HP-UX Reference (11i v2 03/08) - 1M System Administration Commands N-Z (vol 4)

v
vxtunefs(1M) vxtunefs(1M)
NAME
vxtunefs - tune a VxFS File System
SYNOPSIS
vxtunefs [-ps][-f
tunefstab ][-o parameter =value][{mount_point |block_special}]...
DESCRIPTION
vxtunefs sets or prints tuneable I/O parameters of mounted file systems.
vxtunefs can set parame-
ters describing the I/O properties of the underlying device, parameters to indicate when to treat an I/O as
direct I/O, or parameters to control the extent allocation policy for the specified file system.
With no options specified,
vxtunefs
prints the existing VxFS parameters for the specified file systems.
vxtunefs works on a list of mount points specified on the command line, or all the mounted file systems
listed in the tunefstab file. The default
tunefstab file is /etc/vx/tunefstab
. You can change
the default using the
-f option.
vxtunefs can be run at any time on a mounted file system, and all parameter changes take immediate
effect. Parameters specified on the command line override parameters listed in the
tunefstab file.
If
/etc/vx/tunefstab
exists, the VxFS-specific
mount command invokes vxtunefs to set device
parameters from
/etc/vx/tunefstab
.
If the file system is built on a VERITAS Volume Manager (VxVM) volume, the VxFS-specific
mount_vxfs command interacts with VxVM to obtain default values for the tunables, so you need to
specify tunables for VxVM devices only to change the defaults.
Only a privileged user can run
vxtunefs.
Options
vxtunefs recognizes the following options:
-f filename Use filename instead of /etc/vx/tunefstab
as the file containing tuning
parameters.
-o parameter =value
Specify parameters for the file systems listed on the command line. See the "VxFS
Tuning Parameters and Guidelines" topic in this section.
-p Print the tuning parameters for all the file systems specified on the command line.
-s Set the new tuning parameters for the VxFS file systems specified on the command
line or in the tunefstab file.
Operands
vxtunefs recognizes the following operands:
mount_point Name of directory for a mounted VxFS file system.
block_special Name of the block_special device which contains the VxFS file system.
Notes
vxtunefs works with Storage Checkpoints; however, VxFS tunables apply to an entire file system.
Therefore tunables affect not only the primary fileset, but also any Storage Checkpoint filesets within that
file system.
The tunables
buf_breakup_sz, qio_cache_enable,
pref_strength, read_unit_io, and
write_unit_io are not supported on HP-UX.
VxFS Tuning Parameters and Guidelines
The values for all the following parameters except
read_nstream and write_nstream can be
specified in bytes, kilobytes, megabytes or sectors (1024 bytes) by appending k, K, m, M, s,orS.Youdo
not need for a suffix for the value in bytes.
If the file system is being used with a hardware disk array or another volume manager (such as VxVM),
align the parameters to match the geometry of the logical disk. For disk striping and RAID-5
configurations, set
read_pref_io to the stripe unit size or interleave factor and set read_nstream to
be the number of columns. For disk striping configurations, set write_pref_io and
write_nstream to the same values as read_pref_io and read_nstream, but for RAID-5
configurations, set write_pref_io, to the full stripe size and set write_nstream to 1.
HP-UX 11i Version 2: August 2003 − 1 − Hewlett-Packard Company Section 1M−−909