Under A/UX 3.1, the SyQuest disks can be mounted and unmounted. To unmount a disk, you push the eject button on the drive and then throw the drive icon in the trash. The optical drives should work as well. To unmount a disk, you throw the drive icon in the trash and then push the eject button on the drive.
Note: Magneto Optical drives have not been tested on A/UX 3.1 so we cannot say for sure how well they will work.