SSD internal cache management policies: A survey

SSDs are now increasingly being adopted as primary nonvolatile storage in diverse domains. The internal caches in the SSDs boost SSD performance, lifetime, and robustness. There are three types of internal caches: data cache and mapping cache in the SSD front-end, and flash-based cache in the SSD back-end; they are designed to meet specific requirements like controlling traffic to the back-end, optimization of response time, improving SSD lifetime etc. The underlying memory technology also influences cache design decisions.