For security, directory encryption can be used. The bullet service is a simple file server that maintains immutable files. It stores files contiguously on disk and in cache. When creating a file, the entire file data is provided and the file's capability is returned. The user can then choose a file name for the file give it to the directory service along with its capability so the service can enter the new mapping in some directory.
Fragmentation is a problem.
No solutions mentioned. A process consists of a segmented virtual address space and one or more threads. A process can only run on a machine whose kernel matches its host descriptor. To create a process, an execute-process request is sent to a kernel along with a descriptor for the process. Processes control their address space explicitly.