate a rebuilt encoded data slice from the reconstructed data segment. The scanning agent is located in a storage unit and the control unit is located in the storage unit or in a storage integrity processing unit, a dispersed storage processing unit or a dispersed storage managing unit.

There is provided a distributed object storage system that includes several performance optimizations with respect to efficiently storing data objects when coping with a desired concurrent failure tolerance of concurrent failures of storage elements which is greater than two and with respect to optimizing encoding/decoding overhead and the number of input and output operations at the level of the storage elements.

A storage system according to the present invention includes: a block detecting means for checking whether respective block data obtained by division are already stored in a storage device; and a data writing means for storing the respective block data obtained by division with duplicated storage eliminated into the storage device. The block detecting means detects a share rate representing a rate of a shared portion between a plurality of consecutive block data configuring a predetermined range in write target data among the block data obtained by division and a plurality of block data in a predetermined range already stored consecutively in the storage device. The data writing means, depending on the detected share rate, newly stores the block data obtained by division, into the storage device.

A storage network operates by: encoding a data segment into a set of encoded data slices, wherein a read threshold of encoded data slices of the set of encoded data slices is required to decode the data segment, wherein the read threshold has a value greater than one, and wherein the data segment has an associated security level; selecting a subset of the plurality of storage units based on the security level, wherein the subset includes at least the read threshold of storage units of the plurality of storage units, wherein each of the subset of the plurality of storage units has a connection security approach that corresponds to the security level; and communicating the set of encoded data slices to the subset of the plurality of storage units in accordance with the connection security approach associated with each of the subset of the plurality of storage units.

A distributed storage integrity system in a dispersed storage network includes a scanning agent and a control unit. The scanning agent identifies an encoded data slice that requires rebuilding, wherein the encoded data slice is one of a plurality of encoded data slices generated from a data segment using an error encoding dispersal function. The control unit retrieves at least a number T of encoded data slices needed to reconstruct the data segment based on the error encoding dispersal function. The control unit is operable to reconstruct the data segment from at least the number T of the encoded data slices and generate a rebuilt encoded data slice from the reconstructed data segment. The scanning agent is located in a storage unit and the control unit is located in the storage unit or in a storage integrity processing unit, a dispersed storage processing unit or a dispersed storage managing unit.

There is provided a distributed object storage system that includes several performance optimizations with respect to efficiently storing data objects when coping with a desired concurrent failure tolerance of concurrent failures of storage elements which is greater than two and with respect to optimizing encoding/decoding overhead and the number of input and output operations at the level of the storage elements.

In a Distributed Virtual Array data storage system, a storage pool receives, from at least one writing entity within a host, a request to write a container of data that is identified by a unique key that is independent of physical storage identifiers and that comprises a set of data chunks. The key indicates a plurality of storage devices in which to store the data chunks, which are accordingly stored in those storage devices. Different combinations, each comprising a layout map, of storage devices are represented in a layout table. Information in the container key is used to select which layout map to use for the chunks of each container. An error-correction chunk is preferably also stored along with the chunks of each container so as to enable data container reconstruction in case of storage device failure.