HP JFS 3.3 and HP OnLineJFS 3.3 VERITAS File System 3.3 System Administrator's Guide

58 Chapter2
Disk Layout
The VxFS Version 2 Disk Layout
inode allocation unit (IAU) file A file that contains a series of inode
allocation units.
current usage table (CUT) file A file that contains a series of fileset
usage entries.
link count table file A file that contains a link count for
each inode in the attribute fileset.
quotas file A file containing user quota
information (for the primary fileset
only).
Structural files and their components are discussed in the sections that
follow.
Although structural files are contained in the structural fileset, they can
“belong” to another fileset. For example, the inode list file for the primary
fileset is in the structural fileset, but the structural details that it
contains are only applicable to the primary fileset.
Each fileset is defined by structural files as follows:
• an inode list file, which contains the inodes belonging to the fileset
• an inode allocation unit file, which contains a series of inode
allocation units
• an entry in the fileset header file, which contains one fileset header
per fileset
• an entry in the current usage table file, which contains usage
information for each fileset
In addition, the primary fileset has a user quotas file and the structural
fileset has a link count table file.
Fileset metadata that cannot be reconstructed using the inode list is
replicated to help fsck reconstruct the file system in the event of disk
damage.
Figure 2-5, “Filesets and Structural Files” shows a fileset and the
structural files by which it is defined.
Fileset Header
Each fileset has a header containing information about the fileset’s
contents and characteristic. All fileset headers are stored in a single
fileset header file in the attribute fileset. The fileset header file contains