Question

I need a simple explanation or introduction for Acyclic Graph directories and General Graph Directories. I Google for it, but the explanations were too technical.

Answer 1

Acyclic Graph Directories:

• Allow directories to link to one another, allow multiple directories
  to contain same file i.e., only one copy of the file exists and any
  change in the file can be viewed by all directories in which it is
  contained.
• Results in Acyclic graphs
• Two users can name same file or same directory
• Duplicate paths may complicate task of backing up periodically

General Graph Directories:

• Allow cycles
• More flexible
• More costly
• Need garbage collection (circular structures)
• There could be a subset of directories all with reference count > 0,
  but none of these are reachable from the root