Improving Hybrid Multi-Level I/O Cache Lifetime Using Conservative Cache Management

Hybrid cache architectures are promising solutions for designing efficient I/O caching schemes. Oneof the major challenges of hybrid caches is the management of read miss data pages. As such pages are non-critical in term of data reliability, they can be buffered in volatile memories such as DRAM as an Endurance Friendly (EF) solution. Low capacity of DRAM, however, provides small hit ratio for these pages. A state-of-the-art solution has proposed a State-Machine Based Insertion (SMBI) scheme in order to improve cache performance by inserting read miss data pages in a Solid-State Drive (SSD), based on a static time periods. Nevertheless, the static approach of SMBI leads to considerable cache lifetime degradation compared to EF policy. In this paper, we propose Conservative State-Machine based Insertion (CSMI) scheme to improve I/O cache lifetime. CSMI dynamically adjusts the time that state-machine exploits EF approach based on workload behavior. To this end, CSMI employs a Conservative Factor (CF), which multiplies the number of periods that EF policy is exploited in case of low hit ratio. Our evaluations show that CSMI reduces the number of SSD writes up to 33.97%, compared to state-of-the art solution with negligible performance overhead (average of 0.06%).