VERITAS File System 4.1 Administrator's Guide

Chapter 4 75

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 37.

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

• Named Data Streams

• Named Data Streams Programmatic Interface

— Listing Named Data Streams

— Namespace for Named Data Streams

— Behavior Changes in Other System Calls