HP-UX HB v13.00 Ch-14 - JFS

HP-UX Handbook – Rev 13.00 Page 16 (of 47)
Chapter 14 Journaled File System (JFS)
October 29, 2013
Veritas File System performance enhancements
Traditional file systems employ block-based allocation schemes that provide adequate random
access and latency for small files, but which limit 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.
VxFS provides the following performance enhancements:
• Data synchronous I/O
• Direct I/O and discovered direct I/O
• Support for files and file systems up to 256 terabytes
• Support for files up to 2 terabytes
• Enhanced I/O performance
• Caching advisories
• Enhanced directory features
• Explicit file alignment, extent size, and pre-allocation controls
• Tunable I/O parameters
• Tunable indirect data extent size
• Integration with VxVM
• Support for large directories
Note: VxFS reduces the file lookup time in directories with an extremely large
number of files.
Improving I/O using vxtunefs
This command can be used to print or set tunable I/O parameters of mounted file systems. The
I/O parameters are:
 Parameters describing the I/O properties of the underlying device
 Parameters to indicate when to treat an I/O as direct I/O
 Parameters to control the extend allocation policy for the specific file systems
It works on a list of mount points specified on the command line or all the mounted file systems
listed in the tunefstab file, which is in /etc/vx/tunefstab. The change of the parameters takes place
immediately.
To print the values, type the following command:
# vxtunefs -p mount_point