VERITAS File System 4.1 Administrator's Guide

Chapter 3 69
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 80). The extent allocation policies associated with a file are referred to as extent
attributes.
The VxFS getext(1M) and setext(1M) 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