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Tunable files and control commands for the files:

/etc/tunables/nextboot        <--values to be applied to the next reboot. This file is automatically applied at boot time.
/etc/tunables/lastboot        <--automatically generated at boot time. It contains the parameters, with their values after the last boot.
/etc/tunables/lasboot.log     <--contains the logging of the creation of the lastboot file, that is, any parameter change made is logged

(If a parameter appears several times in a stanza, only its first occurence is used. Everything following a number sign (#) is considered a comment and ignored)

tuncheck -f <filename>        check the tunables in the file, if a problem is detected, a warning is issued
tunsave -f <filename>         saves the currnet state of tunables in a file
tunrestore -f <filename>      change all tunables to values stored in a specified file
tundefault                    resets all tunables to their default values

This fileset contains the commands for tuning: bos.perf.tune


Tunable commands:

    vmo        Manages Virtual Memory Manager tunable parameters
    ioo        Manages Input/Output tunable parameters
    schedo     Manages CPU scheduler tunable parameters
    no         Manages network tuning parameters
    nfso       Manages Network File System (NFS) tuning parameters

Flags for these commands:
    -p        makes changes that apply to both current and reboot values (updates  the /etc/tunables/nextboot file in addition)
    -r        forces the change to go into effect on the next reboot  (it turns on the updating of the /etc/tunables/nextboot file)
    -o        diplays or sets individual parameters
    -d        resets individual tunable to default value (-D will reset all tunables to default values)
    -a        displays all parameters
    -L        lists attributes of one or all tunables
    -h <attr>     will give detailed nifo about that attributum (vmo -h maxperm%)

root@aix1: /root # vmo -L
NAME                      CUR    DEF    BOOT   MIN    MAX    UNIT           TYPE
cpu_scale_memp            8      8      8      1      64                       B
data_stagger_interval     n/a    161    161    0      4K-1   4KB pages         D

D = Dynamic: can be freely changed
B = Bosboot: can only be changed using bosboot and reboot
S = Static: the parameter can never be changed
R = Reboot: the parameter can only be changed during boot

vmo -o maxperm%=80            <--sets to 80

vmo -p -o maxperm%=80 -o maxclient%=80      <-- sets maxperm% and maxclient% to 80
                             (-p: sets both current and reboot values (updates current value and /etc/tunables/nextboot)

vmo -r -o lgpg_size=0 -o lgpg_regions=0     <--sets only in nextboot file,so after reboot will be activated



  1. Very useful.



  2. dude, u have twice the /etc/tunables/* description :-) and thx 4 ur notes too. jose h.

  3. your blog is awesome...you are the real MVP