What is the issue you are having? Do you have a USB attached boot pool with mirroring? If you trying to use multiple MYBook drives attached by USB, that will still be considered ‘unsupported’. You can look into shucking the drives from the cases and attaching them directly using SATA.
NAS-139947 is showing the problem with USB attached boot-pool in mirror as fixed in 25.10.3 and the 26.0.0 Beta1. That specific setup was causing issues with SATA or SAS pool creation at the time.
I had a different make/model USB drive attached and it was causing the problem. I removed it and its working. I didn’t realize I couldn’t have multiple attached. I guess that’s the “bug” or whatever?
I don’t know if some code was changed in the 25.10 series but that is when we started to see more issues with ‘duplicate serial numbers’ If the Bug report showed USB, Thunderbolt, or a few known, troublesome SAS shelfs, they were closed as ‘unsupported’.
You should be okay if you stick with SATA or SAS.
