A Flash-Based SSD Cache Management Scheme for High Performance Home Cloud Storage

In the home cloud environment, storage performance is the most important factors affecting the user experience. In order to improve storage performance, we introduce a technique for managing flash-based storage devices as a cache. Although there are various studies on the use of flash caches, we focus on managing read requests that take into account flash memory characteristics and destaging methods from solid state drive cache to hard disk drives (HDDs) to improve performance. In this paper, we propose a scheme for managing flash-based solid state cache (SSC) called hybrid unit 2level-least recently used to improve input/output performance of HDD-based storage. Through the proposed scheme, cache hit ratio is increased and the number of disk access is reduced by keeping frequently accessed pages in SSC. In addition, the disk head movement is reduced when pages are destaged to disk by grouping write requested pages with adjacent pages. The number of cached pages is dynamically adjusted according to the ratio of read and write requests to improve performance on various workloads. For performance evaluation, we implemented the proposed scheme in a trace-based simulator. Performance evaluation shows up to 51% reduction in execution time compared to existing representative schemes.