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

Chapter 2 51
Disk Layout
The VxFS Version 2 Disk Layout
The VxFS Version 2 Disk Layout
This section describes the VxFS Version 2 disk layout.
Due to the relatively complex nature of the Version 2 layout, the sections
that follow are arranged to cover the following general areas:
• Structural elements of the file system that exist in fixed locations.
These elements are discussed in “Basic Layout”.
• Structural elements of the file system that do not exist in fixed
locations. These elements are discussed in “Filesets and Structural
Files”.
• The location and use of the various structural elements when the file
system is mounted. This is discussed in “Locating Dynamic
Structures”.
Overview
Many aspects of the Version 1 disk layout are preserved in the Version 2
disk layout. However, the Version 2 layout differs from the Version 1
layout in that it includes support for the following features:
• filesets (sets of files within a file system)
• dynamic inode allocation (allocation of inodes on an as-needed basis)
• enhanced security
The addition of filesets and dynamic allocation of inodes has affected the
disk layout in various ways. In particular, many of the file system
structures are now located in files (referred to as structural files )
rather than in fixed disk areas. This provides a simple mechanism for
dynamic growth of structures. For example, inodes are now stored in
structural files and allocated as needed. In general, file system
structures that deal with space allocation are still in fixed disk locations,
while most other structures are dynamically allocated and have become
clients of the file system’s disk space allocation scheme.
The Version 2 disk layout adds BSD-style quota support. The differences
include the fileset header structure modification to store a quota inode
and preallocation of an internal quotas file.