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

Chapter 2 71
Disk Layout
The VxFS Version 4 Disk Layout
The VxFS Version 4 Disk Layout
The Version 4 disk layout supports Access Control Lists.
The Version 4 disk layout does not include significant physical changes
from the Version 3 disk layout. Instead, the policies implemented for
Version 4 are different, allowing for performance improvements, file
system shrinking, and other enhancements.