For directories larger than 100,000 articles, Usenetfs improves performance by more than an order of magnitude. For directories containing 10,000 articles or more it improves performance by at least several factors. Usenetfs provides more efficient utilization of existing hardware, thus extending its lifetime in the face of ever increasing news traffic.
We have shown that a relatively portable and highly stable file system can be written in a short period of time. The short development time and higher portability than native file systems were both the result of designing and implementing Usenetfs as a stackable vnode interface file system.
Stackable file systems and stackable vnodes are not a new idea, but they have seen very little use. With this work, we hope to prove that a lot can be accomplished with little effort and without the need to rewrite any application software, design radically new disk-based file systems, or redesign operating systems. We believe that many more stackable file systems can be written for existing vnode interfaces. But we also recognize that in the long run, a truly stackable vnode interface would have to be designed for modern operating systems in order to maximize its utility. We also believe that while more cumbersome and difficult to develop, new file systems coupled with a new data storage models for news are the better long term solutions to performance problems of USENET news systems.
Next we plan to complete our port of Usenetfs to Solaris and also port it to FreeBSD, since these are representative of the other two major Unix flavors in use.