System for destaging data during idle time by transferring to destage buffer, marking segment blank , reodering data in buffer, and transferring to beginning of segment

摘要

A disk storage architecture called DCD, Disk Caching Disk, for optimizing I/O performance. The DCD uses a small log disk, referred to as cache-disk, in the range of tens of MB as a secondary disk cache to optimize write performance. While the cache-disk and the normal data disk have the same physical properties, the access speed of the former differs dramatically from the latter because of different data units and different ways in which data are accessed. The objective is to exploit this speed difference by using the log disk as a cache to build a reliable and smooth disk hierarchy.