root_device cwtxdysz
root_device specifies the device to be used for the root pool. The root_device keyword determines where the operating system is installed. This keyword is used the same in both ZFS and a UFS file system with some limitations. For the ZFS root pool, the root device is limited to a single system. This keyword is not useful for mirrored pools.
Identifies the root disk where the operating system is installed.