Track-based disk logging

摘要

Disk logging is a fundamental building block for fault tolerance system design because it captures a persistent snapshot of critical system state for subsequent recovery in the occurrence of failures. Logging typically is required to be synchronous to ensure absolute recoverability. Therefore speeding up synchronous disk write is critical to those fault tolerance systems that are based on disk logging. This paper describes a novel track-based disk logging technique that is able to reduce the latency of synchronous disk writes to the minimum without compromising data integrity guarantee. As an application of track-based disk logging, we present the design and implementation of a low-write-latency disk subsystem called Trail. Through a fully operational Trail prototype, we demonstrate that Trail achieves the best known disk. logging performance record, which is close to data transfer delay plus command processing overhead. A 4 KByte disk write takes less than 1.5 msec. Based on the TPC-C benchmark, the transaction throughput of a Trail-based transaction processing system is on an average 62.9% higher-than one based on a standard disk subsystem, and the database logging-related disk I/O overhead is reduced by 42%.