Disk-based File Systems

Disk-based file systems are stored on physical media such as hard disks, CD-ROMs, and diskettes. Disk-based file systems can be written in different formats. The available formats are:

• UFS - UNIX file system (based on the BSD Fast File system that was provided in the 4.3 Tahoe release). UFS is the default disk-based file system for the Solaris operating environment.

  Before you can create a UFS file system on a disk, the disk must be formatted and divided into slices. A disk slice is a physical subset of a disk that is composed of a single range of contiguous blocks. A slice can be used either as a raw device that provides, for example, swap space, or to hold a disk-based file system. See Chapter 21, Disk Management (Overview) for complete information on formatting disks and dividing disks into slices.

• HSFS - High Sierra and ISO 9660 file system. High Sierra is the first CD-ROM file system; ISO 9660 is the official standard version of the High Sierra File System. The HSFS file system is used on CD-ROMs, and is a read-only file system. Solaris HSFS supports Rock Ridge extensions to ISO 9660, which, when present on a CD-ROM, provide all UFS file system semantics and file types except for writability and hard links.

• PCFS - PC file system, which allows read/write access to data and programs on DOS-formatted disks written for DOS-based personal computers.

Each type of disk-based file system is customarily associated with a particular media device:

• UFS with hard disk

• HSFS with CD-ROM

• PCFS with diskette

These associations are not, however, restrictive. For example, CD-ROMs and diskettes can have UFS file systems created on them.