TrueNAS SimplifySwap

Introduction

By default, a TrueNAS Scale system uses mirrored encrypted swap space on each disk of the volume selected in the configuration. This has been the default since at least 24.04 Dragonfish. On older systems with low memory, the load of doing constant encryption for swap can make the system unstable and nearly unusable. Furthermore, allowing striping (RAID0) instead of mirroring (RAID1) for swap should also significantly help swap performance, at the risk of system instability in the case of disk failure.

This implementation is a conceptually simple script that checks if the default swap configuration is active, and, if so, live-replaces it without downtime to remove encryption and instead use the kernel's default RAID0 swap capability. This would need to be done on each startup since the startup scripts in TrueNAS Scale rebuild the swap configuration during boot if it isn't in the expected configuration. So the solution is to simply add a startup script in TrueNAS Scale's UI to call this script on startup to correct it later in the boot process.

Setup

The setup for this is quite simple:

1. Login to your TrueNAS Scale Web UI as an administrator

2. Click on the System Settings navigation link on the left

3. Click on the Advanced option from the submenu

4. In the section titled Init/Shutdown Scripts, click the Add button

5. The Add Init/Shutdown Scripts dialog pops up:

   Entry Fields	Description
   Description	simplify swap (unencrypt + raid0 for faster swapping)
   Type	Command
   Command	/path/to/your/TrueNAS_SimplifySwap/simplify-swap.sh
   When	Post Init
   Enabled	Check to enable system suspend; disable if issues arise.
   Timeout	90 You can adjust this if necessary

   • Command:

     • The simplify-swap.sh script does not support any command line options, but it can be used interactively via ssh to provide some output describing what is happening and indicating if something is going wrong in the process.

     • The included activate-simple-swap.sh script is much simpler; it just activates any existing swap partitions, identified by the standard GPT 'partition type' ID. Depending on your system configuration, this script may be useful. Similarly, it does not need any command line options, and can be used interactively via ssh to provide some output describing what is happening and indicating if something is going wrong in the process.

     • Typically, output from CLI commands or scripts run this way are not logged, and therefore the output is lost. You can retain the information and messages by changing the command field to something like the following:

       /path/to/your/TrueNAS_SimplifySwap/simplify-swap.sh >> /root/simplify-swap.stdout 2>> /root/simplify-swap.stderr

       This would save output into files /root/simplify-swap.stdout and /root/simplify-swap.stderr to hopefully help with debugging.

       These output files will grow on each system bootup and will never be rotated or removed without manual intervention, so when you finish debugging, make sure to restore the command field and delete the output files.

       Alternatively, you can check out my shLogger project, which does much of the hard work of managing a log file: https://github.com/gissf1/shlogger/ and it would work like this:

       /path/to/your/shlogger -o /path/to/your/simplify-swap.log -s 10485760 /path/to/your/TrueNAS_SimplifySwap/simplify-swap.sh

       You can use these logging methods to enable output logging for either script (or other commands) by substituting the appropriate script name in the command line.

   • Enabled:

     • Check this to enable the script at startup
     • Also an easy way to disable if issues arise

6. Click the Save button

Issues / Technical Support

You can report issues or request support using Github issues at https://github.com/gissf1/TrueNAS_SimplifySwap/issues

Development Contribution

If this was extremely useful to you, and you're feeling generous, please feel free to donate on my github page at https://github.com/sponsors/gissf1

Also consider contacting me with business opportunities, especially if you would like to sponsor changes to this project, or wish to offer other collaboration or contracting opportunities.

Licensing

All files in this project are covered under the license described in the LICENSE file. If they do not have a file header, this license applies by default as if it had the appropriate header.