Abstract: Embodiments of system and method for performing object-modifying commands in an unstructured storage service are described. Embodiments may include utilizing one or more nodes to implement an unstructured storage service including a service interface configured to service data storage requests and data retrieval requests from remote clients. The unstructured storage service is configured to isolate access to each of multiple storage domains of the service to different clients. Embodiments may also include receiving from a given remote client, a request to store a data object to a given storage domain of the service. The request further specifying a command to modify source data for the object prior to storing the object. Embodiments may also include using the unstructured storage service to perform the command without exporting the source data from the unstructured storage service to the given remote client prior to completion of the command.

Abstract: A system and method for maintaining data integrity during data transformation operations. The system and method include obtaining a message from a set of queues, obtaining, from a first data store, a data object indicated by the message, and generating, at a first host, a set of error detection codes corresponding to a transformation of the data object according to a transformation scheme. The system and method further include, transforming, at a second host different from the first host, the data object according to the transformation scheme into the transformation of the data object, verifying the transformation against the set of error detection codes, and storing the transformation in a second data store.

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-level data storage system receives a request to delete a data storage volume. As a result, the data storage volume is deleted and the areas comprising the volume are released and reaped. The areas may contain non-zero data within a plurality of data storage chunks that comprise the areas. An area cleaner is configured to zero out the areas for allocation to a newly created data storage volume.

Abstract: A snapshot depth for a volume is obtained, with the snapshot depth indicating an upper limit to a number of snapshot updates, where an individual snapshot update of the snapshot updates includes data of the volume that has been modified since a time of storage of a previous snapshot update and an amount, based at least in part on the snapshot depth, of other data of the volume. The number of snapshot updates sufficient to construct a full snapshot of a state of the volume at a particular point in time is determined based at least in part on the snapshot depth, and at least the number of snapshot updates is caused to be stored.

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 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: Embodiments of system and method for performing object-modifying commands in an unstructured storage service are described. Embodiments may include utilizing one or more nodes to implement an unstructured storage service including a service interface configured to service data storage requests and data retrieval requests from remote clients. The unstructured storage service is configured to isolate access to each of multiple storage domains of the service to different clients. Embodiments may also include receiving from a given remote client, a request to store a data object to a given storage domain of the service. The request further specifying a command to modify source data for the object prior to storing the object. Embodiments may also include using the unstructured storage service to perform the command without exporting the source data from the unstructured storage service to the given remote client prior to completion of the command.

Abstract: A system and method for using a dead letter queue to regulate host computing systems performing transformation or migration operations. The system and method including reading a message from a queue, the message including one or more references to a set of data objects, with the set of data objects including one or more data objects selected for a transformation operation according to a transformation scheme. The system and method further including performing a mitigation action upon determination that the message is one of a number of unsuccessfully processed messages in the queue that are associated with the computer system, when the number of unsuccessfully processed messages exceed a threshold.

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 snapshot depth for a volume is obtained, with the snapshot depth indicating an upper limit to a number of snapshot updates, where an individual snapshot update of the snapshot updates includes data of the volume that has been modified since a time of storage of a previous snapshot update and an amount, based at least in part on the snapshot depth, of other data of the volume. The number of snapshot updates sufficient to construct a full snapshot of a state of the volume at a particular point in time is determined based at least in part on the snapshot depth, and at least the number of snapshot updates is caused to be stored.

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 system and method for generating and storing at least one snapshot update. The system and method comprising determining a first set of blocks including blocks that have changed since a time of a previous snapshot, determining a second set of blocks based at least in part on a predetermined amount, generating at least one snapshot update of a volume based at least in part on a combination of the first set of blocks and the second set of blocks, and storing the at least one snapshot update.

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: Methods and systems for detecting error in data storage entities based at least in part on importance of data stored in the data storage entities. In an embodiment, multiple verification passes may be performed on a data storage entity comprising one or more data blocks. Each data block may be associated with a probability indicating the likelihood that the data block is to be selected for verification. During each verification pass, a subset of the data blocks may be selected based at least in part on the probabilities associated with the data blocks. The probabilities may be adjusted, for example, at the end of a verification pass, based on importance factors such as usage and verification information associated with the data blocks. The probabilities may be updated to facilitate timely detection of important data blocks. Additionally, error mitigation and/or correction routines may be performed in light of detected errors.

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 block-based storage system may implement dynamic durability adjustment for page cache write logging. A rate of incoming write requests for data volumes maintained at a storage node may be monitored. Based, at least in part, on the rate of incoming write requests, a dynamic modification to a durability property for a data volume may be made, such as enabling page cache write logging the data volume or disabling write logging for the data volume. When incoming write requests are received, a determination may be made as to whether page cache write logging for a particular data volume is enabled. For write requests with disabled page cache write logging, the page cache may be updated and the write request may be acknowledged without storing a log record describing the update in a page cache write log.