Veritas File System 5.1 SP1 Administrator"s Guide (5900-1499, April 2011)

■ Integration with VxVM™
■ Support for large directories
Note: VxFS reduces the file lookup time in directories with an extremely large
number of files.
About enhanced I/O performance
VxFS provides enhanced I/O performance by applying an aggressive I/O clustering
policy, integrating with VxVM, and allowing application specific parameters to
be set on a per-file system basis.
See “Enhanced I/O clustering” on page 29.
See “Veritas Volume Manager integration with Veritas File System for enhanced
I/O performance” on page 29.
See “Application-specific parameters for enhanced I/O performance” on page 29.
Enhanced I/O clustering
I/O clustering is a technique of grouping multiple I/O operations together for
improved performance. 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.
Veritas Volume Manager integration with Veritas File System
for enhanced I/O performance
VxFS interfaces with VxVM to determine the I/O characteristics of the underlying
volume and perform I/O accordingly. VxFS also uses this information when using
mkfs to perform proper allocation unit alignments for efficient I/O operations
from the kernel.
As part of VxFS/VxVM integration, VxVM exports a set of I/O parameters to
achieve better I/O performance. This interface can enhance performance for
different volume configurations such as RAID-5, striped, and mirrored volumes.
Full stripe writes are important in a RAID-5 volume for strong I/O performance.
VxFS uses these parameters to issue appropriate I/O requests to VxVM.
Application-specific parameters for enhanced I/O performance
You can set application specific parameters on a per-file system basis to improve
I/O performance.
29Introducing Veritas File System
Veritas File System performance enhancements