Veritas™ File System 5.0.1 Administrator's Guide

Note: Thin Reclamation is a slow process and may take several hours to complete,
depending on the file system size. Thin Reclamation is not guaranteed to reclaim
100% of the free space.
You can track the progress of the Thin Reclamation process by using the vxtask
list command when using the Veritas Volume Manager (VxVM) command vxdisk
reclaim.
See the vxtask(1M) and vxdisk(1M) manual pages.
You can administer Thin Reclamation using VxVM commands.
See the Veritas Volume Manager Administrator's Guide.
Tuning I/O
The performance of a file system can be enhanced by a suitable choice of I/O sizes
and proper alignment of the I/O requests based on the requirements of the
underlying special device. VxFS provides tools to tune the file systems.
Note: The following tunables and the techniques work on a per file system basis.
Use them judiciously based on the underlying device properties and characteristics
of the applications that use the file system.
Tuning VxFS I/O parameters
VxFS provides a set of tunable I/O parameters that control some of its behavior.
These I/O parameters are useful to help the file system adjust to striped or RAID-5
volumes that could yield performance superior to a single disk. Typically, data
streaming applications that access large files see the largest benefit from tuning
the file system.
VxVM queries
VxVM receives the following queries during configuration:
■ The file system queries VxVM to determine the geometry of the underlying
volume and automatically sets the I/O parameters.
Note: When using file systems in multiple volume sets, VxFS sets the VxFS
tunables based on the geometry of the first component volume (volume 0) in
the volume set.
51VxFS performance: creating, mounting, and tuning file systems
Tuning I/O