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

sets the high water mark to 300 megabytes. The change takes effect after you

rebuild the HP-UX kernel using the mk_kernel command. You specify the

vx_bc_bufhwm tunable in units of kilobytes. The minimum value is 6144.

Increasing the value of vx_bc_bufhwm increases the VxFS buffer cache immediately,

allowing a greater amount of memory to be used to cache VxFS metadata.

Decreasing the value of vx_bc_bufhwm decreases the VxFS buffer cache to the

specified value. This frees memory such that the amount of memory used for

buffer cache is lower than the specified value of vx_bc_bufhwm.

Typically, the default value computed by VxFS based on the amount of system

memory ensures good system performance across a wide range of applications.

For application loads that cause frequent file system metadata changes on the

system (for example, a high rate of file creation or deletion, or accessing large

directories), changing the value of vx_bc_bufhwm may improve performance.

You can use the vxfsstat command to monitor buffer cache statistics and inode

cache usage.

See the vxfsstat(1M) manual page.

Number of links to a file

In VxFS, the number of possible links to a file is determined by the vx_maxlink

global tunable. The default value of vx_maxlink is 32767, the maximum value is

65535. This is a static tunable.

You can set the value of vx_maxlink using the sam or kctune commands.

See the sam(1M) and kctune(1M) manual pages.

You can also add an entry to the system configuration file as shown in the following

example:

vxfs_maxlink vx_maxlink 40000

This sets the value of vx_maxlink to 40,000 links.

VxFS inode free time lag

In VxFS, an inode is put on a freelist if it is not being used. The memory space for

this unused inode can be freed if it stays on the freelist for a specified amount of

time. The vx_ifree_timelag tunable specifies the minimum amount of time an

unused inode spends on a freelist before its memory space is freed.

The vx_ifree_timelag tunable is dynamic. Any changes to vx_ifree_timelag

take effect immediately.

VxFS performance: creating, mounting, and tuning file systems

Tuning the VxFS file system