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Commands Reference, Volume 5

tunrestore Command


Restores tunable parameter values from a file in /etc/tunables.


turestore [ -r ] -f Filename

tunrestore -R

tunrestore -R can only be called from inittab.


The tunrestore command restores all tunable parameters values stored in a file.

tunrestore -f Filename immediatly applies Filename. All tunables listed in Filename are set to the value defined in this file. Tunables not listed in Filename are kept unchanged. Tunables explicitly set to DEFAULT are set to their default value.

tunrestore -r -f Filename applies Filename for the next boot. This is achieved by checking the specified file for inconsistencies (the equivalent of running tuncheck on it) and copying it over to /etc/tunables/nextboot. If bosboot is necessary, the user will be offered to run it.

tunrestore -R is only used during reboot. All tunables that are not already set to the value defined in the nextboot file are modified. Tunables not listed in the nextboot file are forced to their default value. All actions, warnings and errors are logged into /etc/tunables/lastboot.log.

Additionally, a new tunable file called /etc/tunables/lastboot is automatically generated. That file has all the tunables listed with numerical values. The values representing default values are marked with the comment DEFAULT VALUE. Its info stanza includes the checksum of the /etc/tunables/lastboot.log file to make sure pairs of lastboot/lastboot.log files can be identified.


-f Filename Specifies the name of the tunable file to apply. This is a name relative to /etc/tunables.
-r Makes the specified file become the new nextboot file.
-R Restores /etc/tunables/nextboot during boot process.

Tunable Parameter Types

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.


  1. To restore all tunable values stored in /etc/tunables/mytunable, type:
    tunrestore -f mytunable
  2. To validate /etc/tunables/mytunable and make it the new nextboot file, type:
     tunrestore -r -f mytunable


/usr/sbin/tunrestore Contains the tunrestore command.
/etc/tunables Contains all the tunable files.
/etc/tunables/nextboot Contains the values to be applied during the next boot.
/etc/tunables/lastboot Contains the values of all tunables after the last boot.
/etc/tunables/lastboot.log Contains messages, warnings and errors emitted by tunrestore during the last boot.

Related Information

The schedo Command, vmo command, ioo command, no command, nfso command, tuncheck Command, tundefault Command, and tunsave Command.

Tunables File Format in AIX 5L Version 5.2 Files Reference.

Kernel Tuning in AIX 5L Version 5.2 Performance Tools Guide and Reference.

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