Crashherstel

Crashherstel is a term used in Dutch-language information technology to describe the processes and techniques involved in restoring a computing system after a crash and preserving data integrity and service continuity. It spans layers from applications and database engines to file systems and operating systems, and it focuses on preventing data loss and reducing downtime following an incident.

The central goals of crashherstel are to minimize data loss (recovery point objective, or RPO) and to restore normal operation as quickly as possible (recovery time objective, or RTO), while maintaining the consistency of stored information. This requires careful management of state, logs, and intermediate results so that systems can return to a valid state after unexpected failures.

Common approaches include write-ahead logging and journaling, where change records are written before they are applied to the main data structures; checkpointing to record the system state at intervals; and crash-consistent file systems that use copy-on-write or similar techniques. In practice, crashherstel combines these methods with replication, redundancy, and reliable power and storage subsystems to improve resilience.

In databases, crashherstel relies on logs to redo committed transactions and undo incomplete ones after a crash. In file systems, journaling tracks metadata changes to ensure recoverability, while advanced file systems with copy-on-write semantics provide stronger crash resistance. Operating systems implement crash recovery routines to recover kernel and user-space state after crashes or power failures.

Challenges include partial writes, hardware faults, and cache effects that complicate recovery. Best practices emphasize robust testing, including fault injection and chaos engineering, and the use of redundant infrastructure and durable storage to support effective crashherstel.