A new hierarchical disk architecture

Large RAM caches are generally used to speed up disk accesses. Such caches more eeectively improve read performance than write performance, since write requests must be frequently written into disks to protect them from data loss or damage due to system failures. While Non-volatile RAM (NVRAM) caches can be used to improve write performance, large NVRAM caches are too expensive for many applications. This paper presents a new disk cache architecture called DCD, Disk Caching Disks. DCD takes the advantage of large data transfer sizes and uses inexpensive disk space to provide a high-performance, low-cost and reliable caching solution.