Operating System Support for Easy Development of Distributed File Systems

A number of new distributed file systems have been developed, but the development of such file systems is not a simple task because it requires the operating system kernel to be modified. We have therefore developed an operating system in which a new file system is implemented as an extension module separated from the kernel. The operating system makes the file system easy to debug by protecting the kernel from errors of the file system, and it differs from similar operating systems in that it avoids unnecessary performance degradation by enabling the protection level to be changed without modifying the source code. We have implemented this operating system on the basis of NetBSD 1.2 and confirmed that the file system can run more efficiently when the protection level is decreased.