System Administration Guide: Devices and File Systems

Free Blocks

Blocks that are not currently being used as inodes, as indirect address blocks, or as storage blocks are marked as free in the cylinder group map. This map also keeps track of fragments to prevent fragmentation from degrading disk performance.

To give you an idea of the structure of a typical UFS file system, the following figure shows a series of cylinder groups in a generic UFS file system.

Figure 23–2 A Typical UFS File System

Graphic of UFS cylinder groups with boot blocks (8 Kbytes
in cylinder group 0 only), superblock, cylinder group map, inodes, and storage