High-performance file system design

File systems and I/O subsystems should be smart; they can analyze how they are being used and tune themselves dynamically to improve their performance. File systems should select caching and disk placement strategies on a per-file basis, and they should use system-wide disk reorganization strategies. For example, systems should be able to reorganize the data on disk automatically during idle periods so that system performance is improved during future periods of peak load. This dissertation presents the design and analysis of iPcress, a prototype of a next-generation file system. iPcress is a smart, high-performance, reliable file system. It uses statistical information collected on a per-file basis to tune itself. iPcress has a framework in which various optimizations can be performed by the file system automatically. It is extensible; other optimization techniques can be incorporated easily, so that the system may evolve. In addition, iPcress can incorporate a variety of file access and placement techniques and choose the best combination of techniques for each file dynamically. A sample smart optimization--clustering active disk data in the center of the disk--is described; it increases disk throughput up to 30%.