Systems and methods are disclosed, including rebuilding a logical-to-physical (L2P) data structure of a storage system subsequent to relocating assigned marginal group of memory cells of a memory array of the storage system, such as when resuming operation from a low-power state, including an asynchronous power loss (APL).

A computer system installed on board a carrier, communicating in a network with a data concentrator and with a monitor, and implementing at least one service that is critical for the operating safety of the carrier, the critical service being redundant in at least two instances (δ.sub.1, . . . δ.sub.m) on different respective computers (C.sub.1, . . . , C.sub.m) connected to the network, each computer (C.sub.k) implementing at least one software task implementing an instance (δ.sub.k) of the critical service being configured to implement the critical service by way of time control.

An illustrative unified data storage method includes providing, by a data storage system, block containers that represent a linear address space of blocks; and using, by the data storage system, the block containers to store content for a plurality of different data storage services. In certain examples, the different data storage services include at least one of a file storage service, an object storage service, or a database service.

In one example method, a second memory stores data in a database, and the second memory is a memory independent of a first device and a second device. When determining that a database service needs to be switched, the first device may migrate a redo log of the database from a first memory of the first device to the second memory. The second device migrates the redo log from the second memory to a third memory of the second device, and the first device and the second device perform operating system status migration online.

This application provides a data recovery method and apparatus, and relates to the field of computer technologies. The method includes: determining first data, where the first data is application data generated when an application program runs normally; storing the first data in a handle record, where the handle record is managed by using a reference count mechanism; and when the application program is unexpectedly restarted, obtaining the handle record, and restoring the application program, based on the handle record, to a status before the application program is unexpectedly restarted.

With the method for snapshotting metadata, in response to reaching a current snapshot moment, a second basic version number of a binary search tree in a database at the current snapshot moment is generated according to a first basic version number at a previous snapshot moment; during a process from the current snapshot moment to a next snapshot moment, whenever metadata in the database is updated, the binary search tree is updated according to the updated metadata, and an updated version number of the binary search tree after each update is generated according to the second basic version number; and in response to reaching the next snapshot moment, a snapshot operation is performed on binary search trees corresponding to all version numbers generated between the current snapshot moment and the next snapshot moment to generate snapshot information of the current snapshot moment.

The disclosure herein describes enhancing data durability of a base component of a data object using an unplanned delta component during transient fault unavailability. A base component of a data object becoming unavailable due to a transient fault is detected. A delta component associated with the base component is generated, wherein the delta component includes unwritten storage space with an address space and a tracking bitmap including a plurality of bits associated with data blocks of the address space of the delta component. The stale LSN with which the base component is associated is assigned to the delta component and the delta component is synchronized with an active component of the data object based on the assigned stale LSN. The delta component records write I/O targeted for the base component and, based on detecting the base component becoming available, the base component is synchronized with the delta component.

One example method includes performing failure recovery operations in a computing system using matrix clocks. Each node or process in a computing system is associated with a matrix clock. As events and transitions occur in the computing systems, the matrix clocks are updated. The matrix clocks provide a chronological and casual view of the computing system and allow a recovery line to be determined in the event of system failure.

The embodiments described herein describe technologies for non-volatile memory persistence in a multi-tiered memory system including two or more memory technologies for volatile memory and non-volatile memory.

Techniques are disclosed herein for identifying, recording and restoring the state of a database session and various aspects thereof. A session template data structure is generated that includes session attribute values describing various aspects of the session that is established between a client system and a database management system (DBMS and enables the client system to issue to the DBMS commands for execution. Based on the session attribute values, DBMS may generate a template identifier corresponding to the session template data structure. The template identifier may be stored in an association with the session state that it partially (or in whole) represents. In an embodiment, when another state of a session is captured, if the template identifier for the state is the same, then rather than storing the attribute-value pairs for the other state, the template identifier is further associated with the other state. In an embodiment, a request boundary is detected where the session is known to be at a recoverable point. If recovery of the session is needed, the session state is restored, and replay of commands start from this point. Each command replayed is verified to produce the same session state as it produced at original execution. If the session is determined to be a safe point, then all the commands recorded for replay prior to the safe point may be deleted. In an embodiment, the template is used to set the initial state when borrowing from a session pool The state tracking is also used to know that the session can be failed over safely during planned operation as the session is unlikely to drain by itself even when not used.