Configuring System Tunables

A how-to for adding system Tunables in TrueNAS.

  2 minute read

Introduction

TrueNAS allows you to add system tunables from the web interface. Tunables are used to manage TrueNAS sysctls, loaders, and rc.conf options.

loader tunables are used to specify parameters to pass to the kernel or load additional modules at boot time. rc.conf tunables are for enabling system services and daemons and only take effect after a reboot. sysctl tunables are used to configure kernel parameters while the system is running and generally take effect immediately.

Configuring System Tunables

To configure a tunable, go to System > Tunables and click ADD. First, select the Type of tunable to add or modify. Enter the name of the loader, sysctl, or rc.conf variable to configure. Next, enter the value to use for the loader, sysctl, or rc.conf. An optional description can be given. If you wish to create the system tunable but not immediately enable it, unset the Enable checkbox. Configured tunables remain in effect until deleted or Enabled is unset.

Restarting the TrueNAS system after making sysctl changes is recommended. Some sysctls only take effect at system startup, and restarting the system guarantees that the setting values correspond with what is being used by the running system.

Be careful when adding or editing the default tunables. Changing the default tunables can make the system unusable.


Last modified July 21, 2020: add some more info. (7631a988)