Abstract: A data storage system includes multiple head nodes and data storage sleds. A control plane of the data storage system designates, for a volume partition, one of the head nodes to function as a primary head node storing a primary replica of the volume partition and designates two or more other head nodes to function as reserve head nodes storing reserve replicas of the volume partition. Additionally, the primary head node causes volume data for the volume partition to be erasure encoded and stored on multiple mass storage devices in different ones of the data storage sleds.

Abstract: Master-slave pairs can be used to provide data redundancy in an electronic data environment. A master peer can include a B-tree with references to the corresponding data. When provisioning a slave, the master can send a point-in-time copy of the B-tree to the slave, which can allocate the necessary space on local storage and update the references of the B-tree to point to the local storage for the slave. If the master and slave become disconnected, one of the peers can function as a solo master until the peers are again connected, at which point the old peer can be brought current or a new slave provisioned. A log peer can also be provisioned by a solo master, which can store data for operations received during the disconnect for use in catching up a slave peer, which could be the old slave, the log peer, or a new peer.

Abstract: The present disclosure provides persistent storage for a master copy using operation numbers. A master copy can include a B-tree with references to corresponding data. When provisioning a slave copy, the master copy sends a point-in-time copy of the B-tree to the slave copy, which stores a copy of the B-tree, allocates the necessary space, and updates the references of the B-tree to point to a local storage before the data is transferred. When writing the data to persistent storage, a snapshot created on the master copy is an operation that is replicated to the slave copy. The snapshot is generated using a volume view that includes changes to chunks of data of the master copy since a previous snapshot, as determined using the operation number for the previous snapshot. Data (and metadata) for the snapshot is written to persistent storage while new I/O operations are processed.

Abstract: Persistent storage for a master copy is provided using operation numbers. A master copy can include a persistent key-value store such as a B-tree with references to corresponding data. When provisioning a slave copy, the master copy sends a point-in-time copy of the B-tree to the slave copy, which stores a copy of the B-tree, allocates the necessary space, and updates the references of the B-tree to point to a local storage before the data is transferred. When writing the data to persistent storage, a snapshot created on the master copy is an operation that is replicated to the slave copy. The snapshot is generated using a volume view that includes changes to chunks of data of the master copy since a previous snapshot, as determined using the operation number for the previous snapshot. Data (and metadata) for the snapshot is written to persistent storage while new input/output operations are processed.

Abstract: A block-based storage system may implement efficient replication for restoring a data volume from a reduced durability state. A storage node that is not replicating write requests for a data volume may determine that replication for the data volume is to be enabled. A peer storage node may be identified that maintains a stale replica of the data volume. One or more replication operations may be performed to update stale data chunks in the stale replica of the data volume with current data chunks without updating data chunks in the stale replica of the data volume that are current. Stale replicas that are no longer needed may be deleted according timeouts or the amount of stale data in the replica.

Abstract: A method for repairing break of a universal connecting rod of a universal coupling includes steps of: cleaning and detecting cracks, providing primary anneal, depositing alloys, providing secondary anneal, manually milling and controlling a quality; wherein depositing the alloys includes forming gradient in an order of a bonding layer, a transition layer, a working layer and a processing layer; wherein the bonding layer: S and P in the depositing area are diluted with an FGM-KM1# material, for removing or reducing the S and P, so as to avoid cold and hot cracks; the transition layer: which is formed by an FGM-KM2# material for improving impact toughness and evacuation stress, and appropriate increasing hardness; the working layer: which is formed by an FGM-KM3# material for improving heat resistance, wear resistance and load capacity; and the processing layer: an FGM-KM4# material is used to reduce surface hardness and improve processing performance.

Abstract: The present disclosure provides persistent storage for a master copy using operation numbers. A master copy can include a B-tree with references to corresponding data. When provisioning a slave copy, the master copy sends a point-in-time copy of the B-tree to the slave copy, which stores a copy of the B-tree, allocates the necessary space, and updates the references of the B-tree to point to a local storage before the data is transferred. When writing the data to persistent storage, a snapshot created on the master copy is an operation that is replicated to the slave copy. The snapshot is generated using a volume view that includes changes to chunks of data of the master copy since a previous snapshot, as determined using the operation number for the previous snapshot. Data (and metadata) for the snapshot is written to persistent storage while new I/O operations are processed.

