PFS and Patsy: a new file system design methodology
Peter Bösch, Sape J. Mullender · 1995
The Pegasus File System (PFS) is a file system that has been designed to support a wide variety of (different) workloads. In PFS, it is relatively easy to replace policies by others to optimize for other workloads. Currently we have built a prototype log-structured file system in PFS to optimize for a Unix workload. It is an example of the configurability of PFS. Patsy is a file system simulator much like PFS. Patsy allows system programmers to experiment with storage algorithms and to measure the performance before those algorithms are integrated into a production file system. Since Patsy has a similar structure as PFS, migrating algorithms from Patsy to PFS is relatively easy. This paper describes the method we use to do file system research. File system algorithms and policies are analyzed off-line in Patsy, in so-called file system experiments. When algorithms or policies perform as expected in Patsy, they are migrated to a real file system (in this case PFS). Since Patsy and PFS a...