Abstract: In one embodiment, systems and methods are provided for nonlinear journaling. In one embodiment, groups of data designated for storage in a data storage unit are journaled into persistent storage. In one embodiment, the journal data is recorded nonlinearly. In one embodiment, a linked data structure records data and data descriptors in persistent storage.

Abstract: In one embodiment, systems and methods are provided for nonlinear journaling. In one embodiment, groups of data designated for storage in a data storage unit are journaled into persistent storage. In one embodiment, the journal data is recorded nonlinearly. In one embodiment, a linked data structure records data and data descriptors in persistent storage.

Abstract: In some embodiments, storage devices, such as a storage drive or a storage node, in an array of storage devices may be reintroduced into the array of storage devices after a period of temporary unavailability without fully rebuilding the entire previously unavailable storage device.

Abstract: Systems and methods are provided for passing control of message dependencies and ordering to one or more network nodes participating in a transaction. Thus, messages can be sent to the participating nodes and the participating nodes can handle the messages according to their respective dependencies without first sending a response or waiting for the next message to arrive. In one embodiment, at least one message is flagged with a checkpoint to indicate that messages sent before the checkpoint are to be handled by the participating nodes before messages after the checkpoint. Messages may also be flagged with error-handling information. For example, a message may be marked to indicate that if the message fails, no further messages are to be sent to the node had the failure. Responses to a group of messages can be collected in a single operation.

Abstract: Systems and methods are disclosed that provide an indexing data structure. In one embodiment, the indexing data structure is mirrored index tree where the copies of the nodes of the tree are stored across devices in a distributed system. In one embodiment, nodes that are stored on an offline device are restored, and an offline device that comes back online is merged into the distributed system and given access to the current indexing data structure. In one embodiment, the indexing data structure is traversed to locate and restore nodes that are stored on offline devices of the distributed system.

Abstract: Embodiments of the invention relate generally to incremental computing. Specifically, embodiments of the invention include systems and methods that provide for the concurrent processing of multiple, incremental changes to a data value while at the same time monitoring and/or enforcing threshold values for that data value. For example, a method is provided that implements domain quotas within a data storage system.

Abstract: In one embodiment, systems and methods are provided for nonlinear journaling. In one embodiment, groups of data designated for storage in a data storage unit are journaled into persistent storage. In one embodiment, the journal data is recorded nonlinearly. In one embodiment, a linked data structure records data and data descriptors in persistent storage.

Abstract: Systems and methods are disclosed that provide an indexing data structure. In one embodiment, the indexing data structure is mirrored index tree where the copies of the nodes of the tree are stored across devices in a distributed system. In one embodiment, nodes that are stored on an offline device are restored, and an offline device that comes back online is merged into the distributed system and given access to the current indexing data structure. In one embodiment, the indexing data structure is traversed to locate and restore nodes that are stored on offline devices of the distributed system.

Abstract: In one embodiment, a system for managing semantic locks and semantic lock requests for a resource is provided. Access to the resource is controlled such that compatible lock requests can access the resource and incompatible lock requests are queued.

Abstract: Systems and methods are provided for atomic single-failure non-blocking and double-failure non-blocking commitment protocols. The protocols may be used for a variety of transactions that involve two or more parties including an initiator of the transaction, a coordinator of the transaction, and one or more participants in the transaction. The participants notify the coordinator when they are prepared to commit the transaction. The coordinator then determines when to commit or abort the transaction. If the coordinator disconnects from one or more of the participants, the participants can resolve the transaction independently. Some embodiments also include a distributor that interacts with the coordinator and the participants to resolve the transaction. If one or more parties become disconnected from the coordinator or the distributor, the participants vote to determine whether to receive instructions from the coordinator or the distributor.

Abstract: The systems and methods maintain varying protection levels of related objects, such as when nodes of a data structure are protected at the same or greater protection level as their children nodes. In one embodiment, the nodes store data to track protection levels of their children nodes.

