Installed from v1.6.6 with most settings default as below.
It started mirroring the internal SD card to the external one although with backupdrive commented out, it shouldn't have.
# external SD card device to backup and mirror the internal SD card to
# backupdrive=/dev/sda
storageconfig=openhab-dir
storagedir=/storage
storagetapes=15
storagecapacity=1024
Installed from v1.6.6 with most settings default as below. It started mirroring the internal SD card to the external one although with backupdrive commented out, it shouldn't have.
first-boot.log