Disk space control

We placed the control of disk space into the directories. Rather than have accounting blocks to control space as in the ECS system, we decided it would be simpler to assign disk space to the directories. When a directory was created it was specified to be an accounting directory or not. Whenever disk space was needed to create or enlarge a file or other disk object, the disk tree was scanned starting with the object and moving towards the root directory until an accounting directory was found. This accounting directory was then checked to see if it had sufficient available space for the action intended, and if so, the available space was reduced. (To save time, a pointer was placed in each directory to point back to its associated accounting directory.) Each user was assigned an accounting directory and given space in it. The user could build as large a tree as he desired from this directory, within the limits of the space he was given. He could even create subuser directories. Using this mechanism we could delegate the authority for making user directories to individual departments of the university, thus reducing the clerical work of the computer center.