TLDR: I tried to replace my mirrored boot drives and got an error message “Unable to locate VDEV”, so I installed TrueNAS to the new drives and restored the configuration instead. I’d like to know what caused the error.
I had Scale 24.04 installed to a mirrored pair of 240GB NVME drives. I considered this overkill, so decided to replace the drives with a pair of 250GB SATA SSDs instead. I tried to do this from the Boot Pool Status screen, but each time I tried to use the Replace option from the menu button for either drive, the process failed.
The SSDs were recognised and formatted, but the process failed immediately afterward, reporting that error message (sorry, don’t have it in full) in reference to the NVME drives, specifically the NVME that I was trying to replace. This happened with both NVME drives and both SSDs, in any combination.
I couldn’t find any information on why this was happening, or how to fix it, so I just installed TrueNAS onto the two SSDs instead, then restored the configuration. The system is running as normal and I’ve repurposed the NVMEs into a new pool with no issues.
So what went wrong? If I’d had a failed boot drive, I wouldn’t have been able to replace it, nor would I have been able to detach it from the mirror and then attach a new drive as there was (and is) no option other than Replace in the menu for either drive.