For systems that share the same buffer space for all files that are being read or written, try to predict the needed buffer space per file to prevent buffer over-allocation. Compaction and fragmentation Main goal is to place files on the disk in a way that facilitates access to them without wasting too much space. IBM operating systems and devices are prevalent. Many IBM devices have become industrial standards. There is usually at most one pending request for a disk.
Most disks have only one open file.