Abstract: A slave storage is provisioned using metadata of a master B-tree and updates to references (e.g., offsets) pertaining to data operations of the master B-tree. Master-slave pairs can be used to provide data redundancy, and a master copy can include the master B-tree with references to corresponding data. When provisioning a slave copy, the master sends a B-tree copy to the slave, which stores the slave B-tree copy, allocates the necessary space on local storage, and updates respective offsets of the slave B-tree copy to point to the local storage. Data from the master can then be transferred to the slave and stored according to a note and commit process that ensures operational sequence of the data. Operations received to the master during the process can be committed to the slave copy until the slave is consistent with the master and able to take over as master in the event of a failure.

Abstract: A block-based storage system may implement efficient replication for restoring a data volume from a reduced durability state. A storage node that is not replicating write requests for a data volume may determine that replication for the data volume is to be enabled. A peer storage node may be identified that maintains a stale replica of the data volume. One or more replication operations may be performed to update stale data chunks in the stale replica of the data volume with current data chunks without updating data chunks in the stale replica of the data volume that are current. Stale replicas that are no longer needed may be deleted according timeouts or the amount of stale data in the replica.

Abstract: Write optimization for block-based storage performing snapshot operations may be implemented. Write requests for a particular data volume may be received for which a snapshot operation is in progress. A determination may be made as to whether a data chunk of the data volume modified as part of the write request has not yet been stored to a remote snapshot data store as part of the snapshot operation. For a data chunk that is to be modified and that has not yet been stored, the data chunk may be stored in a local in-memory volume snapshot buffer. Once the data chunk is stored in the in-memory volume snapshot buffer, the write request may be performed and acknowledged as complete. The data chunk may be sent to the remote snapshot data store asynchronously with regard to the acknowledgment of the write request.

Abstract: Persistent storage for a master copy is provided using operation numbers. A master copy can include a persistent key-value store such as a B-tree with references to corresponding data. When provisioning a slave copy, the master copy sends a point-in-time copy of the B-tree to the slave copy, which stores a copy of the B-tree, allocates the necessary space, and updates the references of the B-tree to point to a local storage before the data is transferred. When writing the data to persistent storage, a snapshot created on the master copy is an operation that is replicated to the slave copy. The snapshot is generated using a volume view that includes changes to chunks of data of the master copy since a previous snapshot, as determined using the operation number for the previous snapshot. Data (and metadata) for the snapshot is written to persistent storage while new EO operations are processed.

Abstract: A slave storage is provisioned using metadata of a master B-tree and updates to references (e.g., offsets) pertaining to data operations of the master B-tree. Master-slave pairs can be used to provide data redundancy, and a master copy can include the master B-tree with references to corresponding data. When provisioning a slave copy, the master sends a B-tree copy to the slave, which stores the slave B-tree copy, allocates the necessary space on local storage, and updates respective offsets of the slave B-tree copy to point to the local storage. Data from the master can then be transferred to the slave and stored according to a note and commit process that ensures operational sequence of the data. Operations received to the master during the process can be committed to the slave copy until the slave is consistent with the master and able to take over as master in the event of a failure.

Abstract: A block-based storage system may implement efficient replication for restoring a data volume from a reduced durability state. A storage node that is not replicating write requests for a data volume may determine that replication for the data volume is to be enabled. A peer storage node may be identified that maintains a stale replica of the data volume. One or more replication operations may be performed to update stale data chunks in the stale replica of the data volume with current data chunks without updating data chunks in the stale replica of the data volume that are current. Stale replicas that are no longer needed may be deleted according timeouts or the amount of stale data in the replica.

