Abstract: A distributed file system for a multi-processor system having multiple nodes, each node having a client processor and a client disk. The nodes are connected to a communications fabric for passing files between the nodes. One of the nodes acts as a server for passing files from the server to any of the other nodes. When a client processor reads a file on its client disk, the client processor obtains the server copy of the file and installs it on the client disk if the server copy of the file is more current, before the read operation. Provision is also made for atomically providing upgrades of application files to the client disks. When the client processor writes to a file, it sets a write flag in the file so that the file thus written to by the client processor is invisible to file operations from the server and the other nodes. The disclosed file system is particularly useful for systems administration of a multi-processor system having a single point of systems software install.