The disclosed techniques enable push-based piggybacking of a source-driven logical replication system. Logical replication of a data set (e.g., a snapshot) from a source node to a destination node can be achieved from a source-driven system while preserving the effects of storage efficiency operations (deduplication) applied at the source node. However, if missing data extents are detected at the destination, the destination has an extent pulling problem as the destination may not have knowledge of the physical layout on the source-side and/or mechanisms for requesting extents. The techniques overcome the extent pulling problem in a source-driven replication system by introducing specific protocols for obtaining missing extents within an existing replication environment by piggybacking data pushes from the source.

Push-based piggyback system for source-driven logical replication in a storage environment

Preprocessing kernel print commands

A client system such as a database system may be vulnerable to intrusion by an unauthorized user or system through a reverse secure shell connection that enables the intruder to execute OS-level or shell commands on the client system. A reverse shell connection may be detected by monitoring and inspecting packet data traffic between the client system or internal network, and an exterior or “foreign” network. In one example of such a process, after detecting a normal shell session originating inside the internal network, a reverse shell connection exploiting the initial shell detection is detected by analyzing the transmission directions and payload sizes of a sequence of the monitored packets relative to a predetermined traffic pattern. The specific pattern may be selected for different operating systems.

Reverse shell network intrusion detection

A host divides a dataset into stripes and sends the stripes to respective data chips of a distributed memory buffer system, where the data chips buffer the respective slices. Each data chip can buffer stripes from multiple datasets. Through the use of: (i) error detection methods; (ii) tagging the stripes for identification; and (iii) acknowledgement responses from the data chips, the host keeps track of the status of each slice at the data chips. If errors are detected for a given stripe, the host resends the stripe in the next store cycle, concurrently with stripes for the next dataset. Once all stripes have been received error-free across all the data chips, the host issues a store command which triggers the data chips to move the respective stripes from buffer to memory.

Partial data replay in a distributed memory buffer system

A source application reads a body of data in data block sized units and calculates a checksum value for each data block before sending the data block, the calculated checksum value and the identifier. Upon receipt, a destination application independently calculates a checksum value for each received data block and compares the two checksums. Non-matching checksums indicate a network-induced error in the data block. Identifiers for the erroneous data blocks are transmitted to the source application after all of the data blocks have been initially transmitted. The source application thereafter resends only those data blocks identified. The destination application repeats the process of comparing checksums and transmitting identifiers to the source application until all of the data blocks of the body of data have been correctly received, and then uses the data blocks to recreate the body of data.

Jayalakshmi Pattabiraman

Papers

Application recovery from network-induced data corruption