VERITAS File System 3.5 (HP OnlineJFS/JFS 3.5) Administrator's Guide (August 2003)

Chapter 3
49
3 Extent Attributes
Introduction
The VERITAS File System (VxFS) allocates disk space to files in groups of one or more adjacent blocks called
extents. VxFS defines an application interface that allows programs to control various aspects of the extent
allocation for a given file (see “Extent Information” on page 58). The extent allocation policies associated with
a file are referred to as extent attributes.
The VxFS getext and setext commands let you view or manipulate file extent attributes. In addition, the
vxdump, vxrestore, mv, cp, and cpio commands preserve extent attributes when a file is backed up, moved,
copied, or archived.
The following topics are covered in this chapter:
• Attribute Specifics
— Reservation: Preallocating Space to a File
— Fixed Extent Size
— Other Controls
• Commands Related to Extent Attributes
— Failure to Preserve Extent Attributes