CFDC: A Flash-Aware Buffer Management Algorithm for Database Systems

Classical buffer replacement policies, e.g., LRU, are suboptimal for database systems having flash disks for persistence, because they are not aware of the distinguished characteristics of those storage devices. We present CFDC (Clean-First Dirty-Clustered), a flash-aware buffer management algorithm, which emphasizes that clean buffer pages are first considered for replacement and that modified buffer pages are clustered for better spatial locality of page flushes. Our algorithm is complementary to and can be integrated with conventional replacement policies. Our DBMS-based performance studies using both synthetic and real-life OLTP traces reveal that CFDC significantly outperforms previous proposals with a performance gain up to 53%.