Default Oracle Solaris File Systems

The ZFS or UFS file system is hierarchical, starting with the root directory (/) and continuing downwards through a number of directories. The Oracle Solaris installation process enables you to install a default set of directories and uses a set of conventions to group similar types of files together.

For a brief overview of Oracle Solaris file systems and directories, see filesystem(5).

The following table provides a summary of the default Oracle Solaris file systems.

Table 16-2 The Default Oracle Solaris File Systems

File System or Directory	File System Type	Description
root (`/`)	UFS or ZFS	The top of the hierarchical file tree. The root (`/`) directory contains the directories and files that are critical for system operation, such as the kernel, the device drivers, and the programs used to boot the system. The root (`/`) directory also contains the mount point directories where local and remote file systems can be attached to the file tree.
`/usr`	UFS or ZFS	System files and directories that can be shared with other users. Files that run only on certain types of systems are in the `/usr` file system or directory (for example, SPARC executables). Files that can be used on all types of systems, such as the man pages, might be placed in the `/usr/share` directory.
`/export/home` or `/home`	NFS, UFS, or ZFS	The mount point for user home directories, which store user work files. By default, the `/home` directory is an automounted file system. On stand-alone systems, the `/home` directory might be a UFS file system or a ZFS file system.
`/var`	UFS or ZFS	System files and directories that are likely to change or grow over the life of the local system. These include system logs, such as `vi` and `ex` backup files.
`/opt`	NFS, UFS or ZFS	Optional mount point for third-party software. On some systems, the `/opt` directory might be a UFS file system or ZFS file system.
`/tmp`	TMPFS	Temporary files, which are removed each time the system is booted or the `/tmp` file system is unmounted.
`/proc`	PROCFS	A list of active processes, by process number.
`/etc/mnttab`	MNTFS	A virtual file system that provides read-only access to the table of mounted file systems for the local system.
`/var/run`	TMPFS	A memory-based file system for storing temporary files that are not needed after the system is booted.
`/system/contract`	CTFS	A virtual file system that maintains contract information.
`/system/object`	OBJFS	A virtual file system that is used by debuggers to access information about kernel symbols without having to access the kernel directly.

The root (/) and /usr file systems are required to run a system. Some of the most basic commands in the /usr file system (like mount) are also included in the root (/) file system. As such, they are available when the system boots or is in single-user mode, and /usr is not mounted.

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	System Administration Guide: Devices and File Systems Oracle Solaris 10 8/11 Information Library