VERITAS File SystemÖ 3.5 (HP OnlineJFS/JFS3.5) AdministratorÆs Guide (December 2002)

Chapter 1

The VERITAS File System

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 43.

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.