Introduction
In addition to primary memory (volatile), computer systems provide users secondary storage units which may be used for persistent (or permanent) storage.
A file is a collection of data elements grouped together for the purposes of access control, retrieval and modification.
A file system together with IO management subsystem accomplish the mapping of abstract user interface into the actual collection of hardware such as disk, tape etc. of varying characteristics.
Recently there has been lot of interest in a storage medium called RAID. We will look into this (11.6)
We will study IO management in this discussion (Ch.11) and File system in the next chapter (Ch. 12)