Abstract: A block-based storage system may implement reducing durability state for a data volume. A determination may be made that storage node replicating write requests for a data volume is unavailable. In response, subsequent write requests may be processed according to a reduced durability state for the data volume such that replication for the data volume may be disabled for the storage node. Write requests may then be completed at a fewer number of storage nodes prior to acknowledging the write request as complete. Durability state for the data volume may be increase in various embodiments. A storage node may be identified and replication operations may be performed to synchronize the current data volume at the storage node with a replica of the data volume maintained at the identified storage node.

Abstract: A block-based storage system may implement reducing durability state for a data volume. A determination may be made that storage node replicating write requests for a data volume is unavailable. In response, subsequent write requests may be processed according to a reduced durability state for the data volume such that replication for the data volume may be disabled for the storage node. Write requests may then be completed at a fewer number of storage nodes prior to acknowledging the write request as complete. Durability state for the data volume may be increase in various embodiments. A storage node may be identified and replication operations may be performed to synchronize the current data volume at the storage node with a replica of the data volume maintained at the identified storage node.

Abstract: Write optimization for block-based storage performing snapshot operations may be implemented. Write requests for a particular data volume may be received for which a snapshot operation is in progress. A determination may be made as to whether a data chunk of the data volume modified as part of the write request has not yet been stored to a remote snapshot data store as part of the snapshot operation. For a data chunk that is to be modified and that has not yet been stored, the data chunk may be stored in a local in-memory volume snapshot buffer. Once the data chunk is stored in the in-memory volume snapshot buffer, the write request may be performed and acknowledged as complete. The data chunk may be sent to the remote snapshot data store asynchronously with regard to the acknowledgment of the write request.

Abstract: Methods and systems for cursor remirroring are disclosed. A mirroring process is initiated for a plurality of chunks stored by a master node. The mirroring process comprises visiting a sequence of one or more of the chunks and, for at least some of the chunks, copying chunk data or metadata to a slave node. During the initiated mirroring process, a request is received for a write operation on one of the chunks stored by the master node. If the chunk in the request has been visited in the mirroring process, the write operation is performed on the master node and on the slave node. If the chunk in the request has not been visited, the write operation is performed on the master node and postponed on the slave node until the chunk in the request has been visited in the mirroring process.

Abstract: Write optimization for block-based storage performing snapshot operations may be implemented. Write requests for a particular data volume may be received for which a snapshot operation is in progress. A determination may be made as to whether a data chunk of the data volume modified as part of the write request has not yet been stored to a remote snapshot data store as part of the snapshot operation. For a data chunk that is to be modified and that has not yet been stored, the data chunk may be stored in a local in-memory volume snapshot buffer. Once the data chunk is stored in the in-memory volume snapshot buffer, the write request may be performed and acknowledged as complete. The data chunk may be sent to the remote snapshot data store asynchronously with regard to the acknowledgment of the write request.

Abstract: A method for repairing break of a universal connecting rod of a universal coupling includes steps of: cleaning and detecting cracks, providing primary anneal, depositing alloys, providing secondary anneal, manually milling and controlling a quality; wherein depositing the alloys includes forming gradient in an order of a bonding layer, a transition layer, a working layer and a processing layer; wherein the bonding layer: S and P in the depositing area are diluted with an FGM-KM1# material, for removing or reducing the S and P, so as to avoid cold and hot cracks; the transition layer: which is formed by an FGM-KM2# material for improving impact toughness and evacuation stress, and appropriate increasing hardness; the working layer: which is formed by an FGM-KM3# material for improving heat resistance, wear resistance and load capacity; and the processing layer: an FGM-KM4# material is used to reduce surface hardness and improve processing performance.

Abstract: A block-based storage system may implement reducing durability state for a data volume. A determination may be made that storage node replicating write requests for a data volume is unavailable. In response, subsequent write requests may be processed according to a reduced durability state for the data volume such that replication for the data volume may be disabled for the storage node. Write requests may then be completed at a fewer number of storage nodes prior to acknowledging the write request as complete. Durability state for the data volume may be increase in various embodiments. A storage node may be identified and replication operations may be performed to synchronize the current data volume at the storage node with a replica of the data volume maintained at the identified storage node.