I was hoping to install trueNAS on an external SSD and use the internal USB boot drive of the QNAP as a backup boot drive if the SSD failed.
This doesn’t work because TrueNAS refuses to install unless the USB is either erased or is made a member of the boot pool which would be a disaster since writes would be limited to the slower device.
So the choice is clear: Allow the installer to Erase the USB drive and just keep the SSD as the only boot device.
Is there any “clean” way to preserve that internal boot disk as a backup?
The answer I believe is no because truenas is going to discover the internal USB and not be happy at all (unpredictable results perhaps?)…
So even with a workaround (install on the SSD, erase the USB; then remove the SSD, and install on the USB) truenas would be very unhappy because it would still see that backup boot-pool.
So SSD only boot is the way to go and leave the USB erased.
Am I right?