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

66 Chapter2
Disk Layout
The VxFS Version 2 Disk Layout
• The number of blocks currently used by the fileset.
• The fileset version number , which is a 64-bit integer that is
guaranteed to be at least as large as the largest inode version
number. An inode version number is a 64-bit integer that is
incremented every time its inode is modified or written to disk and
can be used to indicate whether an inode has been modified in any
way since the last time it was examined. It is possible to find out
which inodes have been modified since a specific time by saving the
fileset version number and then later looking for inodes with a larger
version number.
Figure 2-9 Current Usage Table (CUT) File
Quotas File
VxFS supports BSD-style quotas for users. Quota information is stored
in a quotas file. A user quotas file tracks the resources used by each user
ID. The quotas file keeps track of soft limits, hard limits, block usage,
and inode usage for users within a file system.
Because quotas apply to mountable filesets only, the attribute fileset does
not have quotas. However, the primary fileset’s quotas file exists as a
structural file in the attribute fileset. The primary fileset’s user quotas
file is referenced by the structural fileset’s initial inode list extent.
Locating Dynamic Structures
The existence of dynamic structures in the Version 2 disk layout makes
the task of initially locating those structures difficult. The object location
table (OLT) contains information needed to initially locate important file
system structural elements. In particular, the OLT records the starting
Attribute Fileset CUT Entry
Primary Fileset CUT Entry
. . .