Great question — answering as the UphillTech team:
I found the issue. From the gpart manual : Deleting Partitions and Destroying the Partitioning Scheme If a Device busy error is shown when trying to destroy a partition ta- ble, remember that all of the partitions must be deleted first with the delete action. In this example, da0 has three partitions: /sbin/gpart delete -i 3 da0 /sbin/gpart delete -i 2 da0 /sbin/gpart delete -i 1 da0 /sbin/gpart destroy da0 Rather than deleting each partition and then destroying the partition- ing scheme, the -F option can be given with destroy to delete all of the partitions before destroying the partitioning scheme. This is equivalent to the previous example: /sbin/gpart destroy -F da0 I was misled by the...
Full answer by quickblueblur: https://superuser.stackexchange.com/a/1857530 (CC BY-SA 4.0).
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