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.

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 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.

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.