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Global Tunable Parameters

There are various VxFS global tunable parameters that are set when VxFS is loaded. The default values calculated for these global tunables are based on the amount of memory available on the system. The default values do not change unless the amount of memory changes and VxFS is reloaded or the system is rebooted.

While the global parameter default values assure good system performance across a wide range of applications, if your system is caching a large number of metadata transactions, or if there is significant virtual memory manager usage, modifying some of the parameters may improve performance. VxFS has three global parameters that can be modified to improve performance under this condition:

vxfs_ninode	Sets the maximum number of inodes. VxFS caches inodes in an inode table and uses the value of vxfs_ninode as the maximum number of entries in the inode table.
vx_bc_bufhwm	Sets the maximum number of buffers in the VxFS buffer cache.
vx_vmm_buf_count	Sets the number of buffers allocated to the virtual memory manager (VMM).

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

See the vxfsstat(1M) manual page.

You can also monitor VMM buffer usage.

See File system tuning guidelines.

  Note   The tunable parameters provide tuning tools that can degrade system performance if not applied correctly. It is best to consult with Symantec Technical Support before altering the default parameters.