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Last Modified 2021-07-30 09:07 EDT

System > Advanced contains more advanced options for configuring system settings.

These options have reasonable defaults in place. Make sure you are comfortable with ZFS, FreeBSD, and system configuration backup and restoration before making any changes.

System Advanced


Show Text Console without Password PromptUnset to add a login prompt to the system before the console menu is shown.
Enable Serial ConsoleDo not set this if the Serial Port is disabled. Serial Port and Serial Speed options are visible when this is set.
Serial PortWhen Enable Serial Console is set, the available serial port hex addresses are 0x2F8 or 0x3f8.
Serial SpeedsWhen Enable Serial Console is set, the available serial speeds that can be used by the serial port are 9600 bps, 19200 bps, 38400 bps, 57600 bps, or 115200bps.
MOTD BannerThe message to show when a user logs in with SSH.


Swap Size in GiB (CORE only)By default, all data disks are created with the amount of swap specified. Changing the value does not affect the amount of swap on existing disks, only disks added after the change. Does not affect log or cache devices as they are created without swap. Setting to 0 disables swap creation completely. STRONGLY DISCOURAGED
LOG (Write Cache) Overprovision Size in GiBOverprovisioning a ZFS Log SSD can increase its performance and lifespan by distributing writes and erases across more drive flash blocks. Defining a number of GiB here overprovisions ZFS Log disks during pool creation or extension. Examples: 50 GiB, 10g, 5GB


Show Console MessagesDisplay console messages in real time at the bottom of the browser.
Show Advanced Fields by DefaultSet to always show advanced fields, when available.


Show Console MessagesDisplay console messages in real time at the bottom of the browser.
Show Advanced Fields by DefaultSet to always show advanced fields, when available.

Self-Encrypting Drive

ATA Security UserUser passed to camcontrol security -u to unlock SEDs
SED PasswordGlobal password to unlock SEDs.


Use FQDN for LoggingSet to include the Fully-Qualified Domain Name (FQDN) in logs to precisely identify systems with similar hostnames.
Syslog LevelWhen Syslog Server is defined, only logs matching this level are sent.
Syslog ServerRemote syslog server DNS hostname or IP address. Nonstandard port numbers can be used by adding a colon and the port number to the hostname, like mysyslogserver:1928. Log entries are written to local logs and sent to the remote syslog server.
Syslog TransportTransport Protocol for the remote system log server connection. Choosing Transport Layer Security (TLS) also requires selecting a preconfigured system Certificate.

There is also an option to SAVE DEBUG. This generates text files that contain diagnostic information. After the debug data is collected, the system prompts for a location to save the compressed .tar file.


TrueNAS provides an autotune script that optimizes the system depending on the installed hardware.

To see which checks are performed, the autotune script is located in /usr/local/bin/autotune.

For example, if a pool exists on a system with limited RAM, the autotune script automatically adjusts some ZFS sysctl values in an attempt to minimize memory starvation issues. Autotuning can introduce system performance issues and must only be used as a temporary measure on a system until the underlying hardware issue is addressed. Autotune always slows a RAM-starved system, as it caps the ARC.

Using the autotuning script is not recommended for TrueNAS Enterprise customers as this can override any specific tunings made by iXsystems Support.

Enabling autotuning runs the autotuner script at boot. To run the script immediately, reboot the system.

Any tuned settings appear in System > Tunables.

Deleting tunables created by the autotune only affects the current session. Autotune-set tunables are recreated every time the system boots. This means any setting controlled by the autotuner does not allow for further manual tuning.

To permanently change a value set by autotune, change the description of the tunable. For example, changing the description to manual override prevents autotune from reverting that tunable back to the autotune default value.

When attempting to increase the performance of the TrueNAS system, and particularly when the current hardware is limiting performance, try enabling autotune.