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

Chapter 1 31
The VxFS File System
Application Interface
Application Interface
The VxFS file system 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
Chapter 6 , “Application Interface.”
Application Transparency
In most cases, any application designed to run on the HFS file system
should run transparently on the VxFS file system.
Expanded Application Facilities
The HP OnLineJFS product 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
Since these facilities are provided using VxFS-specific ioctl system calls,
most existing UNIX system applications do not use these facilities. The
cp, cpio, and mv utilities use these 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 should check what file system type they are using
before using these interfaces.