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

22 Chapter1
The VxFS File System
File System Performance Enhancements
File System Performance Enhancements
The HFS file system uses block based allocation schemes which provide
adequate random access and latency for small files but limit throughput
for larger files. As a result, the HFS file system is less than optimal for
commercial environments.
VxFS addresses this file system performance issue through an
alternative allocation scheme and increased user control over allocation,
I/O, and caching policies. An overview of the VxFS allocation scheme is
covered in the section “Extent-Based Allocation”.
VxFs provides the following performance enhancements:
• extent based allocation
• enhanced mount options
• data synchronous I/O
• direct I/O and discovered direct I/O
• caching advisories
• enhanced directory features
• explicit file alignment, extent size, and preallocation controls
• tuneable I/O parameters
• tuneable indirect data extent size
The rest of this chapter along with Chapter 5 , “Performance and
Tuning” and Chapter 6 , “Application Interface” provide more details
on some of these features.