These would be found on hard disks, CD-ROMs and DVDs. Files are stored in a sequence of bytes on fixed-sized blocks calIed sectors; these filesystems feature random-access file reads and writes, and also file fragmentation across the disk. Some disk-based filesystems also havejournalling and versioning. In a Journalling file system like XFS on the Silicon Graphics platform, changes in files are logged first in a specially-allocated area called a Journal before they're actually written on the main filesystem. Versioning filesystems like OpenVMS allow for the existence of several versions of the same file, and take periodic backups.
Popular disk-based filesystems include:

Windows: New Technology File System (NTIS), File Allocation Table (FAT, FAT16, FAT32), and many more; Linux: ext, ext2, ext2fs, NSS, ReiserFS and several others based on Linux and Unix variants Mac OS X: Hierarchical filesystem (HFS+), HFS, Macintosh filesystem (MFS), Xsan Disk-based filesystems can be further classiŽfied into:

Solid-state media filesystems: These are designed for storing files on devices that rely on Flash memory as their storage. Such filesystems require special handling, because data blocks wear out if information is repetitively written and rewritten on the drive. Besides, the blocks have to 1;?e erased explicitly before any data is written on them. The Journaling Flash filesystem UFFS) and Yet Another Flash filesystem (YAFFS). are popular solid-state filesystems. Record-oriented filesystems: The basic purpose of such filesystems is to store files in the form
of records to be compatible with older operating systems that are used exclusively on mainframes and minicomputers.

Shared-disk filesystem: These are also known as SAN (StorŽage Area Network) file systems or Cluster filesystem. As the name suggests, they are used on huge blocks of storage which are directly accessible to computers via a network connection.