Abstract: In one embodiment, a system and method is provided for reverse lookups using a reverse lookup hint stored in metadata associated with a file or directory. The reverse lookup hint is used to retrieve an entry, comprising a name of the file or directory, which is stored in a map structure related to a parent directory of the file or directory. In an embodiment, the reverse lookup hint comprises a hash value generated from the name of the file or directory.

Abstract: In one embodiment, a user or client device is connected to a distributed file system comprised of one or more physical nodes. The data on each of the physical nodes store metadata about files and directories within the file system. Some of the embodiments permit a user to take a snapshot of data stored on the file system. The snapshot may include a single file, a single directory, a plurality of files within a directory, a plurality of directories, a path on the file system that includes nested files and subdirectories, or more than one path on the file system that each includes nested files and directories. According to one embodiment, the system stores representations of the snapshots that govern a file or directory and its descendants within metadata associated with that file or directory. In one embodiment, before modifying a file or directory, the system updates the representations of the governing snapshots by traversing the metadata of ancestors of the file or directory.

Abstract: Embodiments of the invention relate generally to incremental computing. Specifically, embodiments of the invention include systems and methods that provide for the concurrent processing of multiple, incremental changes to a data value while at the same time monitoring and/or enforcing threshold values for that data value. For example, a method is provided that determines whether multiple incremental changes to a data field could pass a threshold based on keeping track of a possible value range for the data field.

Abstract: In one embodiment, a user or client device is connected to a distributed file system comprised of one or more physical nodes. The data on each of the physical nodes store metadata about files and directories within the file system. Some of the embodiments permit a user to take a snapshot of data stored on the file system. The snapshot may include a single file, a single directory, a plurality of files within a directory, a plurality of directories, a path on the file system that includes nested files and subdirectories, or more than one path on the file system that each includes nested files and directories. In one embodiment, the metadata comprises mini-snapshots for directories representing a path from the root of the file system to the root of the snapshot. The mini-snapshots serve as stand-ins for portions of the file system which are not included in the snapshot, but which permit access to the snapshot data in an intuitive way.

Abstract: In one embodiment, systems and methods are provided for tracking events wherein an event system monitors certain areas of a system. When an event occurs in one area of the system, the event system notifies the processes listening to that area of the system of the event.

Abstract: Embodiments relate to systems and methods for managing stalled storage devices of a storage system. In one embodiment, a method for managing access to storage devices includes determining that a first storage device, which stores a first resource, is stalled and transitioning the first storage device to a stalled state. The method also includes receiving an access request for at least a portion of the first resource while the first storage device is in the stalled state and attempting to provide access to a representation of the portion of the first resource from at least a second storage device that is not in a stalled state. In another embodiment, a method of managing access requests by a thread for a resource stored on a storage device includes initializing a thread access level for an access request by a thread for the resource.

Abstract: Embodiments relate to systems and methods for managing stalled storage devices of a storage system. In one embodiment, a method for managing access to storage devices includes determining that a first storage device, which stores a first resource, is stalled and transitioning the first storage device to a stalled state. The method also includes receiving an access request for at least a portion of the first resource while the first storage device is in the stalled state and attempting to provide access to a representation of the portion of the first resource from at least a second storage device that is not in a stalled state. In another embodiment, a method of managing access requests by a thread for a resource stored on a storage device includes initializing a thread access level for an access request by a thread for the resource.

Abstract: In one embodiment, systems and methods are provided for nonlinear journaling. In one embodiment, groups of data designated for storage in a data storage unit are journaled into persistent storage. In one embodiment, the journal data is recorded nonlinearly. In one embodiment, a linked data structure records data and data descriptors in persistent storage.

Abstract: Embodiments of the disclosure relate generally to file systems. Specifically, certain embodiments include systems and methods for reading objects in a file system. In some embodiments, a first processing thread traverses a portion of a file system and represents file system objects in a data structure. A portion of the data and/or metadata associated with the represented objects may be prefetched to a memory. In some embodiments, a second processing thread consumes the objects represented in the queue. For example, in a file system backup embodiment, the second processing thread may transfer data and/or metadata associated with the objects to an archive target.