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

Chapter 4
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4 Application Interface
Introduction
The VERITAS File System (VxFS) provides enhancements that can be used by applications that require
certain performance features. This chapter describes cache advisories and provides information about fixed
extent sizes and reservation of space for a file.
If you are writing applications, you can optimize them for use with the VxFS. To optimize VxFS for use with
applications, see Chapter 2, “VxFS Performance: Creating, Mounting, and Tuning File Systems,” on page 29.
The following topics are covered in this chapter:
• Cache Advisories
— Direct I/O
— Unbuffered I/O
— Discovered Direct I/O
— Data Synchronous I/O
— Other Advisories
• Extent Information
— Space Reservation
— Fixed Extent Sizes
• Freeze and Thaw
• Get I/O Parameters ioctl