@Patrick M. Hausen Thank you so much for creating this valuable guide. Finally I have upgraded my FreeNAS 9.3 to TrueNAS 12.0 and increased the disk capacity applying the procedure as you describe to remove the legacy encryption.
My experience varied with TrueNAS 12.0-U4.1 slightly which even simplified the process.
0. run Disklist (see below) to capture all the necessary ids.
1. Use GUI to take one disk offline from the pool.
2. Command line
Code:
zpool replace <poolname> gtpid/<id>.eli gtpid/<id>
. Wait for resilvering to complete.
Repeat for all disks.
Export/Disconnect on the GUI (not to destroy data (off by default))
Reboot and Import.
Entries were removed from the freenas-v1.db by the process automatically.
One tool I found valuable is
https://github.com/nephri/FreeNas-DiskList with the discussion around the tool is on
ServeTheHome forum.
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OS Version: TrueNAS-12.0-U4.1
Model: ProLiant MicroServer