tundefault Command

Purpose

Reset all tunable parameters to their default value.

Syntax

tundefault [ -r [-K] | -p ]

Description

The tundefault command starts all the tuning commands (ioo, vmo, schedo, no, nfso, and raso) with the -D flag. This resets all the AIX tunable parameters to their default value, except for parameters of type Bosboot and Reboot, and parameters of type Incremental set at values bigger than their default value, unless -r was specified. Error messages are displayed for any parameter change impossible to make.

Flags

Item	Description
-K	Defers the reset operation of tunable parameters to its default value until the next Live Update operation. When you specify the -r flag, the tundefault command resets all tunable parameters in the specified nextboot and nextliveupdate files to its default value. The -r flag clears the stanzas in the /etc/tunables/nextboot file, and if necessary, prompts for the bosboot operation and displays a warning message that a reboot operation is required to apply the changes. The -K flag adds the stanzas with default value of the tunable parameters in the /etc/tunables/nextliveupdate file in the nextliveupdate file. This updated nextliveupdate file is used for the next Live Update operation.
-p	Makes the changes permanent: resets all the tunable parameters to their default values and updates the /etc/tunables/nextboot file.
-r	Defers the reset to their default value to next reboot. This clears stanzas in the /etc/tunables/nextboot file, and if necessary, proposes bosboot and warns that a reboot is needed

Tunable Parameter Types

Item	Description
Dynamic	Can be changed at any time.
Static	Can never be changed
Reboot	Can only be changed during the reboot sequence
Bosboot	Can only be changed by running bosboot and rebooting the machine
Mount	Changes made are only effective for future filesystems or directory mountings
Incremental	Can only be incremented, except at boot time.
Connect	Changes are only effective for future socket connections.

Examples

To permanently reset all tunable parameters to their default values, enter the following command:
```
tundefault -p
```
All of the tuning commands are launched with the -Dp flags. This resets all the tunable parameters to their default value. This also updates the /etc/tunables/nextboot file. This command completely and permanently resets all tunable parameters to their default values.
To defer the setting of all tunable parameters until next reboot, enter the following command:
```
tundefault -r 
```
This command calls all tuning commands with the -Dr flags. This clears all of the stanzas in the /etc/tunables/nextboot file, and if necessary, proposes bosboot and displays a message warning that a reboot is necessary to make the changes effective.
To defer setting all tunable parameters until next reboot and next Live Update operation, enter the following command:
```
tundefault -r -K
```
This command calls all tuning commands with the -DrK flags. This command clears all of the stanzas in the /etc/tunables/nextboot file, if necessary, proposes a bosboot operation and displays a message warning that a reboot is necessary to make the changes effective. In addition, this command also adds stanzas with the default values in the /etc/tunables/nextliveupdate file if a non-default value was set for the tunable parameter for the next Live Update operation.

Files

Item	Description
/usr/sbin/tundefault	Contains the tundefault command.
/etc/tunables/	Contains all the tunable files.