Veritas™ File System 5.0.1 Administrator's Guide

■ VxFS buffer cache high water mark
■ Number of links to a file
■ VxFS inode free time lag
Tuning inode table size
VxFS caches inodes in an inode table. There is a dynamic tunable in VxFS called
vx_ninode that determines the number of entries in the inode table. You can
dynamically change the value of vx_ninode by using the sam or kctune commands.
See the sam(1M) and kctune(1M) manual pages.
This value is used to determine the number of entries in the VxFS inode table. By
default, vx_ninode initializes at zero; the file system then computes a value based
on the system memory size.
A VxFS file system can also obtain the value of vx_ninode from the system
configuration file used for making the HP-UX kernel (/stand/system for example).
To change the computed value of vx_ninode, you can add an entry to the system
configuration file. For example:
tunable vx_ninode 1000000
This sets the inode table size to 1,000,000 inodes after making a new HP-UX kernel
using mk_kernel.
Increasing the value of vx_ninode increases the inode table size immediately,
allowing a higher number of inodes to be cached. Decreasing the value of vx_ninode
decreases the inode table size to the specified value. After the tunable is decreased,
VxFS attempts to free excess cached objects so that the resulting number of inodes
in the table is less than or equal to the specified value of vx_ninode. If this attempt
fails, the value of the vx_ninode tunable is not changed. In such a case, the kctune
command can be specified with the -h option so that the new value of vx_ninode
takes effect after a system reboot.
Be careful when changing the value of vx_ninode, as the value can affect file
system performance. Typically, the default value determined by VxFS based on
the amount of system memory ensures good system performance across a wide
range of applications. However, if it is determined that the default value is not
suitable, vx_ninode can be set to an appropriate value based on the expected file
system usage. The vxfsstat command can be used to monitor inode cache usage
and statistics to determine the optimum value of vx_ninode for the system.
Changing the value of a tunable does not resize the internal hash tables and
structures of the caches. These sizes are determined at system boot up based on
45VxFS performance: creating, mounting, and tuning file systems
Tuning the VxFS file system