System Administration Guide, Volume 1

Free Blocks

Blocks 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 appearance of a typical UFS file system, The figure below shows a series of cylinder groups in a generic UFS file system.

Figure 40-2 A Typical UFS File System