/sbin/vxtunefs

작은 파일 io에 대한 최적값을 찾고 싶어서..
 

Problem

How To Change I/O Size for File System

Solution

This would be useful when the need to align the I/O size between an application, stripe unit size and filesystem is recommended or when a specific disk device I/O size is recommended.

Here is one specific example of how to use vxtunefs

How to Review settings

Syntax: 

# vxtunefs /mountpoint

Example:

# vxtunefs /db03  

How to Change settings

Syntax:

# /usr/lib/fs/vxfs/vxtunefs -s -o parameter=value /mountpoint

where:

   -s = set 

   -o = options

Example:

# /usr/lib/fs/vxfs/vxtunefs -s -o read_pref_io=8192 /db03  

# /usr/lib/fs/vxfs/vxtunefs -s -o write_pref_io=8192 /db03  

This would change the read and write I/O size to 8k.  However, it will not be persistent across a reboot.  To make the setting persistent, you will have to make an entry in the /etc/vx/tunefstab file.

/etc/vx/tunefstab syntax   (for filesystem/volume db03)

Syntax:

# block_device tunefs_options  

Example:

# grep db03  /etc/vx/tunefstab

...

/dev/vx/dsk/datadg/db03  read_pref_io=128k,read_nstream=4

/dev/vx/dsk/datadg/db03  write_pref_io=128k,read_nstream=4

...

Useful vxtunefs details from the man page:

    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 

    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.

이렇게 사용한다고 아직 값을 찾진 못했지만 계속 테스트중

참고!!
http://sfdoccentral.symantec.com/sf/5.0/hpux/html/fs_admin/ag_ch_performance_fs27.html