The Logical Disk: A New Approach to Improving File Systems

The Logical Disk (LD) defines a new interface to disk storage that separates file management and disk management by using logical block numbers and block lists. The LD interface is designed to support multiple file systems and to allow multiple implementations, both of which are important given the increasing use of kernels that support multiple operating system personalities. A log-structured implementation of LD (LLD) demonstrates that LD can be implemented efficiently. LLD adds about 5 % to 10 % to the purchase cost of a disk for the main memory it requires. Combining LLD with an existing file system results in a log-structured file system that exhibits the same performance characteristics as the Sprite log-structured file system