File Systems Overview

 
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(All of the files that are served by the server are just ordinary,
every-day files that are located in a special directory on the server.
We call this a Web Documents directory or folder.)

hard disk image Computers and Hard Disks
"All" of the information that is stored on a computer and stays there after the computer is turned off is stored on the hard disk: On a Mac, this is (sort of) represented by a computer icon somewhere on the desktop (e.g., at the top right -- figure to right). (On a Windows box, the hard disk is the "C:" drive in the "My Computer" icon at the top left of the desktop.)

disk organization Organization
Everything (almost) that is stored on the hard disk is a file, and these files are stored in directories -- called folders. On either a Mac or a Windows computer, double-clicking on the hard disk icon shows these directories and files, for example, as shown in the figure to the left. In this and in all cases we will choose to view the files and folder as a list, rather than as just icons, because this gives a better feel for how different files and directories are related. (On a Windows computer, this view is most easily obtained with the "Windows explorer," rather than the "My Computer" icon.)

subdirectories Subdirectories
Within any directory on the disk, there can be both files and other directories (subdirectories of the upper-level directory) -- as shown to the right. We think of a file system as this tree of directories starting with the top level of the hard disk. This is important because files on the Web are just files that are in a special subdirectory on a computer running special software.

There are two views of this: the list, with subdirectories shown indented below the containing directory as in the figure to the right, and with the directory shown as a new window (obtained by double clicking on it).

(Technically the disk can also be partitioned into different sections, each of which is separately represented as a hard disk or directory -- the hard disk itself is then like the "hard disk" image in the second picture above, with the partitions being like "directories" in the hard disk. The difference is that while a directory can fill up as much space as is available, the partition has a fixed size. It is at this point that we really talk about file systems, but we're not going to dwell on this subtlety.)

Important Stuff
  • Everything on a computer is on a Hard Disk,
  • Hard disks are divided into directories (folders) containing files,
  • The files that we put on the Web are placed in a special directory on a computer that acts as a Web server, and
  • We can organize our Web files on the server using a system of subdirectories.



Gavin's HHMI 02 Web Workshop: File Systems
Last Modified: Thu May 30 12:44:39 EDT 2002
Comments to glarose@umich.edu
©2002 Gavin LaRose, UM Math Dept