Veritas File System 4.1 Administrator's Guide (HP-UX 11i v3, February 2007)

The VERITAS File System
Disk Layouts
Chapter 1 3
Disk Layouts
The disk layout is the way file system information is stored on disk. On VxFS, five disk layout versions,
numbered 1 through 5, were created to support various new features and specific UNIX environments.
Currently, only Version 4 or Version 5 disk layouts can be created, but file systems with Version 2 and
Version 3 disk layouts can be mounted.
See “Disk Layout” on page 229 for a description of the disk layouts.
File System Performance Enhancements
Traditional file systems employ block based allocation schemes. This provides adequate random access and
latency for small files, but limits throughput for larger files As a result, they are less than optimal for
commercial environments.
VxFS addresses this file system performance issue through an alternative allocation method and increased
user control over allocation, I/O, and caching policies. An overview of the VxFS allocation policy is
provided in the section “Extent Based Allocation” on page 6.
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
Tunable I/O parameters
Tunable indirect data extent size
Integration with VERITAS Volume Manager™ (VxVM®)
Support for improved database performance