File - Persistent Storage Operations

About

In a file system, the basic persistent storage operations that permits to manage the file content are called:

• create - Creates a new file and open it
• write - Opens the file for write access (append - Appends the new data to the end of the file)
• read - Opens the file for read access
• delete - Delete the file

They are part made through file system request.

Unit

File System

The local/os file system performs all requests against the hard drive at the cluster size and holds them in memory in a cache.

Application

An application using the OS API can thereafter read file content from the File System Cache:

• at its own block level (such as fixed sized database records, ..)
• as if the sectors was contiguous

This operation is known as the scatter-gather scheme ¹⁾

Lock

When the file system reads and writes file, file lock may be asked or taken in order to prevent data corruption.