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

Chapter 1
The VERITAS File System
Application Interface
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 55.
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.