Veritas File System 4.1 Administrator's Guide (HP-UX 11i v3, February 2007)

Disk Layout
Disk Layout
Appendix C 231
The Version 4 file system also moves away from the model of storing AU structural data at the start of an
AU and puts all structural information in files. So expanding the file system structures simply requires
extending the appropriate structural files. This removes the extent size restriction imposed by the previous
layouts.
All Version 4 structural files reside in the structural fileset. The structural files in the Version 4 disk layout
are:
object location table file Contains the object location table (OLT). The OLT, which is referenced from the
super-block, is used to locate the other structural files.
label file Encapsulates the super-block and super-block replicas. Although the location of the
primary super-block is known, the label file can be used to locate super-block copies if
there is structural damage to the file system.
device file Records device information such as volume length and volume label, and contains
pointers to other structural files.
fileset header file Holds information on a per-fileset basis. This may include the inode of the filesets
inode list file, the maximum number of inodes allowed, an indication of whether the file
system supports large files, and the inode number of the quotas file if the fileset
supports quotas. When a file system is created, there are two filesets-the structural
fileset defines the file system structure, the primary fileset contains user data.
inode list file Both the primary fileset and the structural fileset have their own set of inodes stored in
an inode list file. Only the inodes in the primary fileset are visible to users. When the
number of inodes is increased, the kernel increases the size of the inode list file.
inode allocation unit file Holds the free inode map, extended operations map, and a summary of inode
resources.
log file Maps the block used by the file system intent log.
extent allocation unit state file Indicates the allocation state of each AU by defining whether each AU is
free, allocated as a whole (no bitmaps allocated), or expanded, in which case the
bitmaps associated with each AU determine which extents are allocated.
extent allocation unit summary file Contains the AU summary for each allocation unit, which contains the
number of free extents of each size. The summary for an extent is created only when an
allocation unit is expanded for use.
free extent map file Contains the free extent maps for each of the allocation units.
quotas files There is a quotas file which is used to track the resources allocated to each user and a
quotas.grp file to track the resources allocated to each group.