Managing filesystem types

Managing filesystem types

UnixWare supports multiple filesystem types of varying characteristics. On UNIX^® systems, a file is a string of bytes (with no other structure implied) that resides in a directory. The directory (merely another type of file) is part of a hierarchy of directories which, together with the files it supports, makes up a filesystem. The following figure illustrates this structure: the circles represent directories; the command names below them, files.

A UNIX filesystem

The starting point of any UNIX filesystem is a directory that serves as the root of that filesystem. UNIX systems always have one filesystem that has the name ``root.'' Traditionally, the root directory of the root filesystem is represented by a single slash (/). The filesystem shown in the figure is a root filesystem. If you mount another filesystem onto the root filesystem at a directory called /var, the result looks like the diagram in the next figure.

Adding the /var filesystem

A directory such as /var that forms the connection between the root filesystem and another mountable filesystem is sometimes called a ``leaf'' or ``mount point.'' Regardless of the term used, such a directory is the root of the filesystem that descends from it. The name of that filesystem is the name of the directory. In the example, the name of the filesystem is /var.

The diagram in the previous two figures represents the file and directory structure of filesystems, but they do not illustrate how UnixWare systems view a filesystem. The sections that follow describe filesystem types as they appear to the operating system.

Due to the great range of filesystem types, only the seven most common are addressed here: s5, ufs, sfs (the secure filesystem), memfs, vxfs (the VERITAS filesystem type), bfs (the boot filesystem type), and dosfs. Information on other filesystem types is available elsewhere: /proc is described in proc(4) and the nfs filesystem type in ``Overview of NFS''.