Veritas File System 5.0 AdministratorÆs Guide, HP-UX 11i v3, First Edition, May 2008

The vxtunefs command can be used to print the current values of the I/O
parameters.
To print the values, type the following command:
# vxtunefs -p mount_point
The following is an example tunefstab file:
/dev/vx/dsk/userdg/netbackup
read_pref_io=128k,write_pref_io=128k,read_nstream=4,write_nstream=4
/dev/vx/dsk/userdg/metasave
read_pref_io=128k,write_pref_io=128k,read_nstream=4,write_nstream=4
/dev/vx/dsk/userdg/solbuild
read_pref_io=64k,write_pref_io=64k,read_nstream=4,write_nstream=4
/dev/vx/dsk/userdg/solrelease
read_pref_io=64k,write_pref_io=64k,read_nstream=4,write_nstream=4
/dev/vx/dsk/userdg/solpatch
read_pref_io=128k,write_pref_io=128k,read_nstream=4,write_nstream=4
Tunable I/O parameters
Table 2-1 provides a list and description of these parameters.
Table 2-1
Tunable VxFS I/O parameters
DescriptionParameter
The preferred read request size. The file system uses this
in conjunction with the read_nstream value to
determine how much data to read ahead. The default value
is 64K.
read_pref_io
The preferred write request size. The file system uses this
in conjunction with the write_nstream value to
determine how to do flush behind on writes. The default
value is 64K.
write_pref_io
The number of parallel read requests of size
read_pref_io to have outstanding at one time. The file
system uses the product of read_nstream multiplied by
read_pref_io to determine its read ahead size. The
default value for read_nstream is 1.
read_nstream
45VxFS performance: creating, mounting, and tuning file systems
Tuning I/O