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

Chapter 1 35
The VxFS File System
Enhanced I/O Performance
Enhanced I/O Performance
VxFS provides enhanced I/O performance by applying an aggressive I/O
clustering policy.
Enhanced I/O Clustering
I/O clustering is a technique of grouping multiple I/O operations together
for improved performance. The VxFS I/O policies provide more
aggressive clustering processes than other file systems and offer higher
I/O throughput when using large files; the resulting performance is
comparable to that provided by raw disk.
Application-Specific Parameters
System administrators can also set application specific parameters on a
per-file system basis to improve I/O performance.
Default Indirect Extent Size
On disk layout Version 2, this value can be set up to apply to all the
indirect extents, provided a fixed extentsize is not already set andthe
file does not already have indirect extents. The Version 3 and 4 disk
layout uses typed extents which have variable sized indirects.
Discovered Direct I/O
All sizes above this value would be performed as direct I/O.
NOTE The Discovered Direct I/O parameter is available only with the HP
OnLineJFS product.
Maximum Direct I/O Size
This value defines the maximum size of a single direct I/O.
NOTE The Maximum Direct I/O Size parameter is available only with the HP
OnLineJFS product.