VERITAS File System 4.1 Administrator's Guide

The VERITAS File System
Application Interface
Chapter 1 23
Application Interface
VxFS conforms to the System V Interface Definition (SVID) requirements and supports user
access through the Network File System (NFS). Applications that require performance
features not available with other file systems can take advantage of VxFS enhancements that
are introduced in this section and covered in detail in “Application Interface” on page 75.
Application Transparency
In most cases, any application designed to run on native file systems will run transparently
on VxFS.
Expanded Application Facilities
VxFS provides some facilities frequently associated with commercial applications that make
it possible to:
• Preallocate space for a file
• Specify a fixed extent size for a file
• Bypass the system buffer cache for file I/O
• Specify the expected access pattern for a file
Because these facilities are provided using VxFS-specific ioctl system calls, most existing
UNIX system applications do not use them. The cp, cpio, and mv utilities use the facilities to
preserve extent attributes and allocate space more efficiently. The current attributes of a file
can be listed using the getext command or ls command. The facilities can also improve
performance for custom applications. For portability reasons, these applications must check
which file system type they are using before using these interfaces.